EIGRP: why is AD90 set to a summary-route? I would expect AD 5

Hi All,

Ïn the "EIGRP Summarization" ATL summarization is demonstrated. I am greatly surprised the the generated summary route has an AD of 90 set. (you can see this in the verification section)

I started playing around with summarization, but I can not manage to generate an AD of 5.
Even more interesting, when I summarize an external route with AD 170, it becomes AD 90.

I have two basic questions:
(1) What should I do to observe the AD being set to 5?
(2) Is my expectation so wrong that I expect to see AD set to 5?

Many thanks,




  • The AD of 5 is only used for the discard-route to null0, generated on the device creating the summary. This is the default AD for the discard-route, but can be changed under the rouing process using the command 'summary-metric' (previously the AD was set in the summary-address command itself, but this has changed in later IOS versions). Throughout the rest of the EIGRP network, the route will be seen as a regular EIGRP internal route, which will then have an AD of 90 (by default).

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