Re: PBR needing to hit the cpu?

["Fergie (Paul Ferguson)" <fergdawg () netzero net>]

What I think we're talking about here is not really "policy-
based routing" but "policy-based forwarding", right?

If so, then any nin-FIFO scheme would have to to be kicked up
to the CPU, right?

- ferg

ps. I heard you left Cisco again. ;-)



-- Tony Li <tony.li () tony li> wrote:

On Sep 17, 2005, at 8:57 PM, David Hubbard wrote:
> Just curious, do most vendors' hardware need to hit the
> cpu when doing policy-based routing?  I found one of my
> border routers' cpu's on the bad end of a DDoS but once
> I turned off a not necessarily required setup to force
> some outbound traffic to take a specific outbound link
> via PBR, the DDoS traffic was no longer an issue.  It was
> only about 200 Mbit so I hadn't expected it to be an issue
> but apparently it was; I was surprised when support told
> me the PBR was making traffic hit the cpu.


That's not at all surprising.  PBR would be pretty hard to push into  
a hardware forwarding path.
Not impossible, but certainly challenging.

Tony