Packets from net 10 (no, not the lyrics)

Kenneth E. Gray kegray at
Tue Sep 23 17:45:28 UTC 1997

And that would be process switching to Null0, I believe.

At 08:22 AM 9/23/97 -0700, Kevin Oberman wrote:
>> Date: Tue, 23 Sep 1997 10:45:19 -0400
>> From: "Randall S. Benn" <rbenn at>
>> I think you'll find that your router's CPU will be happier if you just dump
>> the 1918 networks to the bit bucket on your border routers with a static
>> route via interface Null0:
>>    ip route null0
>>    ip route null0
>>    etc.
>> Considering resource utilization on the router, it is cheaper to do a
>> routing table look-up than it is to do ACLs.  Also, when you're doing
>> outbound filtering on the router, you have to do a routing table lookup
>> first before you can do outbound filtering.  Save a step and just do the
>> routing table lookup.
>I don't think so. The static routes will require processing every
>packet destined for the and nets, but you will
>still have the bad route. The CPU will have to deal with any traffic
>for and any interior routers will forward packets since you
>have a route.
>On the other hand, a filter on the BGP session will block the route
>from being accepted and only require CPU action once...when it is
>announced. You have no route to these nets and can't propagate the
>routes since you don't have them.
>Andrew clearly has the correct approach.
>R. Kevin Oberman, Network Engineer
>Energy Sciences Network (ESnet)
>Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
>E-mail: oberman at			Phone: +1 510 486-8634
Ken Gray                                                 ||        ||
ISP Systems Engineer                                     ||        ||
Reston, Virginia   USA                                  ||||      ||||
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