From: Bhisham Bajaj (bhishambajaj@xxxxxxxxx)
Date: Mon Jun 17 2002 - 13:38:11 GMT-3
Interesting question, how do u come up with such
questions
But a very good way of playing with routing protocols
to understand how it works
Your requriment is that R1 must advertise 2 networks
to R2 that is in a different AS and R2 must only
install one out of them without doing any thing on R2
Ok so I can only do some thing on R1 and I cannot
filter
So I must do some thing to one of the network so that
r2 does not install it
If I prepend a As path in one of the network that is
being advertised from R1 to R2 with the same AS of R2
then R2 will not install any route that has its As
number in the AS path
BB
--- Abidin Kahraman <kahramana@superonline.net> wrote:
> Umit,
>
> You can change your ip range`s next-hops with
> route-maps..Shown below config
> is solution for your question.
>
> R1
> -------------
>
> router bgp 1
> network 30.30.30.0 mask 255.255.255.0
> network 30.30.40.0 mask 255.255.255.0
> neighbor 5.5.5.6 remote-as 2
> neighbor 5.5.5.6 route-map Myroutemap out
> no auto-summary
> !
> ip route 30.30.30.0 255.255.255.0 Null0
> ip route 30.30.40.0 255.255.255.0 Null0
> !
> access-list 10 permit 30.30.40.0 0.0.0.255
> route-map Myroutemap permit 10
> match ip address 10
> set ip next-hop 1.1.1.1
> !
> route-map Myroutemap permit 20
>
> R2
> ----------
>
> router bgp 2
> neighbor 5.5.5.5 remote-as 1
> no auto-summary
> !
>
>
>
> Abidin.
>
>
>
> -----Original Message-----
> From: \mit A~kan (TK-Network Gvz|mleri)
> [mailto:umit.askan@probil.com.tr]
> Sent: Monday, June 17, 2002 4:57 PM
> To: 'kym blair'
> Cc: Ccie (E-mail)
> Subject: RE: BGP no-filter (correction)
>
> don't forget you must see the routes between the
> advertised ones.
> That means you can't use any Filtering
>
> -----Original Message-----
> From: kym blair [mailto:kymblair@hotmail.com]
> Sent: Monday, June 17, 2002 16:41
> To: kymblair@hotmail.com; umit.askan@probil.com.tr;
> ccielab@groupstudy.com
> Subject: Re: BGP no-filter (correction)
>
>
> Oops, Solution 3 had an error. Should be:
>
> SOLUTION 3 (lets all routes except .20 go):
>
> R1
>
> access-list 12 deny 10.10.20.0 0.0.0.255
>
> route-map BLOCK30 permit 10
> match ip address 12
> route-map BLOCK30 permit 20
>
> bgp 4
> neighbor 10.10.30.2 route-map BLOCK30 out
>
>
>
> -------or-----------
>
> SOLUTION 3 (lets all routes except .20 go):
>
> R1
>
> access-list 12 permit 10.10.20.0 0.0.0.255
>
> route-map BLOCK30 deny 10
> match ip address 12
> route-map BLOCK30 permit 20
>
> bgp 4
> neighbor 10.10.30.2 route-map BLOCK30 out
>
>
>
>
> >From: "kym blair" <kymblair@hotmail.com>
> >Reply-To: "kym blair" <kymblair@hotmail.com>
> >To: umit.askan@probil.com.tr,
> ccielab@groupstudy.com
> >Subject: Re: BGP no-filter
> >Date: Mon, 17 Jun 2002 13:22:55 +0000
> >
> >SOLUTION 1 (only permits route 10.10.10.0 to be
> advertised):
> >
> >R1
> >
> >access-list 12 permit 10.10.10.0 0.0.0.255
> >
> >route-map LET10GO permit 10
> >match ip addr 12
> >
> >bgp 4
> > neighbor 10.10.30.2 route-map LET10GO out
> >
> >--------------------------------------------------
> >
> >SOLUTION 2 (same):
> >
> >R1
> >
> >access-list 12 permit 10.10.10.0 0.0.0.255
> >
> >bgp 4
> > neighbor 10.10.30.2 distribute-list 12 out
> >
> >---------------------------------------------------
> >SOLUTION 3 (lets all routes except .20 go):
> >
> >R1
> >
> >access-list 12 deny 10.10.20.0 0.0.0.255
> >
> >route-map BLOCK30 deny 10
> > match ip address 12
> >route-map BLOCK30 permit 20
> >
> >bgp 4
> > neighbor 10.10.30.2 route-map BLOCK30 out
> >
> >--------------------------------------------------
> >SOLUTION 4 (filters inbound; not as effective):
> >
> >R2
> >
> >access-list 12 permit 10.10.10.0 0.0.0.255
> >
> >route-map LET10IN permit 10
> > match ip address 12
> >
> >bgp 4
> > neighbor 10.10.30.1 route-map LET10IN in
> >
> >
> >
> >HTH, Kym
>
>--------------------------------------------------------
> >
> >
> >>From: \mit A~kan (TK-Network Gvz|mleri)
> <umit.askan@probil.com.tr>
> >>Reply-To: \mit A~kan (TK-Network Gvz|mleri)
> <umit.askan@probil.com.tr>
> >>To: "Ccie (E-mail)" <ccielab@groupstudy.com>
> >>Subject: BGP no-filter
> >>Date: Mon, 17 Jun 2002 15:59:50 +0300
> >>
> >>Hi,
> >>
> >>I have got a problem like that :
> >>
> >>network 10.10.10.0 R1-------EBGP--------R2
> >>network 10.10.20.0
> >>
> >>I want to see only 10.10.10.0 at R2 bgp table. But
> if you look to the
> >>R1's advertised routes to R2, you will see
> 10.10.10.0 and 10.10.20.0.
> >>You can't do anything on R2 for that routes.
> >>
> >>Best Regards
> >>
> >>\mit A~kan
> >>Consulting Network Engineer
> >>CCNP, CCDP, CCNP-Security, CCNP-Voice Access
> >>
> >> > Probil Bilgi Islem Destek ve Danismanlik San.
> ve Tic. A.S.
> >>Eski Buyukdere Caddesi Dilaver Sokak No.4
> >>Otosanayi 4. Levent 80660 Istanbul
> >>
> >>Tel: +90 (212) 317 61 00 (219)
> >>Direkt : +90 (212) 317 62 19
> >>Faks: +90 (212) 325 55 15
> >>E-Mail: umit.askan@probil.com.tr
> >>Web: www.probil.com.tr
>
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