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[Xen-users] Problem bridging multiple NICs

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] Problem bridging multiple NICs
From: Jason Kwon <jason.kwon@xxxxxxxxxxxx>
Date: Wed, 02 Sep 2009 18:57:11 -0700
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Based on other postings describing how to set up bridging for multiple
NICs, I've successfully bridged multiple physical devices on my Xen
system.  However, I'm observing some strange network behavior.

First, let me describe my setup.  I have three NICs, eth0, eth1, eth2.
I modified xend-config.sxp as follows:

#(network-script network-bridge)
(network-script my-network-bridge)

my-network-bridge is as follows:

dir=$(dirname "$0")
"$dir/network-bridge" "$@" vifnum=0 netdev=eth0   bridge=xenwan0
"$dir/network-bridge" "$@" vifnum=1 netdev=eth1   bridge=xenlan1
"$dir/network-bridge" "$@" vifnum=2 netdev=eth2   bridge=xenlan2

I did not change vif-bridge.  I couldn't determine whether that was
necessary or not.

'brctl show' gives:

bridge name     bridge id               STP enabled     interfaces
virbr0          8000.000000000000       yes
xenlan1         8000.feffffffffff       no              peth1
xenlan2         8000.feffffffffff       no              peth2
xenwan0         8000.feffffffffff       no              peth0

I have static IP addresses assigned to each NIC.  Simple network
activity like ping or ssh works on all three physical links.  However,
when I started an nuttcp server on this machine ('nuttcp -S'), running
an nuttcp client from another machine only works when connecting to eth0
on the server; if I attempt to connect an nuttcp client to eth1 or eth2
on the Xen machine, I get:

nuttcp-t: v6.1.2: Error: server not ACKing data

Similarly, if I run an NFS server from the Xen machine, file transfer
to/from other machines is extremely slow, except when mounting from the
eth0 connection.  Clearly, something is going wrong with the
bridging/routing on my Xen machine.

I have not started any DomU guests on this machine.  If I turn off
network bridging in the Xen configuration, then everything returns to
normal (I can run nuttcp/NFS across all three links at normal speed), so
something with the bridging and renaming of the physical links is
affecting network behavior.

I'm running CentOS 5.3, Xen 3.0.3.  Can anyone tell me if I've
configured something wrong?



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