Using Policy Routing to stop DoS attacks

Tue Mar 25 14:58:39 UTC 2003

At 09:21 AM 3/25/2003 -0500, Haesu wrote:

>I dunno how you want to implement this; but as far as I know, the way most
>people generally do policy routing on cisco thru routemap is they define
>the source IP's via access-list... Does that make a huge difference than
>regular access lists? I dunno...
Well yes, It seems that an IP deny is more process intensive than an IP 
permit. I do not claim to know why. I have just seen it myself.

Anyway depending on the attack with large numbers of packets sometimes the 
CPU is so high you can get knocked off the router.
I wanted to see if policy routing is less taxing on the router.

With the access-list for a policy route map you have a access-list permit, 
so I figured it might be less taxing.

>Which Cisco router ? IOS ?
>  HW/SW/CEF/netflow/<whatver>  "IP switching"  ?
While I have had this problem on different routers the ones I constantly 
have it on are Cisco Cat 5000s with RSMs(RSP4). I have tried different 
codes, I am currently at 12.04. But it's not a code issue. It's just a 
limitation of the router. I just need something less taxing on the router.

I just need to know if anyone has already done this.