[quagga-dev 1026] Re: Linux and netlink

Hasso Tepper hasso at estpak.ee
Thu Apr 8 08:57:13 BST 2004

Paul Jakma wrote:
> On Wed, 7 Apr 2004, Hasso Tepper wrote:
> > 1) Increasing buffer size with SO_RCVBUF. I got it working with
> > huge buffers, but I wouldn't rely on it in production system.
> > There is no way I can quarantee that I don't hit limit again if
> > number of vlan interfaces is increased.
> >
> > But all this netlink stuff sounds quite dangerous for me and
> > should be fixed somehow IMHO. According to linux network
> > developers correct solution would be detect that something was
> > lost and resync:
> >
> > http://oss.sgi.com/projects/netdev/archive/2001-01/msg00215.html
> > (whole thread is quite interesting reading)
> Yep.
> And one of the things I'd like to do soonish is get workqueues nice
> enough to merge in (tisnt at moment), then one of the things that
> can make use of it is rt_netlink to keep proper track of and also
> coalesce netlink requests.
> > Ideas?
> Lets bump the buffer up for 0.96.5.

It's not so easy. From man 7 socket:

Sets  or  gets  the maximum socket receive buffer in bytes. The 
default value is set by the rmem_default sysctl and the maximum 
allowed value is set by the rmem_max sysctl.

hasso at test3:/proc/sys$ cat /proc/sys/net/core/rmem_default
hasso at test3:/proc/sys$ cat /proc/sys/net/core/rmem_max

I got my router working with 524280. Btw, it depends what features you 
have enabled in router. Enabled multicast and ipv6 make things worse 
of course (more routes are added when interface is upped).

It wasn't so bad with older zebra, btw and I have feeling that one 
patch (http://marc.theaimsgroup.com/?l=zebra&m=102379207214720&w=2) 
made things worse.

Hasso Tepper
Elion Enterprises Ltd.
WAN administrator

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