Re: [Xen-users] crc checksum problems

[Renà Pfeiffer <lynx@xxxxxxxxx>]

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.

-- 
"From the delicate strands,
 between minds we weave our mesh:
 a blanket to warm the soul."
 --- Lady Deirdre Skye (SMAC) ---


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