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Re: Cisco filter question

  • From: Paul A. Bradford
  • Date: Fri Aug 22 13:18:35 2003

Geo,
   OK Time for me to get coffee....  I missed the "not stop".

it might not stop a packet if the route-map isn't applied to the
interface.....

Pablo

On Fri, 2003-08-22 at 12:58, Paul A. Bradford wrote:
> Geo,
>    Not sure if I want to answer. is this OT for NANOG?  :)
> 
>    the key is:
> 
> IP: Total Length = 92 (0x5C)
> 
> normal ICMP packets are not 92 bytes in length.... our friend Nachi does
> use 92 byte packets.
> 
> BTW: good luck trying the route-map on 2948G-L3s...  ;)
> 
> Thanks,
> Paul
> 
> 
> On Fri, 2003-08-22 at 12:55, Jack Bates wrote:
> > Scott McGrath wrote:
> > 
> > > 
> > > Geo,
> > > 
> > > Look at your set interface Null0 command the rest is correct
> > > you want to set the next hop to be Null0.  How to do this is left as an 
> > > exercise for the reader.
> > > 
> > 
> > Interface Null0 works fine. Here's a quick check.
> > 
> > Inbound (from peers) policy matches
> > route-map nachi-worm, permit, sequence 10
> >    Match clauses:
> >      ip address (access-lists): 199
> >      length 92 92
> >    Set clauses:
> >      interface Null0
> >    Policy routing matches: 10921 packets, 1048416 bytes
> > 
> > Outbound (to internal network) accesslist matches
> > Extended IP access list 181
> >      deny tcp any any eq 135 (1994 matches)
> >      permit icmp any any echo (757 matches)
> >      permit icmp any any echo-reply (381 matches)
> >      permit ip any any (381370 matches)
> > 
> > I cleared 181 first, then cleared route-map counters. I then checked 
> > route-map counters first before checking access-list counters. This 
> > means the access-list has more time to accrue maches yet it is 
> > considerably smaller. The checks were a matter of seconds. I'd say the 
> > policy is working. The echo/echo-reply could easily be everyday pings 
> > which are up abit due to various networks having performance issues.
> > 
> > IOS Versioning can sometimes have issues. There's also the question of 
> > if the packet came in the inbound interface that had the policy applied.
> > 
> > -Jack
-- 
Paul A Bradford
Senior Network Engineer
Adelphia Cable Communications
814-274-1353






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