From: Donny MATEO (donny.mateo@sg.ca-indosuez.com)
Date: Mon Mar 10 2003 - 06:53:55 GMT-3
ok I'll try and see if I can remember this correctly
.
Case 1: Primary and secondary address are on different major network.
a. Splithorizon enabled => consider the other as a different network so send only summary of those different network.(primary and secondary)
b. Splithorizon disabled => same.
example :
int e0
ip addr 10.1.1.1 255.255.255.0
ip addr 11.1.1.1 255.255.255.0 secondary
result
a. Splithorizon enabled => primary will source 10.1.1.0/24 (any another other/24 on the same major net) and 11.0.0.0/8, secondary will source 11.1.1.0/24 (plus all /24 on the same major network) and 10.0.0.0/8
b. Splithorizon disabled => roughly the same
Case 2: Primary and secondary address are on the same major network
a. Splithorizon enabled => send primary and secondary subnets. different major net, summarized to boundary. Secondary will not source any update.
b. Splithorizon disabled => heck cares, sends everything you got (secondary and primary). Different major net summarized.
example
int e0
ip addr 10.1.1.1 255.255.255.0
ip addr 10.1.2.2 255.255.255.0 sec
result
a. Splithorizon enabled => primary will source 10.1.1.0/24 and 10.1.2.0/24. Secondary sourced nothing
b. Splithorizon disabled => both primary and secondary will source 10.1.1.0/24 (and all /24 with the same major net 10.0.0.0/8) and 10.1.2.0/24 (and all /24 with the same major net 11.0.0.0/8).
In short, if you use secondary technique to force RIP to send subnetted subnet update with the same major net, disable splithorizon and filter incoming routes (or the outgoing routes on the other peer router).
If the VLSM route is not of the same major net, you can't do anything with secondary. It's all going to be suppressed. This is default behaviour for RIP version 1. If you still insist, change the rip behaviour on the interface to version 2. something
like:
int e0
ip rip send version 2
end
This will works because RIP by default will accept version 1 and 2 update. Just becarefull when you don't have access to the other end router (in our case backbone router), make sure you can get a reply when you try and extended ping from the VLSM subnet.
Regards,
Donny
rionaldi@cbn.net.
id To: ccielab@groupstudy.com
Sent by: cc:
nobody@groupstudy Subject: RIP Updates behaviour with Secondary interface
.com
10-03-2003 16:17
Please respond to
rionaldi
can anyone simplify this link content and give me examples on this matter
www.cisco.com/warp/public/105/41.html
Regards,
Prio
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