Internet Protocol (IP) Addressing and Protocols
©2008 Allied Telesis Inc. All rights reserved.
22.10
AlliedWare Plus
TM
Operating System Software Reference C613-50003-00 REV E
Software Version 5.2.1
Solicitation
message
A router solicitation is an ICMP (type 10) message containing:
■
source Address: an IP address belonging to the interface from which the message is sent
■
destination Address: the configured Solicitation Address, and
■
Time-to-Live: 1 if the Destination Address is an IP multicast address; at least 1 otherwise.
Advertisement
interval
The router advertisement interval is the time between router advertisements. For the first few
advertisements sent from an interface (up to 3), your device sends the router advertisements at
intervals of at most 16 seconds. After these initial transmissions, it sends router advertisements
at random intervals between the minimum and maximum intervals that the user configures, to
reduce the probability of synchronization with the advertisements from other routers on the
same link. By default, the minimum is 450 seconds (7.5 minutes), and the maximum is 600
seconds (10 minutes).
Preference level
The preference level is the preference of the advertised address as a default router address
relative to other router addresses on the same subnet. By default, all routers and layer 3
switches have the same preference level, zero. While it is entered as a decimal from 0 to
2147483647, it is encoded in router advertisements as a twos-complement hex integer from
0x8000000 to 0x7fffffff. A higher preference level is preferred over a lower value.
Lifetime
The lifetime of a router advertisement is how long the information in the advertisement is valid.
By default, the lifetime of all advertisements is 1800 seconds (30 minutes).
Address type
Your device can send its router advertisements using either a broadcast or multicast destination
address. By default, your device sends router advertisements using the all-systems multicast
address (224.0.0.1). However, on networks where the hosts do not support IP multicast you
must use the broadcast address (255.255.255.255). To change the address type to broadcast
on an interface, use the command:
To change the address type back to multicast, use the
no
form of the above command, or use
the command:
Configuration
procedure
Do the following to configure your device to send router advertisements.
1.
Enter the interface to advertise.
Enter the configuration mode for the interface, using the command:
2.
Change the address type.
By default, your device sends router advertisements using a multicast destination address. If
hosts on your network do not support this, change the address type to broadcast, using
the command:
3.
Configure the advertisement interval and lifetime.
By default, your device sends router advertisements every 7.5 to 10 minutes, with a
lifetime of 30 minutes. These settings are likely to work well in most situations, and will not
cause a large amount of extra traffic, even if there are several routers on the LAN. If you
change these settings, keep the following proportions:
awplus(config-if)#
ip irdp broadcast
awplus(config-if)#
ip irdp multicast
awplus(config)#
ip interface IFNAME
awplus(config-if)#
ip irdp broadcast
lifetime=3 x maxadvertisementinterval
minadvertisementinverval=0.75 x maxadvertisementinterval