RE: the value of tags

From: Scott Morris (smorris@ipexpert.com)
Date: Wed Sep 19 2007 - 11:54:40 ART


You can scale the tags as much or as little as you want. It's simply an
exercise in logic (and typing!). :)

Whether you have multiple points of redistribution to the same routing
protocol and wanto to use the same tag or different tags is up to you.

You may have 100 = RIP, 200 = OSPF as an example. In a larger concept, you
could have tag 101 = RIP from R1, 102 = RIP from R2, 204 = OSPF from R4,
etc.

The goal of it all is a simpler/scalable way to pick exactly what goes where
and watching to be sure you don't have loops.

Sometimes it'll make your head hurt, but should scale just fine.

 
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE-M
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-ER
VP - Technical Training - IPexpert, Inc.
IPexpert Sr. Technical Instructor
 
A Cisco Learning Partner - We Accept Learning Credits!
 
smorris@ipexpert.com
 
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-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Joe
Dewberry
Sent: Wednesday, September 19, 2007 9:33 AM
To: ccielab@groupstudy.com
Subject: the value of tags

Hi,

I have been tossing around quite a few redistribution schemes and found the
"tagging" method. See a quick snapshot below for RIP & OSPF

!
route-map OSPF-->RIP deny 10
 description --- route originated in RIP --- match tag 1 !
route-map OSPF-->RIP deny 20
 description --- route was in EIGRP & RIP --- match tag 11 !
route-map OSPF-->RIP deny 30
 description --- route was in OSPF & RIP --- match tag 101 !
route-map OSPF-->RIP permit 40
 description --- route originated in EIGRP, add OSPF --- match tag 10 set
tag 110 !
route-map OSPF-->RIP permit 50
 description --- route originated in OSPF --- set tag 100 !
route-map RIP-->OSPF deny 10
 description --- route originated in OSPF --- match tag 100 !
route-map RIP-->OSPF deny 20
 description --- route was in RIP & OSPF --- match tag 101 !
route-map RIP-->OSPF deny 30
 description --- route was in EIGRP & OSPF --- match tag 110 !
route-map RIP-->OSPF permit 40
 description --- route originated in EIGRP, add RIP --- match tag 10 set
tag 11 !
route-map RIP-->OSPF permit 50
 description --- route originated in RIP --- set tag 1

the values of the tags being

RIP == 1
EIGRP == 10
OSPF == 100

I see the value here as it can do a good job of eliminating unwanted
routes...has anyone come across a scenario (NetMasterClass) where this would
not work/scale?

--
Joe Dewberry


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