Administrative Distance

[rwagner]

The only 2 AD, i know of, that have different internal and external values is BGP and EIGRP.  BGP is super easy to remember because it is 20 and 200, but EIGRP is 90 and 170.

Does anyone know why Cisco selected 90 and 170?  i.e. why not like 90 and 190 or 70 and 170?

[Jon Marshall]

Ryan

Actually EIGRP has 3 ADs to remember -

5 - EIGRP summary route

90 EIGRP internal

170 EIGRP external

as to why those number were chosen, well obviously they fall between ADs for other routing protocols but yes EIGRP external could have been made 190 if they had wanted. I'm not aware of any technical reason for this. Shame Russ White, a Cisco EIGRP expert, isn't on the forums much these days as i'm sure he would have been able to help out.

Jon