Tuesday, May 11, 2010

Sometimes Answers will be a Question !!!! Route Precedence

Recently I got a call from one of my followers, asking if we have three routes

10.10.10.0/24 via bgp
10.10.10.0/24 via ospf
10.10.0.0/16 via eigrp

which route will take for 10.10.10.1??

Now the basic funda is,

Route selection precedence is as follows

1. Most Specific route
2. AD value
3. Metric


Now here most specific routes are

10.10.10.0/24 via bgp
10.10.10.0/24 via ospf

Now AD value will come in the picture as tie breaker....

Take a look at the following Table for AD values

Default Administrative Distances
Connected 0
Static 1
eBGP 20
EIGRP (internal) 90
IGRP 100
OSPF 110
IS-IS 115
RIP 120
EIGRP (external) 170
iBGP 200
EIGRP summary route 5


Now the Answer is a question, Which BGP route was that, EBGP or IBGP??

If it is IBGP (AD value: 200), OSPF routes will get precedence…. Else it gonna take BGP routes (AD Value: 20)

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.