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isis question

banlan.chen
Level 1
Level 1

Hi All,

I have a question about summarization in ISIS. when I enable summary-address on the L1/L2 router, it will generate a static route to null interface and the summary route will only send to other area's L1/L2 router. Is it normal? I use IOS 12.2.

Thanks in advance.

2 Replies 2

rsissons
Level 5
Level 5

This is normal. It means that any traffic sent to this router via the summary route, for which this router does not have an explicit route, will be sent to the null interface, ie dropped.

Hi Rona,

Thank you for your kind reply. Would please tell me from which version IOS there is a static route to null interface in routeing table, when I use summarization in OSPF or ISIS environment. As I know before, only EIGRP can generate this kind of route automatically.

Thanks again.

Banlan