Current state of FreeBSD routing

[Eugene Grosbein]

On 02.02.2011 05:11, Markus Oestreicher wrote:

> 2) Fastforwarding vs multiple netisr:
> In the past (6.x) using fastforwarding=1 was the best option for dedicated routers.
> I found "multiple netisr" added to 8.0. Can that help with routing on multiple cores?

Yes, it allows more even distribution of input traffic processing over cores.

> Any experience from using it in production?

It helps greatly but I was forced to disable it for mpd-based router
where there are many dynamically born/destroyed network interfaces.

I suspect it increases possibility of kernel panic in such configuration
due to famous 'dangling pointer' problem: an interface ngXXX got destroyed
while packets received from it reside in netisr queues. Then kernel might
panic while processing these packets if needs to check incoming interface,
f.e. due to ipfw antispoofing rules.

> 3) lagg:
> I found lagg(4) mostly mentioned on home user setups.
> Any experience with using lagg in high-pps environments? (>100k pps)

Works fine for me.

> Will lagg play nicely together with multiple netisr routing or fastforwarding?
> How much overhead will it add versus a single connection?

Unnoticed.

Eugene Grosbein