We could ask Cisco and Juniper to add a way of 'artificially' remove networks from the CEF table (with an ACL or so). That way, even with loose-RPF, the packet will be dropped based on source-address at the ingress without consuming CPU.
Or maybe such a feature already exist
Andr�
Andre,
Actually it already exists. But to do it, you need
to ensure you have loose-RPF checking enabled and null-route
the network you want the data dropped for. Since a null-route
is considered by loose-RPF checking as a "bad" route, it will
drop the data for you.
thanks,
charles
We could ask Cisco and Juniper to add a way of 'artificially' remove
networks from the CEF table (with an ACL or so). That way, even with
loose-RPF, the packet will be dropped based on source-address at the
ingress without consuming CPU.
Keep in mind that this functionality would still be held to the same set
of restrictions as uRPF... and you CAN accomplish this with a blackhole
setup on your network. By blackholing source prefixes you COULD get this
same effect.
Or maybe such a feature already exist
it kind of does... though with some real routing goo, not via an acl.
With Juniper gear there is no performance difference between what you propose
and an ACL, both run at wire rate. So implementing "CPU saving measures" is pointless
waste of time.
Pete
We could ask Cisco and Juniper to add a way of 'artificially' remove networks from the CEF table (with an ACL or so). That way,
even with loose-RPF, the packet will be dropped based on source-address at the ingress without consuming CPU.
Or maybe such a feature already exist
Andr�>Looking for advice.
>
>I am sorry if this was discussed before, but I cannot seem to find this.
>I want to use source routing as a way to stop a DoS rather than use access-lists.
>
>In other words, lets say I know the source IP (range of IPs) of an attack and they do not change.
>
>If the destination stays the same I can easily null route the destination, but what if the destination constantly changes. So I
have to work based on the source IP.
>
>Depending on the router and the code, if I implement an access-list then the CPU utilization shoots through the roof.
>What I would like to try and do is use source routing to route that traffic to null. I figured it would be easier on the router
than an access-list.