Re: [Xen-users] crc checksum problems

[Daniel Goertzen <goertzen@xxxxxxxx>]

I observed similar problems (checksum errors) when I directly assigned 
an IP address to the bridge in dom0.  I corrected the situation by 
adding vif0.0 to the bridge and assigning the IP address to veth0.  If 
you're using the network-bridge script that comes with xend this all 
happens automatically, but I had to roll my own solution and ran afoul.
Dan.

Renà Pfeiffer wrote:

> On Jan 03, 2006 at 2041 -0800, Charles Mauch appeared and said:
>  
>
> > [...]
> > I have xen setup with a wrapper that establishes three bridges in xen,
> > which I named red, orange, and green.  eth0 is my public interface and is a
> > 3com card, bound to the red bridge.  eth1 is my dmz interface, a forcedeth
> > (nvidia card), and it is bound to orange.  dummy0 is bound to green, and
> > all domU's on this bridge are in the 192.168.1.0 network, including dom0.
> > [...]
> >
> > When I upgrade to xen3, I experience tcp and udp checksum errors when
> > attempting to route any traffic through my firewall/router. 
> >    
> I have a similar albeit simpler setup. My Dom0 is connected to the
> Internet. The "first" DomU is a firewall, the second DomU is a web server.
> The first bridge connects physical interface with the firewall's
> exterior virtual interface. The second bridge connects firewall and
> webserver to form a kind of LAN.
>
> Firewalling and routing with NAT is all set up. However as soon as data
> packets flow between web server and a client I get TCP checksum errors.
> The TCP handshake works fine. A.A.A.A is the firewall's IP, B.B.B.B is a
> client:
>
> client:/root# tethereal -n -i eth0 host A.A.A.A
> Capturing on eth0
>  0.000000 B.B.B.B -> A.A.A.A TCP 41721 > 80 [SYN, ECN, CWR] Seq=0 Ack=0 
> Win=5840 Len=0 MSS=1460 TSV=333318731 TSER=0 WS=2
>  0.009362 A.A.A.A -> B.B.B.B TCP 80 > 41721 [SYN, ACK] Seq=0 Ack=1 Win=5792 
> Len=0 MSS=1460 TSV=2958428 TSER=333318731 WS=2
>  0.009434 B.B.B.B -> A.A.A.A TCP 41721 > 80 [ACK] Seq=1 Ack=1 Win=5840 Len=0 
> TSV=333318733 TSER=2958428
>  0.035842 A.A.A.A -> B.B.B.B TCP 80 > 41721 [PSH, ACK] Seq=1 Ack=1 Win=5792 
> [TCP CHECKSUM INCORRECT] Len=23 TSV=2958430 TSER=333318733
>  0.243444 A.A.A.A -> B.B.B.B TCP [TCP Retransmission] 80 > 41721 [PSH, ACK] 
> Seq=1 Ack=1 Win=5792 [TCP CHECKSUM INCORRECT] Len=23 TSV=2958451 TSER=333318733
>  0.663784 A.A.A.A -> B.B.B.B TCP [TCP Retransmission] 80 > 41721 [PSH, ACK] 
> Seq=1 Ack=1 Win=5792 [TCP CHECKSUM INCORRECT] Len=23 TSV=2958493 TSER=333318733
>  1.501512 A.A.A.A -> B.B.B.B TCP [TCP Retransmission] 80 > 41721 [PSH, ACK] 
> Seq=1 Ack=1 Win=5792 [TCP CHECKSUM INCORRECT] Len=23 TSV=2958577 TSER=333318733
>  3.183639 A.A.A.A -> B.B.B.B TCP [TCP Retransmission] 80 > 41721 [PSH, ACK] 
> Seq=1 Ack=1 Win=5792 [TCP CHECKSUM INCORRECT] Len=23 TSV=2958745 TSER=333318733
>  6.539707 A.A.A.A -> B.B.B.B TCP [TCP Retransmission] 80 > 41721 [PSH, ACK] 
> Seq=1 Ack=1 Win=5792 [TCP CHECKSUM INCORRECT] Len=23 TSV=2959081 TSER=333318733
> ...
>
>  
>
> > I tried to enable "ethtool -K ethX tx off" in all of my domU's without
> > success. 
> >    
> What NIC are you using? Mine is a Broadcom with the tg3 driver.
>
>  
>
> > Oh, and I see the same behavior in the binary and custom-compiled kernels,
> > both the 3.0.0 release and the snapshot as of 2005-12-31.
> >    
> I am using a 3.0.0 system with the changeset from "Thu Dec 15 20:57:27
> 2005 +0100 8259:5baa96bedc13". The machine was installed on 21 December
> 2005.
>
> Best regards,
> Lynx.
>
>  


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