Re: Tag BGP external routes?

From: Mirco Orlandi <mirco.orlandi_at_gmail.com>
Date: Mon, 22 Mar 2010 17:25:26 +0100

Ivan, by your show on SW2 I see you are using "tag 200" inside
redistribution statement.
Result should be:
- change tag to 999 for routes with tag 254
- set tag 200 to others

It works fine on my lab.

What do you mean by "I know that my EIGRP neighbor is in AS 253"?
You have ospf 1, eigrp AS100, and a remote bgp peer with AS254. Is AS253 the
local BGP AS of SW2 eigrp neighbor?

-mirco.

On Mon, Mar 22, 2010 at 4:40 PM, Ivan Hrvatska <ivanzghr_at_gmail.com> wrote:

> Well, let's say that my EIGRP neighbor, which is also BGP router,
> recives some prefixes via eBGP session and redistribute them into
> EIGRP. My router (SW2) recives that prefixes via EIGRP and EIGRP has
> originator's AS number as route tag:
>
> SW2#sh ip ro 99.99.1.0
> Routing entry for 99.99.1.0/24
> Known via "eigrp 100", distance 170, metric 2560000512
> Tag 254, type external
> Redistributing via ospf 1, eigrp 100
> Advertised by ospf 1 subnets tag 200 route-map TAG
> Last update from 9.9.33.254 on Vlan33, 00:04:02 ago
> Routing Descriptor Blocks:
> * 9.9.33.254, from 9.9.33.254, 00:04:02 ago, via Vlan33
> Route metric is 2560000512, traffic share count is 1
> Total delay is 20 microseconds, minimum bandwidth is 1 Kbit
> Reliability 1/255, minimum MTU 1 bytes
> Loading 1/255, Hops 1
> Route tag 254
>
> If I use that tag 254 in my route-map like this, because I know that
> my EIGRP neighbor is in AS 253:
>
> !
> route-map TAG permit 10
> match tag 254
> set tag 999
> !
> route-map TAG permit 90
> !
>
> That prefixes go into OSPF without changed tag ??!! set tag 999 didn't
> change tag. Why?
> If I put tag command under redistribute command then all prefixes will
> be tagged with 999.
> Right?
>
> On Mon, Mar 22, 2010 at 3:50 PM, Mirco Orlandi <mirco.orlandi_at_gmail.com>
> wrote:
> > Hi Ivan,
> > using "tag" inside redistribution statement, you are setting tag 999 to
> all
> > routes you are redistributing.
> >
> > To match the task requirement, you have to set tag 999 only to external
> > eigrp routes
> > On R1:
> >
> > route-map set-tag permit 10
> > match route-type external
> > set tag 999
> >
> > route-map set-tag permit 20
> >
> > router ospf 1
> > redistribute eigrp 1 subnets route-map set-tag
> >
> >
> >
> > but..., if you prefere, you can set tag 999 inside statement and override
> > the tag for non-external routers:
> >
> > route-map set-tag permit 10
> > match route-type external
> >
> > route-map set-tag permit 20
> > set tag 1
> >
> > router ospf 1
> > redistribute eigrp 1 subnets tag 999 route-map set-tag
> >
> >
> > I labbed it with Adv.IP.Svcs 12.4(15)T8
> > I think first solution is more common, and clear.
> >
> > -mirco.
> >
> > On Mon, Mar 22, 2010 at 2:33 PM, Ivan Hrvatska <ivanzghr_at_gmail.com>
> wrote:
> >>
> >> Tagging eBGP prefixes. Hmm...I see why are you confused. I'm also
> >> confused. Cause when you redistribute BGP into EIGRP those prefixes
> >> are external to EIGRP. After that you redistribute them into OSPF.
> >> During that redistribution they will be tagged using match route-type
> >> external no matter what protocol originates that prefixes...
> >>
> >> Well, let's just say that task is "tag all external BGP prefixes with
> >> tag 999". ?
> >>
> >> On Mon, Mar 22, 2010 at 1:26 PM, Marc La Porte <
> marc.a.laporte_at_gmail.com>
> >> wrote:
> >> > Other question: do you mean tagging eBGP prefixes? Or prefixes which
> >> > were
> >> > redistributed into BGP?
> >> >
> >> > On Mon, Mar 22, 2010 at 13:04, Ivan Hrvatska <ivanzghr_at_gmail.com>
> wrote:
> >> >>
> >> >> How do you tag external BGP prefixes? Let's say you have two routers
> >> >> in EIGRP domain. One router (R2) runs EIGRP and BGP with some peers.
> >> >> Other router runs EIGRP and it is also ASBR OSPF router (R1). On R1
> >> >> you redistribute EIGRP into OSPF and during redistribution you have
> to
> >> >> tag BGP external routes with some tag. Is this enough:
> >> >>
> >> >> route-map MAP per 10
> >> >> match route-type external
> >> >>
> >> >> route-map MAP per 100
> >> >>
> >> >> router ospf 1
> >> >> redistribute eigrp 1 subnets tag 999 route-map MAP
> >> >>
> >> >> ??
> >> >>
> >> >>
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> >> >>
> >> >>
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Received on Mon Mar 22 2010 - 17:25:26 ART

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