Hi Jacques,

From the snippet of config you pasted below:
I see you are not advertising all of your 6 (now 7) prefixes to _both_
upstreams, just 3 to ISP1 and 3 to ISP2.
This will work, yes, but has not really added BGP-functionality. It has the
same effect as statically routed blocks.
What if the trunk to ISP-1 fails?
The 3 prefixes you announce to them are not announced to ISP-2 and will
disappear from the global routing-table.
You should try and announce all of your blocks to all upstreams and then let
AS_PATH (or any other attribute you see fit) do the balancing:

=========
On router 1:
=========
 neighbor Loopback0 remote-as ISP1
 neighbor Loopback0 route-map ISP1-IN in
 neighbor Loopback0 route-map ISP1-OUT out
!
ip as-path access-list 2 permit ^$
!
ip prefix-list prepend seq 10 permit network1/24 le 32
ip prefix-list prepend seq 15 permit network2/24 le 32
ip prefix-list prepend seq 20 permit network3/24 le 32
!
ip prefix-list no-prepend seq 10 permit network4/24 le 32
ip prefix-list no-prepend seq 15 permit network5/24 le 32
ip prefix-list no-prepend seq 20 permit network6/24 le 32
!
route-map ISP1-OUT permit 20
 match ip address prefix-list prepend
 match as-path 2
 set as-path prepend MyAS MyAS
!
route-map ISP1-OUT permit 30
match ip address prefix-list no-prepend
match as-path 2

=========
On router2:
=========
 neighbor Loopback0 remote-as ISP2
 neighbor Loopback0 route-map ISP2-IN in
 neighbor Loopback0 route-map ISP2-OUT out
!
ip as-path access-list 2 permit ^$
!
ip prefix-list prepend seq 10 permit network4/24 le 32
ip prefix-list prepend seq 15 permit network5/24 le 32
ip prefix-list prepend seq 20 permit network6/24 le 32
!
ip prefix-list no-prepend seq 10 permit network1/24 le 32
ip prefix-list no-prepend seq 15 permit network2/24 le 32
ip prefix-list no-prepend seq 20 permit network3/24 le 32

!
route-map ISP2-OUT permit 20
 match ip address prefix-list prepend
 match as-path 2
 set as-path prepend MyAS MyAS
!
route-map ISP2-OUT permit 30
match address prefix-list no-prepend
match as-path 2

As for the 7-nd block: route it however you want..

Cheers,
Jeffrey Belles



----- Original Message -----
From: "Jacques VUVANT" <jacques.vuvant@...>
To: <isp-bgp@isp-bgp.com>
Sent: Friday, July 18, 2003 3:40 AM
Subject: [isp-bgp] Advertising in BGP


> Hello all
>
> I have a network constituted with 2 routers (R1 and R2)connected on
> iBGP, and each router is connected in eBGP to ISPs (ISP1 and ISP2). I'm
> trying to manage incoming traffic of routes advertised by my AS with
> prefix and route-map with as-prepend as following and it work well, see
> configuration:
>
> On R1
> =====
> router bgp MyAS
> .....
>  neighbor Loopback0 remote-as ISP1
>  neighbor Loopback0 route-map ISP1-IN in
>  neighbor Loopback0 route-map ISP1-OUT out
> !
> ip as-path access-list 2 permit ^$
> !
> ip prefix-list TO-R2 seq 10 permit network1/24 le 32
> ip prefix-list TO-R2 seq 15 permit network2/24 le 32
> ip prefix-list TO-R2 seq 20 permit network3/24 le 32
> !
> route-map ISP1-OUT permit 20
>  match ip address prefix-list TO-R2
>  match as-path 2
>  set as-path prepend MyAS MyAS
> !
> route-map ISP1-OUT permit 30
>  match as-path 2
>
>
> On R2
> ========
> router bgp MyAS
> .....
>  neighbor Loopback0 remote-as ISP2
>  neighbor Loopback0 route-map ISP2-IN in
>  neighbor Loopback0 route-map ISP2-OUT out
> !
> ip as-path access-list 2 permit ^$
> !
> ip prefix-list TO-R1 seq 10 permit network4/24 le 32
> ip prefix-list TO-R1 seq 15 permit network5/24 le 32
> ip prefix-list TO-R1 seq 20 permit network6/24 le 32
> !
> route-map ISP2-OUT permit 20
>  match ip address prefix-list TO-R1
>  match as-path 2
>  set as-path prepend MyAS MyAS
> !
> route-map ISP2-OUT permit 30
>  match as-path 2
>
> My question is if I add route on both Prefix-list, for example:
>
> On R1:
> ======
> ip prefix-list TO-R2 seq 10 permit network1/24 le 32
> ip prefix-list TO-R2 seq 15 permit network2/24 le 32
> ip prefix-list TO-R2 seq 20 permit network3/24 le 32
>
> On R2:
> ======
> ip prefix-list TO-R1 seq 10 permit network4/24 le 32
> ip prefix-list TO-R1 seq 15 permit network5/24 le 32
> ip prefix-list TO-R1 seq 20 permit network6/24 le 32
> ip prefix-list TO-R2 seq 20 permit network3/24 le 32
>
> What should happen on advertising ?
>
> Thanks for any answer
>
>
> Jacques VUVANT
> Network OPT New-Caledonia
> Phone : +687-267541
> Fax : +687-278444
> Mob : +687-773121
> Mail : Jacques.vuvant@...
>
>
> -----Message d'origine-----
> De : Carl-Henrik Landgren [mailto:landgren@...
> Envoyé : mercredi 16 juillet 2003 23:19
> À : isp-bgp@isp-bgp.com
> Cc : isp-bgp@isp-bgp.com
> Objet : [isp-bgp] RE: Sample BGP Config
>
> Depending on what link you want the traffic to take, it's pretty
> simple....
>
> Just make the link you don't want the outbound traffic to pass with a
> longer AS-PATH, just add your own AS to the AS-SEQUENCE several times to
> make it long enough.
>
> Or, you can filter with LOCAL-PREF for the prefixes you want the
> outbound-traffic to exit your AS.
>
> The rest i assume you know how to configure yourself.
>
> /Carl
>
>
>
> ------- Ursprungligt brev -------
> Från: chris@...
> Datum: Tue, 15 Jul 2003 14:58:48 -0700
>
> Michael,
>
> Thanks for the response.  The example I read was "Load Sharing when
> Multihomed to Two ISPs via Multiple Local Routers"
>
> The outbound traffic policy in this example limits traffic to one of the
> two providers unless there is a failure.
>
> The outbound traffic policy is as follows:
> Traffic destined to AS 300 goes via the R1 - ISP(A) link.
> Traffic destined to AS 400 goes via the R2 - ISP(B) link.
> All other traffic should prefer default route 0.0.0.0 via the R1 -
> ISP(A) link.
> If the R1 - ISP(A) link fails, all traffic should go via the R2 - ISP(B)
> link.
>
> I'd like to have outbound traffic take the shortest path if both ISP's
> are up and fail over to the other ISP if one ISP link fails.
>
>
> Christopher J. Wolff, VP CIO
> Broadband Laboratories, Inc.
> http://www.bblabs.com
>
> -----Original Message-----
> From: Michael Weinstock [mailto:MWeinstock@...> Sent: Tuesday, July 15, 2003 2:50 PM
> To: isp-bgp@isp-bgp.com
> Subject: [isp-bgp] RE: Sample BGP Config
>
> Hello,
>
> You didnt like it? Perhaps specify what you didnt like... As the answer
> will be based on Cisco's docs.
>
> -----Original Message-----
> From: Christopher J. Wolff [mailto:chris@...> Sent: Wednesday, 16 July 2003 9:47 a.m.
> To: isp-bgp@isp-bgp.com
> Subject: [isp-bgp] Sample BGP Config
>
>
> Hello,
>
> I'm looking for a couple of sample cisco configs that illustrate two
> multihomed routers connected by an IGP session.  For example;
>
> Router 1----------Isp 1
> |
> |
> IGP
> |
> |
> Router 2----------Isp 2
>
> I read the Cisco scenarios for multihomed networks documents but I
> didn't like what I read.  Thank you in advance.
>
> C.J. Wolff, VP CIO
> Broadband Laboratories, Inc.
> http://www.bblabs.com
>
>
>
>
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>
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>
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>

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[isp-bgp] RE : Re: Advertising in BGP, Jacques VUVANT

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[isp-bgp] Advertising in BGP, Jacques VUVANT