[c-nsp] BGP Memory on a 6500

[Mattias Eliasson]

My .02,
Could you not have a neighbour statement that detailed peers that where 
prefered to be shutdown when memory is low?
So, you would not get CEF shutdowns etc etc.

Default would be "memory-shortage-shutdown never" and opt would be 
"memory-shortage-shutdown order X" where x is a number detailing which 
peer to be shutdown in which order.

// Wyatt Mattias Eliasson


> Date: Wed, 4 Oct 2006 01:23:38 -0400
> From: Richard A Steenbegen <ras at e-gerbil.net>
> Subject: Re: [c-nsp] BGP memory on a 6500
> To: Tony Li <tli at tropos.com>
> Cc: "'Robert E. Seastrom'" <rs at seastrom.com>,
> 	cisco-nsp at puck.nether.net
> Message-ID: <20061004052338.GI48767 at gerbil.cluepon.net>
> Content-Type: text/plain; charset=us-ascii
>
> On Tue, Oct 03, 2006 at 03:22:53PM -0700, Tony Li wrote:
>>
>>> I think that doesn't make the problem go away, only delays a bit (and
>>> that might be quite small) when you see the problem.  On the plus
>>> side, the current situation means that TAC will know what's going on
>>> as the routing table creeps towards the cutoff point (modulo a
>>> thousand or two routes +/- per provider).  When aggregatability has a
>>> 50% non-deterministic span rather than a 1% non-deterministic span,
>>> things will be rougher for longer.
>>
>> I know some folks that have implemented this and found that it worked
>> VERY well indeed.  Even in centralized portions of a Tier 1 network,
>> this tended to reduce the forwarding table by 20-30% and in edgier
>> situations it was more like 40%.
>>
>> It's well worth it, IMHO, and Cisco should take the opportunity to 
>> port
>> it to IOS.
>
> It works even better if you have a default route. :)
>
> Foundry used such CAM aggregation to keep devices with only 8k 16k or 
> 32k
> cam entries available alive for many years. Of course the simple "don't
> install unnecessary more specifics" solution is non-deterministic, but 
> it
> is trivial to implement, and fairly effective at delaying new hardware
> purchases for a few years (thus explaining why it isn't implemented).
>
> -- 
> Richard A Steenbergen <ras at e-gerbil.net>       
> http://www.e-gerbil.net/ras
> GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 
> 2CBC)
>
>
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