PBR needing to hit the cpu?

Sun Sep 18 06:40:20 UTC 2005

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