From: Shaikh, Nasir (Nasir.Shaikh@atosorigin.com)
Date: Wed Mar 09 2005 - 08:36:37 GMT-3
Thanks Farid, I guess bgp is the only feasible option.
greetz
Nasir
-----Original Message-----
From: farid khwaja [mailto:faridkhwaja@yahoo.com]
Sent: woensdag 9 maart 2005 10:38
To: Shaikh, Nasir
Cc: ccielab@groupstudy.com
Subject: Re: redundant network with shadow links
If you want to use Multilink ppp then u can club the
two links on R1 to destination A into a Multilink.
Using the command ppp
multilink links minimum 2 mandatory will allow you to
bring down the mlink in case one of the two links goes
down.
You can further make use of IP event dampening to take
care of flapping multilinks.
dampening 30 1 1 255
There are other ways to achieve what you want, but
then we need to go for more flexible routing protocol
such as BGP.
regards
farid
======================================================
If you have concerns using ppp then you can use BGP
for
--- nasir.shaikh@atosorigin.com wrote:
> Hi guys,
> This is NOT something that I have come across in any
> practice lab scenario but am quite curious about the
> possibilities
> Suppose we have the following situation:
>
>
> 12 34 ss ss
> \\ // \\ //
> __\\_//__ __\\_//__
> |___r1___|----|__r2___|
> | |
> ___ |____ ___|____
> |___s1___|----|__s2___|
>
> R1 has WAN connections to 2 remote locations. Links
> 1 and 2 do load balancing (per-destination) to
> destination A and links 2 and 3 to destination B.
> R2 has shadow links to the same destinations. Under
> normal circumstances, the shadow links are not used.
> Let's say link 1 on R1 goes down thus reducing the
> bandwidth to dest A by 50%. In such a situation I
> want the traffic to use only the shadow links on r2
> for destination A. The "bundle" of lins 1 and 2
> should not be used at all. For destination B the
> links on R1 should continue to be used.
> All devices have layer 3 connectivity. The S1 and S2
> are layer 3 capabale switches (e.g. 3550 EMI,). R1
> and R2 are say 7200 routers. EIGRP is used on all
> devices. The remote site has a similar setup.
>
> Is there a technology or feature that can be used to
> make the network consider the bundle (1 and 2) as
> unusable and switch over to the shadow links? Using
> PPP reliable-link is an option, I think but would
> give a lot of overhead if the WAN links are ATM
> pvcs.
>
> Any ideas?
>
> Nasir
>
>
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