release/src/router/libpcap/pcap-sita.html

   1 <HTML><HEAD>
   2 <STYLE type="text/css">
   3 <!--
   4 A { text-decoration:none }
   5 -->
   6 </STYLE>
   7 </HEAD>
   8 <BODY>
   9
  10 <TABLE WIDTH=100%><TR>
  11         <TD ALIGN=LEFT VALIGN=TOP>
  12                 <FONT SIZE=+0 FACE="COURIER"><B>A "Distributed Pcap" for<BR>Remote Monitoring LANs & WANs</B><BR>
  13                                                                                 (Design Notes for the SITA ACN device)</FONT>
  14         </TD>
  15         <TD ALIGN=RIGHT VALIGN=TOP>
  16                 Fulko Hew<BR>SITA INC Canada, Inc.<BR>Revised: October 2, 2007
  17         </TD>
  18 </TR></TABLE>
  19
  20
  21 <H3>SUMMARY</H3>
  22 <UL>
  23         <STRONG>Note:</STRONG> This document is part of the libpcap Git and was derived from 'pcap.3' (circa Aug/07).
  24         <P>
  25         The ACN provides a customized/distributed version of this library that alows SMPs to
  26         interact with the various IOPs within the site providing a standard mechanism
  27         to capture LAN and WAN message traffic.
  28         <P>
  29         <CENTER>
  30                 <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3 WIDTH=75%>
  31                         <TR>
  32                                 <TH VALIGN=TOP>SMP</TH>
  33                                 <TD VALIGN=TOP>The Supervisory Management Processor where Wireshark (or equivalent)
  34                                                                 runs in conjuction with a libpcap front-end.</TD>
  35                         </TR>
  36                         <TR>
  37                                 <TH VALIGN=TOP>IOP</TH>
  38                                 <TD VALIGN=TOP>I/O Processors where the monitored ports exist in conjunction
  39                                                                 with a custom device driver/libpcap back-end.</TD>
  40                         </TR>
  41                 </TABLE>
  42         </CENTER>
  43         <P>
  44         Each IOP will be capable of supporting multiple connections from an SMP
  45         enabling monitoring of more than one interface at a time, each through
  46         its own seperate connection.  The IOP is responsible to ensure and report
  47         an error if any attempt is made to monitor the same interface more than once.
  48         <P>
  49         There are three applications that will be supported by the ACN version of libpcap.
  50         They each use a slightly different mode for looping/capturing and termination
  51         as summarized in the following table:
  52         <P>
  53         <CENTER>
  54         <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
  55         <TR><TH>Application</TH>        <TH>Capture</TH>        <TH>Termination</TH></TR>
  56         <TR><TH VALIGN=TOP NOWRAP>wireshark</TH>
  57                         <TD VALIGN=TOP>pcap_dispatch(all packets in one buffer of capture only)</TD>
  58                         <TD VALIGN=TOP>pcap_breakloop()</TD>
  59                 </TR>
  60         <TR><TH VALIGN=TOP NOWRAP>tshark</TH>
  61                         <TD VALIGN=TOP>pcap_dispatch(one buffer of capture only)</TD>
  62                         <TD VALIGN=TOP>Since a CTRL-C was used to terminate the application, pcap_breakloop() is never called.</TD>
  63                 </TR>
  64         <TR><TH VALIGN=TOP NOWRAP>tcpdump</TH>
  65                         <TD VALIGN=TOP>pcap_loop(all packets in the next buffer, and loop forever)</TD>
  66                         <TD VALIGN=TOP>pcap_breakloop()</TD>
  67                 </TR>
  68         </TABLE>
  69         </CENTER>
  70         <P>
  71         <B>Note: </B>In all cases, the termination of capturing is always (apparently) followed by
  72         pcap_close().  Pcap_breakloop() is only used to stop/suspend looping/processing,
  73         and upon close interpretation of the function definitions, it is possible to resume
  74         capturing following a pcap_breakloop() without any re-initialization.
  75         <P>
  76         <H4>ACN Limitations</H4>
  77         <OL>
  78                 <LI>Monitoring of backup IOPs is not currently supported.
  79                 <LI>Ethernet interfaces cannot be monitored in promiscuous mode.
  80         </OL>
  81
  82 </UL>
  83
  84 <H3>ROUTINES</H3>
  85 <UL>
  86                 The following list of functions is the sub-set of Pcap functions that have been
  87                 altered/enhanced to support the ACN remote monitoring facility.  The remainder of the Pcap
  88                 functions continue to perform their duties un-altered.  Libpcap only supports this
  89                 mode of operation if it has been configured/compiled for SITA/ACN support.
  90                 <P>
  91                 <UL><FONT FACE=COURIER>
  92                         pcap_findalldevs<BR>
  93                         pcap_freealldevs<BR>
  94                         pcap_open_live<BR>
  95                         pcap_close<BR>
  96                         pcap_setfilter<BR>
  97                         pcap_dispatch<BR>
  98                         pcap_loop<BR>
  99                         pcap_next<BR>
 100                         pcap_next_ex<BR>
 101                         pcap_stats<BR>
 102                 </FONT></UL>
 103
 104         These subroutines have been modified for the ACN specific distributed and remote monitoring
 105         ability perform the following basic functions.  More detail is provided in the
 106         "SMP/IOP Inter-Process Communication Protocol" section.
 107         <P>
 108 <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 109         <TR>
 110                 <TD VALIGN=TOP ROWSPAN=2><B>pcap_open_live()</B></TD>
 111                 <TD VALIGN=TOP>Used to obtain a packet capture descriptor to look at packets on the network.</TD>
 112         </TR>
 113         <TR><TD><TABLE BORDER=0 CELLSPACING=0 CELLPADDING=3 WIDTH=100%>
 114                 <TR><TH VALIGN=TOP NOWRAP>SMP -> IOP</TH>
 115                         <TD>
 116                         The SMP will open a connection to the selected IOP on its 'sniffer' port
 117                         to ensure it is available.  It sends a null terminated string identifying
 118                         the interface to be monitored.
 119                         </TD>
 120                 </TR>
 121                 <TR><TH VALIGN=TOP NOWRAP>IOP -> SMP</TH>
 122                         <TD>
 123                         After any required processing is complete, the IOP will return a
 124                         null terminated string containing an error message if one occured.
 125                         If no error occured, a empty string is still returned.
 126                         Errors are:
 127                         <UL>
 128                         <LI>"Interface (xxx) does not exist."
 129                         <LI>"Interface (xxx) not configured."
 130                         <LI>"Interface (xxx) already being monitored."
 131                         </UL>
 132                         </TD>
 133                 </TR>
 134         </TABLE></TD></TR>
 135
 136         <TR>
 137                 <TD VALIGN=TOP ROWSPAN=2><B>pcap_findalldevs()</B></TD>
 138                 <TD VALIGN=TOP>It constructs a list of network devices that can be opened with pcap_open_live().</TD>
 139         </TR>
 140         <TR><TD><TABLE BORDER=0 CELLSPACING=0 CELLPADDING=3 WIDTH=100%>
 141                 <TR><TH VALIGN=TOP NOWRAP>SMP</TH>
 142                         <TD>
 143                         It obtains a list of IOPs currently available (via /etc/hosts).
 144                         </TD>
 145                 </TR>
 146                 <TR><TH VALIGN=TOP NOWRAP>SMP -> IOP</TH>
 147                         <TD>
 148                         The SMP will sequentially open a connection to each IOP on its 'sniffer' port to ensure
 149                         the IOP is available.
 150                         It sends a null terminated empty interface ID followed by the query request command.
 151                         </TD>
 152                 </TR>
 153                 <TR><TH VALIGN=TOP NOWRAP>IOP -> SMP</TH>
 154                         <TD>The IOP returns an error response and its list of devices.
 155                         </TD>
 156                 </TR>
 157                 <TR><TH VALIGN=TOP NOWRAP>SMP -> IOP</TH>
 158                         <TD>
 159                         The SMP closes the TCP connection with each IOP.
 160                         </TD>
 161                 </TR>
 162                 <TR><TH VALIGN=TOP NOWRAP>SMP</TH>
 163                         <TD>
 164                         The SMP adds the received information to its internal structure.
 165                         </TD>
 166                 </TR>
 167         </TABLE></TD></TR>
 168
 169         <TR>
 170                 <TD VALIGN=TOP ROWSPAN=2><B>pcap_freealldevs()</B></TD>
 171                 <TD VALIGN=TOP>Used to free a list allocated by pcap_findalldevs().</TD>
 172         </TR>
 173         <TR><TD><TABLE BORDER=0 CELLSPACING=0 CELLPADDING=3 WIDTH=100%>
 174                 <TR><TH VALIGN=TOP NOWRAP>SMP</TH>
 175                         <TD>
 176                         The SMP frees the structure it built as a result of the previous
 177                         invocation of pcap_findalldevs().
 178                         </TD>
 179                 </TR>
 180         </TABLE></TD></TR>
 181
 182         <TR>
 183                 <TD VALIGN=TOP ROWSPAN=2><B>pcap_dispatch()</B></TD>
 184                 <TD VALIGN=TOP>Used to collect and process packets.</TD>
 185         </TR>
 186         <TR><TD><TABLE BORDER=0 CELLSPACING=0 CELLPADDING=3 WIDTH=100%>
 187                 <TR><TH VALIGN=TOP NOWRAP>SMP -> IOP</TH>
 188                         <TD>
 189                         On the first invocation of pcap_dispatch(), pcap_loop(), or pcap_next(), or pcap_next_ex() following a pcap_open_live(),
 190                         the SMP will pass down the monitor start command and various parameters the IOP should use.
 191                         </TD>
 192                 </TR>
 193                 <TR><TH VALIGN=TOP NOWRAP>IOP -> SMP</TH>
 194                         <TD>
 195                         The IOP now sends a stream of captured data.
 196                         </TD>
 197                 </TR>
 198                 <TR><TH VALIGN=TOP NOWRAP>SMP</TH>
 199                         <TD>
 200                         The SMP will read the reverse channel of the connection between the SMP and the
 201                         IOP that provides the captured data (via 'p->read_op' which is 'pcap_read_linux()'
 202                         until the select() call returns a 'no more data' indication.
 203                         It will the process (at most) the next 'cnt' packets and invoke the specified
 204                         callback function for each packet processed.
 205                         </TD>
 206                 </TR>
 207                 <TR><TH VALIGN=TOP NOWRAP>IOP</TH>
 208                         <TD>
 209                         The IOP continues to listen for additional commands as well as capturing and forwarding data to the SMP.
 210                         </TD>
 211                 </TR>
 212         </TABLE></TD></TR>
 213
 214         <TR>
 215                 <TD VALIGN=TOP ROWSPAN=2><B>pcap_loop()</B></TD>
 216                 <TD VALIGN=TOP>
 217                                 Is similar to pcap_dispatch() except it keeps reading packets until
 218                                 the requested number of packets are processed or an error occurs.
 219                 </TD>
 220         </TR>
 221         <TR><TD><TABLE BORDER=0 CELLSPACING=0 CELLPADDING=3 WIDTH=100%>
 222                 <TR><TH VALIGN=TOP NOWRAP>SMP -> IOP</TH>
 223                         <TD>
 224                         On the first invocation of pcap_dispatch(), pcap_loop(), or pcap_next(), or pcap_next_ex() following a pcap_open_live(),
 225                         the SMP will pass down the monitor start command and various parameters the IOP should use.
 226                         </TD>
 227                 </TR>
 228                 <TR><TH VALIGN=TOP NOWRAP>IOP -> SMP</TH>
 229                         <TD>
 230                         The IOP now sends a stream of captured data.
 231                         </TD>
 232                 </TR>
 233                 <TR><TH VALIGN=TOP NOWRAP>SMP</TH>
 234                         <TD>
 235                         The SMP continuously reads the next packet from the reverse channel of the connection
 236                         between the SMP and the IOP that provides the captured data (via 'p->read_op'
 237                         which is 'pcap_read_linux()' until 'cnt' packets have been received.
 238                         The specified callback function will be invoked for each packet received.
 239                         </TD>
 240                 </TR>
 241                 <TR><TH VALIGN=TOP NOWRAP>IOP</TH>
 242                         <TD>
 243                         The IOP continues to listen for additional commands as well as capturing and forwarding data to the SMP.
 244                         </TD>
 245                 </TR>
 246         </TABLE></TD></TR>
 247
 248         <TR>
 249                 <TD VALIGN=TOP ROWSPAN=2><B>pcap_next()</B></TD>
 250                 <TD VALIGN=TOP>
 251                         It reads the next packet (by calling pcap_dispatch() with a count of 1)
 252                         and returns a pointer to the data in that packet.
 253                 </TD>
 254         </TR>
 255         <TR><TD><TABLE BORDER=0 CELLSPACING=0 CELLPADDING=3 WIDTH=100%>
 256                 <TR><TH VALIGN=TOP NOWRAP>SMP -> IOP</TH>
 257                         <TD>
 258                         On the first invocation of pcap_dispatch(), pcap_loop(), or pcap_next(), or pcap_next_ex() following a pcap_open_live(),
 259                         the SMP will pass down the monitor start command and various parameters the IOP should use.
 260                         </TD>
 261                 </TR>
 262                 <TR><TH VALIGN=TOP NOWRAP>IOP -> SMP</TH>
 263                         <TD>
 264                         The IOP now sends a stream of captured data.
 265                         </TD>
 266                 </TR>
 267                 <TR><TH VALIGN=TOP NOWRAP>SMP</TH>
 268                         <TD>
 269                         The SMP reads only the next packet from the reverse channel of the connection
 270                         between the SMP and the IOP that provides the captured data (via calling pcap_dispatch()
 271                         with a count of 1) and returns a pointer to that data by invoking an internal callback.
 272                         </TD>
 273                 </TR>
 274                 <TR><TH VALIGN=TOP NOWRAP>IOP</TH>
 275                         <TD>
 276                         The IOP continues to listen for additional commands as well as capturing and forwarding data to the SMP.
 277                         </TD>
 278                 </TR>
 279         </TABLE></TD></TR>
 280
 281         <TR>
 282                 <TD VALIGN=TOP ROWSPAN=2><B>pcap_next_ex()</B></TD>
 283                 <TD VALIGN=TOP>Reads the next packet and returns a success/failure indication.</TD>
 284         </TR>
 285         <TR><TD><TABLE BORDER=0 CELLSPACING=0 CELLPADDING=3 WIDTH=100%>
 286                 <TR><TH VALIGN=TOP NOWRAP>SMP -> IOP</TH>
 287                         <TD>
 288                         On the first invocation of pcap_dispatch(), pcap_loop(), or pcap_next(), or pcap_next_ex() following a pcap_open_live(),
 289                         the SMP will pass down the monitor start command and various parameters the IOP should use.
 290                         </TD>
 291                 </TR>
 292                 <TR><TH VALIGN=TOP NOWRAP>IOP -> SMP</TH>
 293                         <TD>
 294                         The IOP now sends a stream of captured data.
 295                         </TD>
 296                 </TR>
 297                 <TR><TH VALIGN=TOP NOWRAP>SMP</TH>
 298                         <TD>
 299                         The SMP reads only the next packet from the reverse channel of the connection
 300                         between the SMP and the IOP that provides the captured data (via calling pcap_dispatch()
 301                         with a count of 1) and returns seperate pointers to both the
 302                         packet header and packet data by invoking an internal callback.
 303                         </TD>
 304                 </TR>
 305                 <TR><TH VALIGN=TOP NOWRAP>IOP</TH>
 306                         <TD>
 307                         The IOP continues to listen for additional commands as well as capturing and forwarding data to the SMP.
 308                         </TD>
 309                 </TR>
 310         </TABLE></TD></TR>
 311
 312         <TR>
 313                 <TD VALIGN=TOP ROWSPAN=2><B>pcap_setfilter()</B></TD>
 314         <TD VALIGN=TOP>Used to specify a filter program.</TD>
 315         </TR>
 316         <TR><TD><TABLE BORDER=0 CELLSPACING=0 CELLPADDING=3 WIDTH=100%>
 317                 <TR><TH VALIGN=TOP NOWRAP>SMP -> IOP</TH>
 318                         <TD>
 319                         The SMP sends a 'set filter' command followed by the BPF commands.
 320                         </TD>
 321                 </TR>
 322                 <TR><TH VALIGN=TOP NOWRAP>IOP -> SMP</TH>
 323                         <TD>
 324                         The IOP returns a null terminated error string if it failed to accept the filter.
 325                         If no error occured, then a NULL terminated empty string is returned instead.
 326                         Errors are:
 327                         <UL>
 328                         <LI>"Invalid BPF."
 329                         <LI>"Insufficient resources for BPF."
 330                         </UL>
 331                         </TD>
 332                 </TR>
 333         </TABLE></TD></TR>
 334
 335         <TR>
 336                 <TD VALIGN=TOP ROWSPAN=2><B>pcap_stats()</B></TD>
 337         <TD VALIGN=TOP>Fills in a pcap_stat struct with packet statistics.</TD>
 338         </TR>
 339         <TR><TD><TABLE BORDER=0 CELLSPACING=0 CELLPADDING=3 WIDTH=100%>
 340                 <TR><TH VALIGN=TOP NOWRAP>SMP -> IOP</TH>
 341                         <TD>
 342                         The SMP sends a message to the IOP requesting its statistics.
 343                         </TD>
 344                 </TR>
 345                 <TR><TH VALIGN=TOP NOWRAP>IOP -> SMP</TH>
 346                         <TD>
 347                         The IOP returns the statistics.
 348                         </TD>
 349                 </TR>
 350                 <TR><TH VALIGN=TOP NOWRAP>SMP</TH>
 351                         <TD>
 352                         The SMP fills in the structure provided with the information retrieved from the IOP.
 353                         </TD>
 354                 </TR>
 355         </TABLE></TD></TR>
 356
 357         <TR>
 358                 <TD VALIGN=TOP ROWSPAN=2><B>pcap_close()</B></TD>
 359         <TD VALIGN=TOP>Closes the file and deallocates resources.</TD>
 360         </TR>
 361         <TR><TD><TABLE BORDER=0 CELLSPACING=0 CELLPADDING=3 WIDTH=100%>
 362                 <TR><TH VALIGN=TOP NOWRAP>SMP -> IOP</TH>
 363                         <TD>
 364                         The SMP closes the file descriptor, and if the descriptor is that of
 365                         the comminucation session with an IOP, it too is terminated.
 366                         </TD>
 367                 </TR>
 368                 <TR><TH VALIGN=TOP NOWRAP>IOP</TH>
 369                         <TD>
 370                         If the IOP detects that its communication session with an SMP
 371                         has closed, it will terminate any monitoring in progress,
 372                         release any resources and close its end of the session.
 373                         It will not maintain persistance of any information or prior mode of operation.
 374                         </TD>
 375                 </TR>
 376         </TABLE></TD></TR>
 377 </TABLE>
 378 </UL>
 379
 380 <P>
 381 <H3>SMP/IOP Inter-Process Communication Protocol</H3>
 382
 383 <UL>
 384         <LI><P>Communications between an SMP and an IOP consists of a TCP session
 385                         between an ephemeral port on the SMP and the well known port of 49152
 386                         (which is the first available port in the 'dynamic and/or private port'
 387                         range) on an IOP.
 388         <LI><P>Following a TCP open operation the IOP receives a null terminated
 389                         'interface ID' string to determine the type of operation that follows:
 390         <LI><P>Every command received by an IOP implies a 'stop trace/stop forwarding' operation must
 391                         occur before executing the received command.
 392         <LI><P>A session is closed when the SMP closes the TCP session with the IOP.
 393                         Obviously monitoring and forwarding is also stopped at that time.
 394
 395         <B>Note: </B>All multi-octet entities are sent in network neutral order.
 396         <P>
 397
 398         <TABLE BORDER=0 CELLSPACING=0 CELLPADDING=5>
 399                 <TR><TH COLSPAN=3><HR WIDTH=100%></TH></TR>
 400                 <TR>
 401                         <TD VALIGN=TOP ROWSPAN=6>pcap_findalldevs()</TD>
 402                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>SMP -> IOP</TD>
 403                         <TD VALIGN=TOP>Open socket (to each IOP), and sends:
 404                                 <P>
 405                                 <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 406                                         <TR>
 407                                         <TH VALIGN=TOP ALIGN=CENTER>Name/<BR>Purpose</TH>
 408                                         <TH VALIGN=TOP ALIGN=CENTER NOWRAP>Size<BR>(in bytes)</TH>
 409                                         <TH VALIGN=TOP ALIGN=CENTER>Description</TH>
 410                                         </TR>
 411                                         <TR>
 412                                                 <TD VALIGN=TOP>Interface ID</TD>
 413                                                 <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 414                                                 <TD VALIGN=TOP>A NULL to indicate an an empty 'interface ID'.</TD>
 415                                         </TR>
 416                                 </TABLE>
 417                         </TD>
 418                 </TR>
 419                 <TR>
 420                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>IOP -> SMP</TD>
 421                         <TD VALIGN=TOP>Send its (possibly empty) NULL terminated error response string.</TD>
 422                 </TR>
 423                 <TR>
 424                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>SMP -> IOP</TD>
 425                         <TD VALIGN=TOP>Sends the 'interface query request':
 426                                 <P>
 427                                 <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 428                                         <TR>
 429                                         <TH VALIGN=TOP ALIGN=CENTER>Name/<BR>Purpose</TH>
 430                                         <TH VALIGN=TOP ALIGN=CENTER NOWRAP>Size<BR>(in bytes)</TH>
 431                                         <TH VALIGN=TOP ALIGN=CENTER>Description</TH>
 432                                         </TR>
 433                                         <TR>
 434                                                 <TD VALIGN=TOP>Interface ID</TD>
 435                                                 <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 436                                                 <TD VALIGN=TOP>A 'Q' (indicating 'interface query request').</TD>
 437                                         </TR>
 438                                 </TABLE>
 439                         </TD>
 440                 </TR>
 441                 <TR>
 442                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>IOP -> SMP</TD>
 443                         <TD VALIGN=TOP>The IOP returns a list of sequences of information as
 444                                 defined by the return parameter of this function call (as shown in the following table).
 445                                 Elements are specified by providing an unsigned byte preceeding the actual data that contains length information.
 446                                 <P>
 447                                 <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 448                                 <TR>
 449                                         <TH VALIGN=TOP ALIGN=CENTER>Notes:</TH>
 450                                         <TH VALIGN=TOP ALIGN=CENTER>Name/<BR>Purpose</TH>
 451                                         <TH VALIGN=TOP ALIGN=CENTER NOWRAP>Size<BR>(in bytes)</TH>
 452                                         <TH VALIGN=TOP ALIGN=CENTER>Description</TH>
 453                                 </TR>
 454                                 <TR>
 455                                         <TD ROWSPAN=7>&nbsp;</TD>
 456                                         <TD VALIGN=TOP ALIGN=RIGHT>length</TD>
 457                                         <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 458                                         <TD VALIGN=TOP>The number of octets in the name field that follows.</TD>
 459                                 </TR>
 460                                 <TR><TD VALIGN=TOP ALIGN=LEFT>Name</TD>
 461                                         <TD VALIGN=TOP ALIGN=CENTER>1-255</TD>
 462                                         <TD VALIGN=TOP>The name of the interface. The format of the name is an alphabetic string (indicating
 463                                                                         the type of interface) followed by an optional numeric string (indicating the interface's
 464                                                                         sequence number).
 465                                                                         Sequence numbers (if needed) will begin at zero and progress monotonically upwards.
 466                                                                         (i.e. 'eth0', 'lo', 'wan0', etc.)
 467                                                                         <P>
 468                                                                         For an IOP, the alphabetic string will be one of: 'eth', 'wan', and 'lo'
 469                                                                         for Ethernet, WAN ports and the IP loopback device respectively.
 470                                                                         An IOP currently supports: 'eth0', 'eth1', 'lo', 'wan0' ... 'wan7'.
 471                                                                         <P>
 472                                                 <B>Note:</B> IOPs and ACNs will not currently support the concept of 'any' interface.</TD>
 473                                 </TR>
 474                                 <TR><TD VALIGN=TOP ALIGN=RIGHT>length</TD>
 475                                         <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 476                                         <TD VALIGN=TOP>The number of octets in the interface description field that follows.</TD>
 477                                 </TR>
 478                                 <TR><TD VALIGN=TOP ALIGN=LEFT>Interface Description</TD>
 479                                         <TD VALIGN=TOP ALIGN=CENTER>0-255</TD>
 480                                         <TD VALIGN=TOP>A description of the interface or it may be an empty string. (i.e. 'ALC')</TD>
 481                                 </TR>
 482                                 <TR><TD VALIGN=TOP ALIGN=LEFT>Interface Type</TD>
 483                                         <TD VALIGN=TOP ALIGN=CENTER>4</TD>
 484                                         <TD VALIGN=TOP>The type of interface as defined in the description for pcap_datalink() (in network neutral order).</TD>
 485                                 </TR>
 486                                 <TR><TD VALIGN=TOP ALIGN=LEFT>Loopback Flag</TD>
 487                                         <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 488                                         <TD VALIGN=TOP>1 = if the interface is a loopback interface, zero = otherwise.</TD>
 489                                 </TR>
 490                                 <TR><TD VALIGN=TOP ALIGN=RIGHT>count</TD>
 491                                         <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 492                                         <TD VALIGN=TOP># of address entries that follow.
 493                                                 Each entry is a series of bytes in network neutral order.
 494                                                 See the parameter definition above for more details.</TD>
 495                                 </TR>
 496                                 <TR>
 497                                         <TD ALIGN=CENTER ROWSPAN=8 WIDTH=1%>Repeated 'count' number of times.</TD>
 498                                         <TD VALIGN=TOP ALIGN=RIGHT>length</TD>
 499                                         <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 500                                         <TD VALIGN=TOP>The number of octets in the address field that follows.</TD>
 501                                 </TR>
 502                                 <TR><TD VALIGN=TOP ALIGN=LEFT>Address</TD>
 503                                         <TD VALIGN=TOP ALIGN=CENTER>1-255</TD>
 504                                         <TD VALIGN=TOP>The address of this interface (in network neutral order).</TD>
 505                                 </TR>
 506                                 <TR><TD VALIGN=TOP ALIGN=RIGHT>length</TD>
 507                                         <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 508                                         <TD VALIGN=TOP>The number of octets in the netmask field that follows.</TD>
 509                                 </TR>
 510                                 <TR><TD VALIGN=TOP ALIGN=LEFT>Network Mask</TD>
 511                                         <TD VALIGN=TOP ALIGN=CENTER>0-255</TD>
 512                                         <TD VALIGN=TOP>The network mask used on this interface (if applicable) (in network neutral order).</TD>
 513                                 </TR>
 514                                 <TR><TD VALIGN=TOP ALIGN=RIGHT>length</TD>
 515                                         <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 516                                         <TD VALIGN=TOP>The number of octets in the broadcast address field that follows.</TD>
 517                                 </TR>
 518                                 <TR><TD VALIGN=TOP ALIGN=LEFT>Broadcast Address</TD>
 519                                         <TD VALIGN=TOP ALIGN=CENTER>0-255</TD>
 520                                         <TD VALIGN=TOP>The broadcast address of this interface (if applicable) (in network neutral order).</TD>
 521                                 </TR>
 522                                 <TR><TD VALIGN=TOP ALIGN=RIGHT>length</TD>
 523                                         <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 524                                         <TD VALIGN=TOP>The number of octets in the destination address field that follows.</TD>
 525                                 </TR>
 526                                 <TR><TD VALIGN=TOP ALIGN=LEFT>Destination Address</TD>
 527                                         <TD VALIGN=TOP ALIGN=CENTER>0-255</TD>
 528                                         <TD VALIGN=TOP>The destination address of this interface (if applicable) (in network neutral order).</TD>
 529                                 </TR>
 530                                 </TABLE>
 531                 </TR>
 532                 <TR>
 533                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>SMP -> IOP</TD>
 534                         <TD VALIGN=TOP>Close the socket.</TD>
 535                 </TR>
 536                 <TR>
 537                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>IOP -> SMP</TD>
 538                         <TD VALIGN=TOP>Close the socket.</TD>
 539                 </TR>
 540                 <TR><TH COLSPAN=3><HR WIDTH=100%></TH></TR>
 541                 <TR>
 542                         <TD VALIGN=TOP ROWSPAN=2>pcap_open_live()</TD>
 543                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>SMP -> IOP</TD>
 544                         <TD VALIGN=TOP>Open socket, and sends:
 545                                 <P>
 546                                 <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 547                                         <TR>
 548                                         <TH VALIGN=TOP ALIGN=CENTER>Name/<BR>Purpose</TH>
 549                                         <TH VALIGN=TOP ALIGN=CENTER NOWRAP>Size<BR>(in bytes)</TH>
 550                                         <TH VALIGN=TOP ALIGN=CENTER>Description</TH>
 551                                         </TR>
 552                                         <TR>
 553                                                 <TD VALIGN=TOP>Interface ID</TD>
 554                                                 <TD VALIGN=TOP ALIGN=CENTER>'n'</TD>
 555                                                 <TD VALIGN=TOP>'n' octets containing a NULL terminated interface name string.</TD>
 556                                         </TR>
 557                                 </TABLE>
 558                         </TD>
 559                 </TR>
 560                 <TR>
 561                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>IOP -> SMP</TD>
 562                         <TD VALIGN=TOP>Send its NULL terminated error response string.</TD>
 563                 </TR>
 564                 <TR><TH COLSPAN=3><HR WIDTH=100%></TH></TR>
 565                 <TR>
 566                         <TD VALIGN=TOP NOWRAP ROWSPAN=2>pcap_dispatch()<BR>pcap_loop()<BR>pcap_next()<BR>pcap_next_ex()</TD>
 567                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>SMP -> IOP</TD>
 568                         <TD VALIGN=TOP>On the first invocation following a pcap_open_live() or pcap_breakloop() additional information is sent:
 569                                 <P>
 570                                 <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 571                                         <TR>
 572                                         <TH VALIGN=TOP ALIGN=CENTER>Name/<BR>Purpose</TH>
 573                                         <TH VALIGN=TOP ALIGN=CENTER NOWRAP>Size<BR>(in bytes)</TH>
 574                                         <TH VALIGN=TOP ALIGN=CENTER>Description</TH>
 575                                         </TR>
 576                                         <TR>
 577                                                 <TD VALIGN=TOP>command</TD>
 578                                                 <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 579                                                 <TD VALIGN=TOP>'M' (indicating 'monitor start')</TD>
 580                                         </TR>
 581                                         <TR>
 582                                                 <TD VALIGN=TOP>snaplen</TD>
 583                                                 <TD VALIGN=TOP ALIGN=CENTER>4</TD>
 584                                                 <TD VALIGN=TOP>snaplen</TD>
 585                                         </TR>
 586                                         <TR>
 587                                                 <TD VALIGN=TOP>timeout</TD>
 588                                                 <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 589                                                 <TD VALIGN=TOP>timeout value (in milliseconds)</TD>
 590                                         </TR>
 591                                         <TR>
 592                                                 <TD VALIGN=TOP>promiscuous</TD>
 593                                                 <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 594                                                 <TD VALIGN=TOP>A flag indicating that the interface being monitored show operate
 595                                                         in promiscuous mode. [off(0) / on(NZ)]</TD>
 596                                         </TR>
 597                                         <TR>
 598                                                 <TD VALIGN=TOP>direction</TD>
 599                                                 <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 600                                                 <TD VALIGN=TOP>A flag indicating the direction of traffic that should be captuted [both(0) / in(1) / out(2)]</TD>
 601                                         </TR>
 602                                 </TABLE>
 603                         </TD>
 604                 </TR>
 605                 <TR>
 606                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>IOP -> SMP</TD>
 607                         <TD VALIGN=TOP>Sends captured packets.</TD>
 608                 </TR>
 609                 <TR><TH COLSPAN=3><HR WIDTH=100%></TH></TR>
 610                 <TR>
 611                         <TD VALIGN=TOP ROWSPAN=2>pcap_setfilter()</TD>
 612                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>SMP -> IOP</TD>
 613                         <TD VALIGN=TOP>At any time, the SMP can issue a set filter command which contains
 614                                                         an indicator, a count of the number of statements in the filter,
 615                                                         followed by the sequence of filter commands represented as a sequence
 616                                                         of C-style structures.
 617                                 <P>
 618                                 <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 619                                         <TR>
 620                                         <TH VALIGN=TOP ALIGN=CENTER>Name/<BR>Purpose</TH>
 621                                         <TH VALIGN=TOP ALIGN=CENTER NOWRAP>Size<BR>(in bytes)</TH>
 622                                         <TH VALIGN=TOP ALIGN=CENTER>Description</TH>
 623                                         </TR>
 624                                         <TR>
 625                                                 <TD VALIGN=TOP>command</TD>
 626                                                 <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 627                                                 <TD VALIGN=TOP>'F' (indicating 'filter')</TD>
 628                                         </TR>
 629                                         <TR>
 630                                                 <TD VALIGN=TOP>count</TD>
 631                                                 <TD VALIGN=TOP ALIGN=CENTER>4</TD>
 632                                                 <TD VALIGN=TOP>The number of command in the Berkeley Packet Filter that follow.</TD>
 633                                         </TR>
 634                                         <TR>
 635                                                 <TD VALIGN=TOP>BPF program</TD>
 636                                                 <TD VALIGN=TOP ALIGN=CENTER>'n'</TD>
 637                                                 <TD VALIGN=TOP>8 bytes of each command (repeated 'n' times).<BR>
 638                                                                         Each command consists of that C-style structure which contains:
 639                                                         <P>
 640                                                         <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 641                                                                 <TR>
 642                                                                 <TH VALIGN=TOP ALIGN=CENTER>Name/<BR>Purpose</TH>
 643                                                                 <TH VALIGN=TOP ALIGN=CENTER NOWRAP>Size<BR>(in bytes)</TH>
 644                                                                 <TH VALIGN=TOP ALIGN=CENTER>Description</TH>
 645                                                                 </TR>
 646                                                                 <TR>
 647                                                                         <TD VALIGN=TOP>opcode</TD>
 648                                                                         <TD VALIGN=TOP ALIGN=CENTER>2</TD>
 649                                                                         <TD VALIGN=TOP>The command's opcode.</TD>
 650                                                                 </TR>
 651                                                                 <TR>
 652                                                                         <TD VALIGN=TOP>'jt'</TD>
 653                                                                         <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 654                                                                         <TD VALIGN=TOP>The 'jump if true' program counter offset.</TD>
 655                                                                 </TR>
 656                                                                 <TR>
 657                                                                         <TD VALIGN=TOP>'jf'</TD>
 658                                                                         <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 659                                                                         <TD VALIGN=TOP>The 'jump if false' program counter offset.</TD>
 660                                                                 </TR>
 661                                                                 <TR>
 662                                                                         <TD VALIGN=TOP>'k'</TD>
 663                                                                         <TD VALIGN=TOP ALIGN=CENTER>4</TD>
 664                                                                         <TD VALIGN=TOP>The 'other' data field.</TD>
 665                                                                 </TR>
 666                                                         </TABLE>
 667                                                         <P>
 668                                                         Refer to the bpf(4) man page for more details.
 669                                                 </TD>
 670                                         </TR>
 671                                 </TABLE>
 672                         </TD>
 673                 </TR>
 674                 <TR>
 675                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>IOP -> SMP</TD>
 676                         <TD VALIGN=TOP>In return the IOP will send its (possibly empty) NULL terminated error response string.</TD>
 677                 </TR>
 678                 <TR><TH COLSPAN=3><HR WIDTH=100%></TH></TR>
 679                 <TR>
 680                         <TD VALIGN=TOP ROWSPAN=2>pcap_stats()</TD>
 681                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>SMP -> IOP</TD>
 682                         <TD VALIGN=TOP>At any time, the SMP can issue a 'retrieve statistics' command which contains:<BR>
 683                                 <P>
 684                                 <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 685                                         <TR>
 686                                         <TH VALIGN=TOP ALIGN=CENTER>Name/<BR>Purpose</TH>
 687                                         <TH VALIGN=TOP ALIGN=CENTER NOWRAP>Size<BR>(in bytes)</TH>
 688                                         <TH VALIGN=TOP ALIGN=CENTER>Description</TH>
 689                                         </TR>
 690                                         <TR>
 691                                                 <TD VALIGN=TOP>command</TD>
 692                                                 <TD VALIGN=TOP ALIGN=CENTER>1</TD>
 693                                                 <TD VALIGN=TOP>'S' (indicating 'request statistics')</TD>
 694                                         </TR>
 695                                 </TABLE>
 696                         </TD>
 697                 </TR>
 698                 <TR>
 699                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>IOP -> SMP</TD>
 700                         <TD VALIGN=TOP>In return the IOP will send:
 701                                 <P>
 702                                 <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 703                                         <TR>
 704                                         <TH VALIGN=TOP ALIGN=CENTER>Name/<BR>Purpose</TH>
 705                                         <TH VALIGN=TOP ALIGN=CENTER NOWRAP>Size<BR>(in bytes)</TH>
 706                                         <TH VALIGN=TOP ALIGN=CENTER>Description</TH>
 707                                         </TR>
 708                                         <TR>
 709                                                 <TD VALIGN=TOP>ps_recv</TD>
 710                                                 <TD VALIGN=TOP ALIGN=CENTER>4</TD>
 711                                                 <TD VALIGN=TOP>The number of packets that passed the filter.</TD>
 712                                         </TR>
 713                                         <TR>
 714                                                 <TD VALIGN=TOP>ps_drop</TD>
 715                                                 <TD VALIGN=TOP ALIGN=CENTER>4</TD>
 716                                                 <TD VALIGN=TOP>The number of packets that were dropped because the input queue was full,
 717                                                         regardless of whether they passed the filter.</TD>
 718                                         </TR>
 719                                         <TR>
 720                                                 <TD VALIGN=TOP>ps_ifdrop</TD>
 721                                                 <TD VALIGN=TOP ALIGN=CENTER>4</TD>
 722                                                 <TD VALIGN=TOP>The number of packets dropped by the network inteface
 723                                                         (regardless of whether they would have passed the input filter).</TD>
 724                                         </TR>
 725                                 </TABLE>
 726                         </TD>
 727                 </TR>
 728                 <TR><TH COLSPAN=3><HR WIDTH=100%></TH></TR>
 729                 <TR>
 730                         <TD VALIGN=TOP ROWSPAN=1>pcap_close()</TD>
 731                         <TD VALIGN=TOP ALIGN=CENTER NOWRAP>SMP -> IOP</TD>
 732                         <TD VALIGN=TOP>At any time, the SMP can close the TCP session with the IOP.</TD>
 733                 </TR>
 734                 <TR><TH COLSPAN=3><HR WIDTH=100%></TH></TR>
 735         </TABLE>
 736 </UL>
 737
 738 <H3>Interface ID Naming Convention</H3>
 739 <UL>
 740         Each interface within an IOP will be referred to uniquely.  Since an currently contains
 741         8 monitorable WAN ports and a monitorable Ethernet port, the naming convention is:
 742         <P>
 743         <CENTER>
 744         <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 745                 <TR><TH>Interface #</TH>                <TH>Type</TH>                                   <TH>Name</TH></TR>
 746                 <TR><TD ALIGN=CENTER>1</TD>             <TD ALIGN=CENTER>WAN</TD>               <TD ALIGN=CENTER>wan0</TD></TR>
 747                 <TR><TD ALIGN=CENTER>2</TD>             <TD ALIGN=CENTER>WAN</TD>               <TD ALIGN=CENTER>wan1</TD></TR>
 748                 <TR><TD ALIGN=CENTER>3</TD>             <TD ALIGN=CENTER>WAN</TD>               <TD ALIGN=CENTER>wan2</TD></TR>
 749                 <TR><TD ALIGN=CENTER>4</TD>             <TD ALIGN=CENTER>WAN</TD>               <TD ALIGN=CENTER>wan3</TD></TR>
 750                 <TR><TD ALIGN=CENTER>5</TD>             <TD ALIGN=CENTER>WAN</TD>               <TD ALIGN=CENTER>wan4</TD></TR>
 751                 <TR><TD ALIGN=CENTER>6</TD>             <TD ALIGN=CENTER>WAN</TD>               <TD ALIGN=CENTER>wan5</TD></TR>
 752                 <TR><TD ALIGN=CENTER>7</TD>             <TD ALIGN=CENTER>WAN</TD>               <TD ALIGN=CENTER>wan6</TD></TR>
 753                 <TR><TD ALIGN=CENTER>8</TD>             <TD ALIGN=CENTER>WAN</TD>               <TD ALIGN=CENTER>wan7</TD></TR>
 754                 <TR><TD ALIGN=CENTER>9</TD>             <TD ALIGN=CENTER>Ethernet</TD>  <TD ALIGN=CENTER>eth0</TD></TR>
 755                 <TR><TD ALIGN=CENTER>10</TD>    <TD ALIGN=CENTER>Ethernet</TD>  <TD ALIGN=CENTER>eth1</TD></TR>
 756         </TABLE>
 757         </CENTER>
 758 </UL>
 759
 760 <H3>Packet Trace Data Format</H3>
 761 <UL>
 762         The format of the trace data that is sent to the SMP follows a portion of the libpcap file format
 763         and is summarized here.  This format specifies the generic requirements needed to
 764         be able to decode packets, but does not cover ACN specifics such as custom MAC addressing
 765         and WAN protocol support.
 766         <P>
 767
 768         Although a libpcap file begins with a global header followed by zero or
 769         more records for each captured packet, trace data sent to the SMP does NOT begin with a global header.
 770         A trace sequence looks like this:
 771         <P>
 772         <TABLE>
 773                 <TR>
 774                         <TD STYLE="background-color: #c0FFc0">&nbsp;[Packet Header]&nbsp;</TD>
 775                         <TD STYLE="background-color: #c0FFc0">&nbsp;[Packet Data]&nbsp;</TD>
 776                         <TD STYLE="background-color: #c0c0FF">&nbsp;[Packet Header]&nbsp;</TD>
 777                         <TD STYLE="background-color: #c0c0FF">&nbsp;[Packet Data]&nbsp;</TD>
 778                         <TD STYLE="background-color: #e0c0c0">&nbsp;[Packet Header]&nbsp;</TD>
 779                         <TD STYLE="background-color: #e0c0c0">&nbsp;[Packet Data]&nbsp;</TD>
 780                         <TD>...</TD>
 781                 </TR>
 782         </TABLE>
 783
 784 <H4>Packet Header</H4>
 785         <UL>
 786                 Each captured packet starts with a header that contains the following values
 787                 (in network neutral order):
 788
 789                 <FONT SIZE=-1>
 790                 <PRE>
 791  uint32 tv_sec;  /* timestamp seconds */
 792  uint32 tv_usec; /* timestamp microseconds */
 793  uint32 caplen;  /* number of octets in the following packet */
 794  uint32 len;     /* original length of packet on the wire */
 795                 </PRE>
 796                 </FONT>
 797
 798                 <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 799                         <TR>
 800                                 <TD VALIGN=TOP>tv_sec</TD>
 801                                 <TD>The date and time when this packet was captured.
 802                                         This value is in seconds since January 1, 1970 00:00:00 GMT;
 803                                         this is also known as a UN*X time_t. You can use the ANSI C
 804                                         <em>time()</em> function from <em>time.h</em> to get this value,
 805                                         but you might use a more optimized way to get this timestamp value.
 806                                         If this timestamp isn't based on GMT (UTC), use <em>thiszone</em>
 807                                         from the global header for adjustments.</TD>
 808                         </TR>
 809                         <TR>
 810                                 <TD VALIGN=TOP>tv_usec</TD>
 811                                 <TD>The microseconds when this packet was captured, as an offset to <em>ts_sec</em>.
 812                                         <B>Beware: </B>this value must never reach 1 second (1,000,000),
 813                                         in this case <em>ts_sec</em> must be increased instead!</TD>
 814                         </TR>
 815                         <TR>
 816                                 <TD VALIGN=TOP>caplen</TD>
 817                                 <TD>The number of bytes actually provided in the capture record.
 818                                         This value should never become larger than <em>len</em> or the
 819                                         <em>snaplen</em> value specified during the capture.</TD>
 820                         </TR>
 821                         <TR>
 822                                 <TD VALIGN=TOP>len</TD>
 823                                 <TD>The length of the packet "on the wire" when it was captured.
 824                                         If <em>caplen</em> and <em>len</em> differ, the actually
 825                                         saved packet size was limited by the value of <em>snaplen</em> specified
 826                                         during one of the capture directives such as pcap_dispatch().</TD>
 827                         </TR>
 828                 </TABLE>
 829         </UL>
 830
 831 <H4>Packet Data</H4>
 832         <UL>
 833         The actual packet data will immediately follow the packet header as a sequence of <em>caplen</em> octets.
 834         Depending on the DLT encoding number assigned to the interface, the packet data will contain an additional
 835         custom header used to convey WAN port related information.
 836         </UL>
 837
 838 <H4>ACN Custom Packet Header</H4>
 839         <UL>
 840         PCAP, Wireshark and Tcpdump enhancements have been added to the ACN to support
 841         monitoring of its ports, however each of these facilities were focused on capturing
 842         and displaying traffic from LAN interfaces.  The SITA extentions to these facilities
 843         are used to also provide the ability to capture, filter, and display information from
 844         an ACN's WAN ports.
 845         <P>
 846         Although each packet follows the standard libpcap format, since there are
 847         two types of interfaces that can be monitored, the format of the data
 848         packet varies slightly.
 849         <P>
 850         <UL TYPE=DISC>
 851                 <LI>For Ethernet (like) devices, the packet format is unchanged from the standard Pcap format.
 852                 <LI>For WAN devices, the packet contains a 5 byte header that preceeds the actual captured data
 853                         described by the following table:
 854         </UL>
 855         <P>
 856         <CENTER>
 857         <TABLE BORDER=1 CELLSPACING=0 CELLPADDING=3>
 858         <TR>    <TH>Octet</TH>
 859                         <TH>Name</TH>
 860                         <TH>Mask/Value</TH>
 861                         <TH COLSPAN=2>Definition</TH>           </TR>
 862
 863         <TR>    <TH VALIGN=TOP ALIGN=CENTER ROWSPAN=3>0</TH>
 864                         <TH VALIGN=TOP ALIGN=CENTER ROWSPAN=3>Control / Status</TH>
 865
 866                         <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxxxxx0</FONT></TD>
 867                         <TD>Transmitted by capture device</TD>
 868                         <TD ROWSPAN=2 ALIGN=CENTER>(see 'Errors' octets)</TD>                                                   </TR>
 869         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxxxxx1</FONT></TD>
 870                         <TD>Received by capture device</TD>                                                                                             </TR>
 871         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">1xxxxxxx</FONT></TD>
 872                         <TD COLSPAN=2>No buffer was available during capture of previous packet.</TD>   </TR>
 873
 874         <TR>    <TH VALIGN=TOP ALIGN=CENTER ROWSPAN=8>1</TH>
 875                         <TH VALIGN=TOP ALIGN=CENTER ROWSPAN=8>Signals</TH>
 876
 877                         <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxxxxx1</FONT></TD>   <TD COLSPAN=2>DSR asserted</TD>         </TR>
 878         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxxxx1x</FONT></TD>   <TD COLSPAN=2>DTR asserted</TD>         </TR>
 879         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxxx1xx</FONT></TD>   <TD COLSPAN=2>CTS asserted</TD>         </TR>
 880         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxx1xxx</FONT></TD>   <TD COLSPAN=2>RTS asserted</TD>         </TR>
 881         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxx1xxxx</FONT></TD>   <TD COLSPAN=2>DCD asserted</TD>         </TR>
 882         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xx1xxxxx</FONT></TD>   <TD COLSPAN=2>Undefined</TD>            </TR>
 883         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">x1xxxxxx</FONT></TD>   <TD COLSPAN=2>Undefined</TD>            </TR>
 884         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">1xxxxxxx</FONT></TD>   <TD COLSPAN=2>Undefined</TD>            </TR>
 885
 886         <TR>    <TH VALIGN=TOP ALIGN=CENTER ROWSPAN=9>2</TH>
 887                         <TH VALIGN=TOP ALIGN=CENTER ROWSPAN=9>Errors<BR>(octet 1)</TH>
 888
 889                         <TH>&nbsp;</TH>                                                                                                                 <TH>Tx</TH>                                             <TH>Rx</TH>                             </TR>
 890         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxxxxx1</FONT></TD>   <TD>Underrun</TD>                               <TD>Framing</TD>                </TR>
 891         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxxxx1x</FONT></TD>   <TD>CTS Lost</TD>                               <TD>Parity</TD>                 </TR>
 892         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxxx1xx</FONT></TD>   <TD>UART Error</TD>                             <TD>Collision</TD>              </TR>
 893         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxx1xxx</FONT></TD>   <TD>Re-Tx Limit Reached</TD>    <TD>Long Frame</TD>             </TR>
 894         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxx1xxxx</FONT></TD>   <TD>Undefined</TD>                              <TD>Short Frame</TD>    </TR>
 895         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xx1xxxxx</FONT></TD>   <TD>Undefined</TD>                              <TD>Undefined</TD>              </TR>
 896         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">x1xxxxxx</FONT></TD>   <TD>Undefined</TD>                              <TD>Undefined</TD>              </TR>
 897         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">1xxxxxxx</FONT></TD>   <TD>Undefined</TD>                              <TD>Undefined</TD>              </TR>
 898
 899         <TR>    <TH VALIGN=TOP ALIGN=CENTER ROWSPAN=9>3</TH>
 900                         <TH VALIGN=TOP ALIGN=CENTER ROWSPAN=9>Errors<BR>(octet 2)</TH>
 901
 902                         <TH>&nbsp;</TH>                                                                                                                 <TH>Tx</TH>                     <TH>Rx</TH>                                             </TR>
 903         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxxxxx1</FONT></TD>   <TD>Undefined</TD>      <TD>Non-Octet Aligned</TD>              </TR>
 904         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxxxx1x</FONT></TD>   <TD>Undefined</TD>      <TD>Abort Received</TD>                 </TR>
 905         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxxx1xx</FONT></TD>   <TD>Undefined</TD>      <TD>CD Lost</TD>                                </TR>
 906         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxxx1xxx</FONT></TD>   <TD>Undefined</TD>      <TD>Digital PLL Error</TD>              </TR>
 907         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xxx1xxxx</FONT></TD>   <TD>Undefined</TD>      <TD>Overrun</TD>                                </TR>
 908         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">xx1xxxxx</FONT></TD>   <TD>Undefined</TD>      <TD>Frame Length Violation</TD> </TR>
 909         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">x1xxxxxx</FONT></TD>   <TD>Undefined</TD>      <TD>CRC Error</TD>                              </TR>
 910         <TR>    <TD VALIGN=TOP ALIGN=CENTER><FONT FACE="COURIER">1xxxxxxx</FONT></TD>   <TD>Undefined</TD>      <TD>Break Received</TD>                 </TR>
 911
 912         <TR>    <TH VALIGN=TOP ALIGN=CENTER ROWSPAN=12>4</TH>
 913                         <TH VALIGN=TOP ALIGN=CENTER>Protocol</TH>
 914
 915                         <TD COLSPAN=3>
 916                                 <CENTER>
 917                                 <TABLE BORDER=0 CELLPADDING=0 CELLSPACING=0>
 918                                         <TR VALIGN=BOTTOM><TD ALIGN=CENTER>0x01</TD>    <TD>-</TD>      <TD>LAPB (BOP)                          <SUP>&nbsp;</SUP>       </TD>   </TR>
 919                                         <TR VALIGN=BOTTOM><TD ALIGN=CENTER>0x02</TD>    <TD>-</TD>      <TD>Ethernet                            <SUP>1</SUP>            </TD>   </TR>
 920                                         <TR VALIGN=BOTTOM><TD ALIGN=CENTER>0x03</TD>    <TD>-</TD>      <TD>Async (Interrupt IO)        <SUP>&nbsp;</SUP>       </TD>   </TR>
 921                                         <TR VALIGN=BOTTOM><TD ALIGN=CENTER>0x04</TD>    <TD>-</TD>      <TD>Async (Block IO)            <SUP>&nbsp;</SUP>       </TD>   </TR>
 922                                         <TR VALIGN=BOTTOM><TD ALIGN=CENTER>0x05</TD>    <TD>-</TD>      <TD>IPARS                                       <SUP>&nbsp;</SUP>       </TD>   </TR>
 923                                         <TR VALIGN=BOTTOM><TD ALIGN=CENTER>0x06</TD>    <TD>-</TD>      <TD>UTS                                         <SUP>&nbsp;</SUP>       </TD>   </TR>
 924                                         <TR VALIGN=BOTTOM><TD ALIGN=CENTER>0x07</TD>    <TD>-</TD>      <TD>PPP (HDLC)                          <SUP>&nbsp;</SUP>       </TD>   </TR>
 925                                         <TR VALIGN=BOTTOM><TD ALIGN=CENTER>0x08</TD>    <TD>-</TD>      <TD>SDLC                                        <SUP>&nbsp;</SUP>       </TD>   </TR>
 926                                         <TR VALIGN=BOTTOM><TD ALIGN=CENTER>0x09</TD>    <TD>-</TD>      <TD>Token Ring                          <SUP>1</SUP>            </TD>   </TR>
 927                                         <TR VALIGN=BOTTOM><TD ALIGN=CENTER>0x10</TD>    <TD>-</TD>      <TD>I2C                                         <SUP>&nbsp;</SUP>       </TD>   </TR>
 928                                         <TR VALIGN=BOTTOM><TD ALIGN=CENTER>0x11</TD>    <TD>-</TD>      <TD>DPM Link                            <SUP>&nbsp;</SUP>       </TD>   </TR>
 929                                         <TR VALIGN=BOTTOM><TD ALIGN=CENTER>0x12</TD>    <TD>-</TD>      <TD>Frame Relay (BOP)           <SUP>&nbsp;</SUP>       </TD>   </TR>
 930                                 </TABLE>
 931                                 </CENTER>
 932                                 <P>
 933                                 <STRONG>Note 1:</STRONG>
 934                                 Ethernet and Token Ring frames will never be sent as DLT_SITA (with the 5 octet header),
 935                                 but will be sent as their corresponding DLT types instead.
 936                         </TD>
 937         </TR>
 938         </TABLE>
 939         </CENTER>
 940 </UL>
 941 <P>
 942 </UL>
 943 </UL>