Subject: Problem in RIP summarization

From: "Karthikeyan Subramaniam" <[email-masked]>
Date: 30 Jul 2002 08:39:15 -0000

Hello All,

    I have some problem in RIP route summarzation.As per RFC 2453, 
auto-summarization is done in order to reduce the total number of 
route entries. But Cisco also does summarization which is on 
interface basis. Will it be advisable to do route summarization on 
interfaces basis also, as this was not discussed in RFC?

I have some contradictions in Cisco implementation of 
summarization on interfaces basis. Some of the issues are as 
discussed below. All the references are picked up from Cisco 
document

http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/ip_c/ipcprt2/1cdrip.htm

Interface summary address overrides the Auto Summary address.
 	The AutoSummary will override the configured summary-address 
feature on a given interface except when the following condition 
is true:
-	The configured interface summary-address and the IP address of 
the configured interface share the same major network (the 
classful, nonsubnetted portion of the IP address).
-	Split horizon is not enabled on the interface.

Issue 1: On what basis the ip summary address overrides the auto 
summary address, if the major net of interface address and ip 
summary address matches?

Issue 2: On what scenario, there can be a problem when split 
horizon and auto-summary are enabled?

Issue 3: There is a contradiction is Cisco document saying 
auto-summary and split horizon (excluding non-broadcast networks 
)is enabled by default. But the primary reason for 
auto-summarization to come into effect is split horizon should be 
disabled.

I would appreciate if I can get solutions addressing above 
issues.

Thanks in advance.
With Regards,
S.Karthikeyan.

_______________________________________________
routing-discussion mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/routing-discussion