10 • ICMP
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Introduction
When networking problems or undesirable conditions occur, the ICMP protocol is used for communicating
control or error information plus testing. The statistics listed on the DACS ICMP window (see figure 22) com-
prise those contained in RFC 792—Internet Control Message Protocol (ICMP). Implementation of the ICMP
group is mandatory for all TCP/IP networks. RFC 1312—ICMP Group of MIB-II Variables—provides the
definitions of these variables. It is important to remember that any RFC can be superseded by a newer.
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Click on ICMP under the Configuration Menu to monitor DACS ICMP statistics.
Block ICMP redirects (boxBLockIcmpRedirects)
The two options for “Block ICMP Redirects” either allow the reception of ICMP Redirect messages [allowre-
directs(0)] or block the reception of ICMP Redirect messages [stopredirects(1)]. The recommended configura-
tion is to block the ICMP redirect messages because in some instances they could alter the routing table with
undesirable effects, which is considered a breach of security.
ICMP Receive/Send Messages window
The ICMP window displays the ICMP message counters. ICMP messages are displayed in the window as col-
umns comprising two types of messages:
•
Messages received by the DACS (InMibVariable)
•
Messages sent by the DACS (OutMibVariable)
The numbers following the parameters can be a good source of what is happening on the network to point out
potential problems. Both gateways (routers) and hosts can send ICMP messages.
Total Received (icmpInMsgs)
The total number of ICMP messages which the 3092 Multiplexer has received. Note that this counter includes
all those counted by icmpInErrors (see “w/Errors (icmpInErrors, icmpOutErrors)” on page 67).
Summary of Contents for 3092
Page 18: ...About this guide 16...
Page 22: ...1 Introduction 20 8 4 9...
Page 44: ...5 DS0 Mapping 42 C 4...
Page 48: ...6 Clocking 46...
Page 56: ...7 iDSL Port Configuration 54...
Page 66: ...9 Filter IP 64...
Page 89: ...2 3 87 12 TCP finWait1 6 finWait2 7 closeWait 8 lastAck 9 closing 10 timeWait 11 deleteTCB 12...
Page 90: ...12 TCP 88 2 3...
Page 94: ...13 UDP 92...
Page 100: ...14 RIP Version 2 98 7 2 3...
Page 106: ...15 SNMP 104...
Page 118: ...16 System 116 D 4 1...
Page 148: ...18 T1 E1 Link 146 D...
Page 152: ...19 T1 E1 Assignment 150 68 6...
Page 158: ...21 License 156...
Page 162: ...A RJ 21X Wiring Color Chart 160...