From: Darren Johnson (dazza_johnson@yahoo.co.uk)
Date: Fri Jan 11 2008 - 14:20:39 ARST
Ok, no-one answered this one so Ill pick it up :-)
You are right, EIGRP makes life much simpler with the EIGRP external AD 170.
Here is how it works...
Assume the two routers doing redistribution are R1 and R2 both running OSPF
and EIGRP.
OSPF native routes (routes learned via OSPF) get redistributed into EIGRP by
R1. As EIGRP external routes, they have an AD of 170. R2 recieves the route
and has a decision to make - use the OSPF route or EIGRP route. OSPF AD is
110 so it uses that route (versus AD 170). Same thing works with R2 doing
the redistribution.
On the other hand, R1 ones redistributes the EIGRP native routes into OSPF.
R2 recievies these routes via OSPF and has a decision to make - use the
EIGRP route or OSPF? Internal EIGRP AD is 90 and OSPF is 110 - so EIGRP
native routes are installed as EIGRP.
Sumamry, in this scenario you will always have optimum routing - thanks to
EIGRP external AD. Now, RIP into OSPF and vice-versa, is a little
trickier.......!
Does that makes sense?
Dazzler
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Monica Belluci
Sent: 10 January 2008 05:56
To: Cisco certification
Subject: Mutual Redistribution
Hi Guys,
If I do mutual redistribution on two ASBR connecting with same Autinomuos
systems First (EIGRP) and Second (OSPF) .
As I can understand EIGRP will automatically make it 170 AD for external
routes so optimal path will be selected .
please give comments..
thanks
Nalini Roy
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