RE: Route redistribution

yeah, but confusion is that route-map matched 890 and 390, but 890 and
390 were not defined any where before in workbook/lab.

If they were how can I look up route tags?

Marcin Zgola
Internetwork Lead
MCSE, CCNA, CCSP, CCIE #18676
Netrix, LLC
http://www.netrixllc.com
Ph. 847-964-5300
Fax.: 847-964-5350

-----Original Message-----
From: Dale Shaw [mailto:dale.shaw_at_gmail.com]
Sent: Sunday, June 07, 2009 9:12 PM
To: Marcin Zgola
Cc: ccielab_at_groupstudy.com
Subject: Re: Route redistribution

Hi Marcin,

On Mon, Jun 8, 2009 at 11:34 AM, Marcin Zgola <MZgola_at_netrixllc.com>
wrote:
> I am confused with "match tag" I know you can tag the routes and stuff
> but what is 890 or 390. Where these values came from? How can I look
> these up?

EIGRP is being redistributed into OSPF on two devices. Device "A" is
setting tag 390, and device "B" is setting tag 890. These values are
completely arbitrary. All routes that are redistributed will be tagged
with those values and propagated through the routing domain.

To ensure that original EIGRP routes redistributed into OSPF are not
redistributed again into EIGRP, a route-map is used on each device to
filter routes learned from the other device.

e.g. device "A" does NOT redistribute routes marked with device B's
tag of 890, and device "B' does not redistribute routes marked with
device A's tag of 390.

This is a loop prevention mechanism.

Anyway, I think the key point for you is that these values are
arbitrary and not based on any pre-defined standard. Not all protocols
have a tag field and therefore not all protocols support tagging. Both
EIGRP and OSPF support 32-bit tag values (0-4294967295).

cheers,
Dale

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Received on Sun Jun 07 2009 - 21:33:10 ART