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Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
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Chapter 38 Configuring IP Unicast Routing
Configuring IP Addressing
Beginning in privileged EXEC mode, follow these steps to define a default gateway (router) when IP
routing is disabled:
Use the
no ip default-gateway
global configuration command to disable this function.
ICMP Router Discovery Protocol (IRDP)
Router discovery allows the switch to dynamically learn about routes to other networks by using ICMP
Router Discovery Protocol (IRDP). Hosts use IRDP 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 receive Routing Information Protocol (RIP) 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 more 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 change any of these parameters.
Beginning in privileged EXEC mode, follow these steps to enable and configure IRDP on an interface:
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
ip default-gateway
ip-address
Set up a default gateway (router).
Step 3
end
Return to privileged EXEC mode.
Step 4
show ip redirects
Display the address of the default gateway router to verify the
setting.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
interface
interface-id
Enter interface configuration mode, and specify the Layer 3 interface to
configure.
Step 3
ip irdp
Enable IRDP processing on the interface.
Step 4
ip irdp multicast
(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.
Step 5
ip irdp holdtime
seconds
(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.
