Re: [nsp] Maximum-prefix in BGP

From: Philip Smith (pfs@cisco.com)
Date: Thu Jun 20 2002 - 02:10:44 EDT


No, maximum-prefix is intended to provide operators with a warning when the
number of prefixes received from an eBGP neighbour is higher than a preset
limit.

So, for example, if you only expect 20000 prefixes from a neighbour, you
might set maximum-prefix to be 30000. Once the router has received 75% of
this limit (22500 prefixes), it will produce a syslog message saying that
the 75% limit has been reached. Once the number of prefixes has reached the
preset 30000 limit, the eBGP peering will be shutdown to protect the
router, or the network, from this "error". If you use the "warning-only"
option, the peering will not be torn down, and the router will simply carry
on issuing warnings...

To limit the prefixes you are sending to your customer, you'll need to use
prefix-list or as-path filters. And ofcourse, decide which 20k prefixes
your customer wants/needs...

philip

--

At 13:47 20/06/2002 +0800, Ysmael B. Tan wrote: >Hi, > >Just want to ask everybody regarding the Maximum-prefix command in BGP. >I haven't tried on our routers, I have understand the concept but will >this effectively limit the number of prefixes received by the neighbor router?? > > >neighbor maximum-prefix XXXX > >neighbor maximum-prefix XXXX warning-only > > >I have a customer who is asking partial routes from the internet (10k to >20k only) will this command do the trick? > > >Thanks for all your reply, > >Ysmael Tan >



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