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IPLink Software Configuration Guide
ICMP message processing
The IP suite offers a number of services that control and manage IP connections. The Internet Control Mes-
sage Protocol (ICMP) provides many of these services. Routers send ICMP messages to hosts or other routers
when a problem is discovered with the Internet header. For detailed information on ICMP, see RFC 792.
IPLink software supports the following ICMP message processing features:
•
ICMP redirect messages
•
Router advertisement broadcast message
ICMP redirect messages
Routes are sometimes less than optimal. For example, the router may be forced to resend a packet through the
same interface on which it was received. In this case, the IPLink software application software sends an ICMP
redirect message to the originator of the packet telling the originator that the router is on a subnet directly con-
nected to the receiving device, and that it must forward the packet to another system on the same subnet. The
software sends an ICMP redirect message to the originator of the packet because the originating host presum-
ably could have sent that packet to the next hop without involving this device at all. The redirect message
instructs the sender to remove the receiving device from the route and substitute a specified device representing
a more direct path. This feature is enabled by default.
IPLink software ICMP message processing offers two options for host route redirects:
•
accept—accepts ICMP redirect messages
•
send—sends ICMP redirect messages
Mode: Interface
Step
1
node(ctx-ip)[router]#interface name
2
node(if-ip)[name]#icmp redirect { accept | send} Enables to send or accept ICMP redirect
Example: ICMP redirect messages
The following example shows how to configure ICMP messages processing to accept ICMP redirect messages
on the IP interface lan. Use the following commands in IP context configuration mode.
IPLink(ctx-ip)[router]#interface lan
IPLink(if-ip)[lan]#icmp redirect accept
Router advertisement broadcast message
This message configures the behavior of the router when receiving an ICMP router solicitation message, and
determines if the router shall send periodic ICMP router advertisement messages or not.
By default, ICMP router advertisement messages are sent, either as a reply to ICMP router solicitation mes-
sages or periodically. If the feature is disabled, ICMP router advertisement messages are not sent in any case,
neither as a reply to ICMP router solicitation messages nor periodically.
Software IP interface configuration task list
Command
11 • IP interface configuration
Purpose
Selects the interface name for ICMP mes-
sage processing configuration
messages
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Troubleshooting
