Re: [Xen-users] xen and .1q vlans

[Javier Guerra <javier@xxxxxxxxxxx>]

On Tuesday 19 December 2006 9:39 am, Alessio Mineni wrote:
> It happen that I can "ping" the DomU but I can't "ssh" on it; the netstat

try different ping packet sizes (eg: ping -s 1500), several common problems 
with vlans affect only packets over 1496 bytes long.

check that eth1's MTU is at least 4 bytes bigger than vlanX's MTU.  if vlan2 
has an MTU of 1500, eth1 must have at least 1504.

some people like to turn down vlanX MTU to 1496, but that doesn't work if the 
vlan device is used for bridging and not routing.  (that's because the MTU 
discovery is done watching for the 'fragmentation needed' ICMP packets, but a 
bridge doesn't fragment, it simply drops what it can't handle)


-- 
Javier

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