karl and paul, expostulating

Thu Feb 20 22:27:01 UTC 1997

On Feb 20, 1997, Brett D. Watson wrote:
> 
>   doesn't matter.  in production ios, policy routing (source based 
> routing) is process switched.  there is code in the works to make it 
> fast switched.  but  there is a bug wherein if you do policy routing, 
> and you enable flow or optimum switching on the interface you're 
> doing pr on , it disables the policy routing.
> 
>   that bug may be fixed now but in any case enabling flow switching 
> will *not* speed up policy routing.  and if you're exporting the flow 
> stats, you lose anywhere from 50kpps to 100Kpps of speed.

I have news for you; this isn't policy routing!  We aren't re-writting
any source or destination addresses (which is what policy routing
does).  We're just filtering based on source and destination
parameters (such as address, protocol, port, etc).

Flow switching works very effectively (at least as of IOS 11.1.9).

> 
>   but i'm assuming you aren't doing policy routing in this box nor 
> exporting flow stats?

No, we aren't doing policy routing, but we do have an extended access
list on at least one of our fast ethernet interfaces.  The filtering
works quite well, and flow switching makes the CPU load hit minimal.

Alec

-- 
+------------------------------------+--------------------------------------+
|Alec Peterson - ahp at hilander.com    | Erols Internet Services, INC.        |
|Network Engineer                    | Springfield, VA.                     |
+------------------------------------+--------------------------------------+