Fragmentation and CSM

[edaguet]

Hello,

I have defined a vserver with a VIP. When remote user try to connect to the VIP through a GRE tunnel, the last router send a "fragmentation needed" (ICMP 3/4) to the CSM. My question is:

how specify the max length of the packet from the CSM.?

For example, i would like that the CSM send a packet of 1300 bit max instead of 1460.

[Gilles Dufour]

The ICMP 3/4 sent to the CSM is actually forwarded to the server and it is up to the server to adjust it's packet size.

This however was only fixed in the latest 3.2 version and in 4.x.

The CSM does not modify packet size unless you have a L7 vserver.

In this case, you could use the following parameter to adjust the MSS - TCP_MSS_OPTION - but it would affect all connections, not just the one coming over GRE tunnel.

In conclusion, you should verify that the icmp packet is forwarded to the server and that the server is correctly adjusting the packet size.

If the icmp is not forwarded, make sure the following bug has been fixed in your version

CSCeb55530: CSM not forwarding icmp 3/4 to real server

Regards,

Gilles.