RE: routing sequence

Thank you very much Iain, Scott and all,

I really need to brush up this...I am confused at times. 

Thanks much!

-----Original Message-----
From: nobodygroupstudy.com [mailto:nobodygroupstudy.com] On Behalf
Of
Scott Morris
Sent: Tuesday, July 15, 2008 6:58 PM
To: ciscogroupstudy.com
Subject: RE: routing sequence [7:131928]

PBR is actually done first.  This technically AVOIDS the
routing process
(manual routing).

Otherwise, most-specific matching is done on your route. 
(longest prefix
match)

If you have more than one protocol (static or dynamic) that
gives the same
prefix, administrative distance (AD) is used to select the
best path.  If
different AD values, only one will appear in "show ip
route"

So you can play some interesting tricks with that.  Namely
you can have a
connected interface (which logically trumps everything)
configured as  "ip
address 172.1.1.1 255.255.255.0" and then you have a
route (static or
dynamic doesn't matter) for 172.1.1.0/25 (255.255.255.128)
pointing to
another router.  This is a more specific match.

Now, if you ping 172.1.1.1 that's your local interface IP. 
It will go
locally.

If you ping 172.1.1.2, it will go to a remote router because
172.1.1.0/25 is
more specific than 172.1.1.0/24.

If you ping 172.1.1.150, it will go to the directly
connected interface.

Kinda messes with your head sometimes!  But the bottom line
is most specific
match wins!

HTH,


Scott Morris, CCIE4 #4713, JNCIE-M #153, JNCIS-ER, CISSP, et
al.
CCSI/JNCI-M/JNCI-ER
Senior CCIE Instructor

smorrisinternetworkexpert.com

 

Internetwork Expert, Inc.
http://www.Internet
workExpert.com
Toll Free: 877-224-8987
Outside US: 775-826-4344
Online Community: http://www.IEOC.com
CCIE Blog: http://blog.intern
etworkexpert.com


Knowledge is power. 
Power corrupts. 
Study hard and be Eeeeviiiil......
 

-----Original Message-----
From: nobodygroupstudy.com [mailto:nobodygroupstudy.com] On Behalf
Of Paul
Yeo
Sent: Tuesday, July 15, 2008 2:00 AM
To: ciscogroupstudy.com
Subject: routing sequence [7:131928]

Hi folks,

Am I understood this correctly, the routing will process in
this way:

1) very specific static route - e.g. 172.1.1.0
255.255.255.0
2) general static route --- e.g. 172.1.0.0 255.255.0.0
3) routing protocol route - e.g. eigrp
4) pbr

I have a remote router configured with a very specific route
than my central
router, it seems that the router actually choose the remote
router to route
to the destination.

Tx,




Message Posted at:
http://www.groupstudy.com/form/read.php?f=7
&i=131949&t=131928
--------------------------------------------------
FAQ, list archives, and subscription info: http://www.
groupstudy.com/list/cisco.html