nanog mailing list archives
Re: cpu needed to NAT 45mbs
From: Deepak Jain <deepak () ai net>
Date: Thu, 08 Nov 2007 18:10:29 -0500
A second CPU or core will help tremendously. We used to use single-CPU boxes for this and we noticed that traffic sometimes stalls when the machine has to do some task other than NATting, such as expiring idle flows. Having a second CPU or core will help keep latency much more uniform. We have a few dual 3.2Ghz Xeon boxes (not the ones based on Core, the older ones) that NAT/FW across two GE interfaces. They do quite well up to about 300Mb/s, then we start to see issues. We believe the issues are due to overloading the NB-SB link. A more modern mobo probably wouldn't have this problem.
Since we are talking about PC Routers... 300Mb/s is a limitation we've seen before... especially related to Interrupts overwhelming the system. Modern ethernet cards (non-interrupt based) and a modern OS with support for all of their offloading and zero-copy functions will improve this greatly.
Current FreeBSD is signficantly faster than current Linux implementations for this kind of work.
But (as I told the OP privately) 45mb/s is a joke and doesn't really need anything more than a 400mhz P-II with two Intel EtherExpress cards and 1GB of RAM. Even for 4,000 downstream connections. A few $200-$300 L3 switches can do this just as well.
Deepak Jain AiNET
Current thread:
- cpu needed to NAT 45mbs Carl Karsten (Nov 08)
- RE: cpu needed to NAT 45mbs Darden, Patrick S. (Nov 08)
- Re: cpu needed to NAT 45mbs Jeff Kell (Nov 08)
- RE: cpu needed to NAT 45mbs David Schwartz (Nov 08)
- Re: cpu needed to NAT 45mbs Deepak Jain (Nov 08)
- Re: cpu needed to NAT 45mbs Joe Greco (Nov 08)
- Re: cpu needed to NAT 45mbs Christopher Morrow (Nov 08)
- Re: cpu needed to NAT 45mbs Lamar Owen (Nov 09)
- Re: cpu needed to NAT 45mbs Suresh Ramasubramanian (Nov 09)
- Re: cpu needed to NAT 45mbs Adrian Chadd (Nov 09)
- Re: cpu needed to NAT 45mbs Joel Jaeggli (Nov 10)
- RE: cpu needed to NAT 45mbs Frank Bulk (Nov 12)
- Re: cpu needed to NAT 45mbs Randy Bush (Nov 12)
- Re: cpu needed to NAT 45mbs Joel Jaeggli (Nov 12)
- Re: cpu needed to NAT 45mbs Carl Karsten (Nov 12)
- Re: cpu needed to NAT 45mbs Suresh Ramasubramanian (Nov 09)
- RE: cpu needed to NAT 45mbs Darden, Patrick S. (Nov 08)