Preventing Routing Loops In Rip; Rip Distribution Access Lists - Avaya G350 Administration

Configuring the router
Configuring RIP

Preventing routing loops in RIP

You can use the following features in RIP to help avoid routing loops:
•
Split-horizon
•
Poison-reverse
The split-horizon technique prevents information about routes from exiting the router interface through
which the information was received. This prevents small routing loops. Use the
command to enable the split-horizon mechanism. Use the
horizon mechanism. By default, split-horizon is enabled.
Poison-reverse updates explicitly indicate that a network or subnet is unreachable. Poison-reverse
updates are sent to defeat large routing loops. Use the
split-horizon with poison-reverse on an interface. Use the
poison-reverse mechanism.

RIP distribution access lists

RIP distribution access lists consist of rules that specify how a router distributes and accepts RIP routing
information from other routers. Before sending an update, the router consults an access list to determine
if it should include specific routes in the update. When receiving an update, the router first checks a set of
rules which apply to incoming updates to determine if it should insert those routes into its routing table.
You can assign the rules per interface and per direction.
Up to 99 RIP distribution access lists can be configured on the Avaya G350 Media Gateway.
For example: To configure RIP distribution access list number 10 permitting distribution and learning of
network 10.10.0.0:
1
Enter the command:
The default action of the access list is deny and can be changed using the
default-action
NOTE:
Whenever at least one permit rule exists, distributing and learning of all the remaining
networks is denied, unless specifically permitted by another rule.
2
Apply the distribution list created in Step 1 by performing the following procedure within the
router rip
— Enter the
updates received on all interfaces.
— Enter the
updates received on interface 'FastEthernet 6/1'.
— Enter the
updates.
— Enter the
updates that were learned from OSPF (redistributed from OSPF into RIP).
If no distribution access list is defined, learning and advertising is allowed for all of the routing
information. This is the default.
150
ip distribution access-list 10 1 permit 10.10.0.0 0.0.255.255
command.
context:
distribution-list 10 in
distribution-list 10 in FastEthernet 6/1
distribution-list 10 out
distribution-list 10 out ospf
form of this command to disable the split-
no
ip rip poison-reverse
form of this command to disable the
no
command to apply list number 10 created in Step 1 on all
command to apply Access List 10 on
command to apply Access List 10 to all advertised
command to apply Access List 10 to all advertised
Administration of the Avaya G350 Media Gateway
ip rip split-horizon
command to enable
ip distribution access-
June 2004