nanog mailing list archives

Re: Code Red


From: "Stephen J. Wilcox" <steve () opaltelecom co uk>
Date: Fri, 20 Jul 2001 17:03:18 +0100 (BST)



you said you had large numbers of unused IP addresses.

split the block down into manageable chunks, send the chunks to the
relevant interfaces and route the whole netblock to null

your used ips go out to their appropriate networks and the unused ones
having nowhere to go get sent to null.

So: No ARPs to spare netblocks!


by splitting it into subnets you will also reduce the amuont of broadcast
traffic on the network, (each bad ip will generate several broadcast arp
packets)

And: Better network performance, improved bandwidth!

Steve


On Fri, 20 Jul 2001, Larry Sheldon wrote:

Jeff Ogden wrote:
is causing network problems due to heavy ARP loads when the local
site routers ARP for what turn out to be unused IP addresses.  This
is an issue when there are large blocks of IP addresses behind a
router. It is less of a problem when there is a relatively small
number of IP addresses behind a router (say one class C worth). Are
others seeing these sorts of problems?  What strategies are there for
dealing with this?

Use smaller subnets (possibly vlans etc) !

Steve

I don't clearly see how this will help.




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