RE: [Xen-users] Xen Windows Clients - BSOD withApplicationFirewallInstalls

[<xensource.2007@xxxxxxxxxxxxxxxxx>]

Thanks James
But it makes no dif. Am I applying it to the correct interface (xenbr1)?


-----Original Message-----
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of James Harper
Sent: Monday, 24 March 2008 6:49 PM
To: xensource.2007@xxxxxxxxxxxxxxxxx; Rudi Ahlers; xen-users@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xen-users] Xen Windows Clients - BSOD 
withApplicationFirewallInstalls


> 6) At firewall startup, BSOD
> 7) Subsequent restarts result in BSOD as previously stated.

Xen appears to be sending 'large' packets onto the bridge, and the tap 
interface isn't 'un-large-ing' them.

"
20:40:34.437312 IP (tos 0x0, ttl 128, id 34470, offset 0, flags [DF],
proto: TCP (6), length: 52) 192.168.207.200.5001 >
192.168.207.254.53981: ., cksum 0x05aa (correct), 1:1(0) ack 14505 win 58295 
<nop,nop,timestamp 57828874 1445680997> 20:40:34.437324
IP (tos 0x0, ttl  64, id 51510, offset 0, flags [DF],
proto: TCP (6), length: 4396) 192.168.207.254.53981 >
192.168.207.200.5001: . 23193:27537(4344) ack 1 win 46 <nop,nop,timestamp 
1445680998 57828874> 20:40:34.439653 IP (tos 0x0, ttl 128,
id 34471, offset 0, flags [DF],
proto: TCP (6), length: 64) 192.168.207.200.5001 >
192.168.207.254.53981: ., cksum 0x2a79 (correct), 1:1(0) ack 15953 win 56847 
<nop,nop,timestamp 57828874 1445680997,nop,nop,sack 1
{17401:18849}> 20:40:34.439670 IP (tos 0x0, ttl  64, id 51513, offset 0, flags 
[DF],
proto: TCP (6), length: 4396) 192.168.207.254.53981 >
192.168.207.200.5001: . 27537:31881(4344) ack 1 win 46 <nop,nop,timestamp 
1445680999 57828874> "

Note the lengh of 4396 - the hardware interface is supposed to break that up 
into MSS sized chunks, but there is no hardware
interface involved in this case.

I'm trying to resolve the problem in the GPL PV drivers.

I've had wireshark (npf.sys) BSOD when it receives a packet with a size greater 
than MTU, so I imagine a firewall may well do the
same thing.

Try turning off large send offload for all interfaces on the bridge (the same 
bridge as your crashing DomU), eg:

"
ethtool -K <ifname> gso off
"

Iperf gives horrible results too when DomU is the 'server' and Dom0 is the 
'client' because of this.

James


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