[K42-discussion] low MTU required when accessing kcvs.watson.ibm.com

[Andrew Baumann]

Hi all,

this is for anyone accessing the K42 CVS remotely and having problems with 
their CVS checkouts "hanging". Hopefully someone having the same problem that 
I was will find this in google :)

It seems that between kcvs and the internet is a hop with a 1476-byte MTU. 
Normally this would be fine, but if you are in a situation where MTU path 
discovery doesn't work (eg. you are behind a firewall that filters out the 
ICMP packets), then a TCP connection to kcvs will appear to "hang" after the 
first large packet is sent, and eventually time out.

To workaround this problem you can do one of several things:
 * lower the MTU on your network interface for all connections
 * or disable MTU path discovery
 * or set an explicit route to kcvs's network with a low MTU, which can be
   accomplished in linux with something like:
	ip route add 129.34.2.0/24 via 203.143.160.1 mtu 1476

Hope this helps,
Andrew