Kernel dropped some netlink messages, will resync on next scan.

[Giuseppe Ravasio (LU)]

Hi,
I'm upgrading my core router (running an old bird 1.3.10) with a new
Ubuntu 16.04 running 1.6.3 from the official PPA.

Actually it'a a pretty simple configuration

 ISP3                  ISP1     ISP2
    |                     |        |
    |                     |        |
NEWROUTER=====<iBGP>======OLDROUTER
                               |
                               |
                          ipv4/21
                          ipv6/32       

In the new router i find a lot of messages
"Kernel dropped some netlink messages, will resync on next scan."
for both IPv6 and IPv4

For IPv6 daemon this seems to happen only when i start the sessions and
load the full table and so I think it could be acceptable.

For IPv4 daemon this seems to happen *a lot* when I start the BGP
session with the iBGP enabled (and also this I think could be
acceptable), but the message gets printed sometimes (a single line every
5/10 minutes) when the BGP is running normally.

I already tried to adjust the net.core mem kernel parameters with:
net.core.rmem_max = 8388608
net.core.wmem_max = 8388608
net.core.optmem_max = 65536
net.core.rmem_default=1064960
net.core.wmem_default=1064960

But the messages are still there.
Any hints? maybe the rmem_default is still too low?


Thanks
Giuseppe