Chapter 29: Internet Protocol Version 4 Packet Routing
340
Section VII: Routing
Internet Control Message Protocol (ICMP)
ICMP allows routers to send error and control messages to other routers
or hosts. It provides the communication between IP software on one
system and IP software on another. The switch implements the ICMP
functions listed in Table 94.
Table 94. ICMP Messages Implemented on the AT-9400 Switch
ICMP Packet (Type)
Switch Response
Echo reply (0)
This is used to implement the
“ping” command common to most
UNIX and TCP implementations.
The switch sends out an “Echo
reply” packet in response to an
“Echo request.”
Destination unreachable (3)
This message is sent out when the
switch drops a packet because it
did not have a route to the
destination.
Source Quench (4)
The switch will send a “Source
Quench” if it must drop a packet
due to limited internal resources.
This could be because the source
was sending data too fast to be
forwarded.
Redirect (5)
The switch will issue a “redirect”
packet to inform a local host that
its target is located on the same
LAN (no routing is required) or
when it detects a host using a non-
optimal route (usually because a
link has failed or changed its
status).
Echo request (8)
This is related to (1) and results in
an “echo reply” packet being sent.
The switch can also generate an
“echo request” packet as a result
of the PING command.
Summary of Contents for AT-S63
Page 14: ...Figures 14 ...
Page 18: ...Tables 18 ...
Page 28: ...28 Section I Basic Operations ...
Page 58: ...Chapter 1 Overview 58 ...
Page 76: ...Chapter 2 AT 9400Ts Stacks 76 Section I Basic Operations ...
Page 96: ...Chapter 5 MAC Address Table 96 Section I Basic Operations ...
Page 114: ...Chapter 8 Port Mirror 114 Section I Basic Operations ...
Page 116: ...116 Section II Advanced Operations ...
Page 146: ...Chapter 12 Access Control Lists 146 Section II Advanced Operations ...
Page 176: ...Chapter 14 Quality of Service 176 Section II Advanced Operations ...
Page 196: ...196 Section III Snooping Protocols ...
Page 204: ...Chapter 18 Multicast Listener Discovery Snooping 204 Section III Snooping Protocols ...
Page 216: ...Chapter 20 Ethernet Protection Switching Ring Snooping 216 Section III Snooping Protocols ...
Page 218: ...218 Section IV SNMPv3 ...
Page 234: ...234 Section V Spanning Tree Protocols ...
Page 268: ...268 Section VI Virtual LANs ...
Page 306: ...Chapter 27 Protected Ports VLANs 306 Section VI Virtual LANs ...
Page 320: ...320 Section VII Internet Protocol Routing ...
Page 360: ...Chapter 30 BOOTP Relay Agent 360 Section VII Routing ...
Page 370: ...Chapter 31 Virtual Router Redundancy Protocol 370 Section VII Routing ...
Page 372: ...372 Section VIII Port Security ...
Page 402: ...Chapter 33 802 1x Port based Network Access Control 402 Section VIII Port Security ...
Page 404: ...404 Section IX Management Security ...
Page 436: ...Chapter 36 PKI Certificates and SSL 436 Section IX Management Security ...
Page 454: ...Chapter 38 TACACS and RADIUS Protocols 454 Section IX Management Security ...
Page 462: ...Chapter 39 Management Access Control List 462 Section IX Management Security ...
Page 532: ...Appendix D MIB Objects 532 ...