Icmp Router Discovery Protocol (Irdp) - Cisco WS-C3560-48PS-S Software Configuration Manual

Configuring IP Addressing

ICMP Router Discovery Protocol (IRDP)

Router discovery allows the switch to dynamically learn about routes to other networks using IRDP.
IRDP allows hosts to locate routers. When operating as a client, the switch generates router discovery
packets. When operating as a host, the switch receives router discovery packets. The switch can also
listen to Routing Information Protocol (RIP) and Interior Gateway Routing Protocol (IGRP) routing
updates and use this information to infer locations of routers. The switch does not actually store the
routing tables sent by routing devices; it merely keeps track of which systems are sending the data. The
advantage of using IRDP is that it allows each router to specify both a priority and the time after which
a device is assumed to be down if no further packets are received.
Each device discovered becomes a candidate for the default router, and a new highest-priority router is
selected when a higher priority router is discovered, when the current default router is declared down,
or when a TCP connection is about to time out because of excessive retransmissions.
The only required task for IRDP routing on an interface is to enable IRDP processing on that interface.
When enabled, the default parameters apply. You can optionally change any of these parameters.
Beginning in privileged EXEC mode, follow these steps to enable and configure IRDP on an interface:
Command
Step 1
configure terminal
Step 2 interface interface-id
Step 3 ip irdp
Step 4
ip irdp multicast
Step 5 ip irdp holdtime seconds
Step 6 ip irdp maxadvertinterval seconds
Step 7 ip irdp minadvertinterval seconds
Step 8 ip irdp preference number
Step 9 ip irdp address address [number]
Step 10 end
Step 11
show ip irdp
Step 12 copy running-config startup-config
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Purpose
Enter global configuration mode.
Enter interface configuration mode, and specify the Layer 3 interface to
configure.
Enable IRDP processing on the interface.
(Optional) Send IRDP advertisements to the multicast address
(224.0.0.1) instead of IP broadcasts.
Note This command allows for compatibility with Sun Microsystems
Solaris, which requires IRDP packets to be sent out as multicasts.
Many implementations cannot receive these multicasts; ensure
end-host ability before using this command.
(Optional) Set the IRDP period for which advertisements are valid. The
default is three times the maxadvertinterval value. It must be greater
than maxadvertinterval and cannot be greater than 9000 seconds. If you
change the maxadvertinterval value, this value also changes.
(Optional) Set the IRDP maximum interval between advertisements. The
default is 600 seconds.
(Optional) Set the IRDP minimum interval between advertisements. The
default is 0.75 times the maxadvertinterval. If you change the
maxadvertinterval, this value changes to the new default (0.75 of
maxadvertinterval).
(Optional) Set a device IRDP preference level. The allowed range is –2
31
to 2 . The default is 0. A higher value increases the router preference
level.
(Optional) Specify an IRDP address and preference to proxy-advertise.
Return to privileged EXEC mode.
Verify settings by displaying IRDP values.
(Optional) Save your entries in the configuration file.
Chapter 30 Configuring IP Unicast Routing
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