RE: [Xen-devel] bridge + arp

["Phil Winterfield (winterfi)" <winterfi@xxxxxxxxx>]

Moritz,

I am seeing something very similar - see 
http://lists.xensource.com/archives/html/xen-devel/2008-09/msg00686.html

It looks as though the responses to arp requests are being dropped by the 
bridge, causing a halt in packet forwarding. Interestingly, the packet drop 
occurs even if I manually fill in the arp table with the entry. I am running 
with xen-unstable c/s 18242.

Phil

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-
> bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Moritz Möller
> Sent: Friday, September 19, 2008 11:59 AM
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-devel] bridge + arp
> 
> Hi,
> 
> this is propably bridge related and not really a xen problem, but it
> might help someone:
> 
> Some of our domUs are not able to arp. Arp -n show (incomplete), and
> doing a tcpdump shows, that on the dom0's eth0 the arp request goes out,
> the response comes in, but on the vifX.0 interface the arp response is
> gone.
> 
> dom0# tcpdump -ni eth0
> arp who-has 10.32.2.51 tell 10.32.7.70
> arp reply 10.32.2.51 is-at 00:30:48:34:44:6c
> 
> dom0# tcpdump -ni br0
> arp who-has 10.32.2.51 tell 10.32.7.70
> arp reply 10.32.2.51 is-at 00:30:48:34:44:6c
> 
> dom0# tcpdump -ni vif3.0
> arp who-has 10.32.2.51 tell 10.32.7.70
> 
> Does someone know why the dom0 br0 or vif eats the arp response?
> 
> Thanks a lot,
> 
> Moritz
> 
> 
> ip a l
> 1: lo: <LOOPBACK,UP,10000> mtu 16436 qdisc noqueue
>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>     inet 127.0.0.1/8 scope host lo
>     inet6 ::1/128 scope host
>        valid_lft forever preferred_lft forever
> 2: eth0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc pfifo_fast qlen
> 1000
>     link/ether 00:30:48:34:13:dc brd ff:ff:ff:ff:ff:ff
>     inet6 fe80::230:48ff:fe34:13dc/64 scope link
>        valid_lft forever preferred_lft forever
> 3: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 1000
>     link/ether 00:30:48:34:13:dd brd ff:ff:ff:ff:ff:ff
> 4: br0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc noqueue qlen 20000
>     link/ether 00:30:48:34:13:dc brd ff:ff:ff:ff:ff:ff
>     inet 10.32.2.50/14 brd 10.35.255.255 scope global br0
>     inet6 fe80::230:48ff:fe34:13dc/64 scope link
>        valid_lft forever preferred_lft forever
> 5: vif1.0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc pfifo_fast qlen
> 32
>     link/ether fe:ff:ff:ff:ff:ff brd ff:ff:ff:ff:ff:ff
>     inet6 fe80::fcff:ffff:feff:ffff/64 scope link
>        valid_lft forever preferred_lft forever
> 6: vif2.0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc pfifo_fast qlen
> 32
>     link/ether fe:ff:ff:ff:ff:ff brd ff:ff:ff:ff:ff:ff
>     inet6 fe80::fcff:ffff:feff:ffff/64 scope link
>        valid_lft forever preferred_lft forever
> 7: vif3.0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc pfifo_fast qlen
> 32
>     link/ether fe:ff:ff:ff:ff:ff brd ff:ff:ff:ff:ff:ff
>     inet6 fe80::fcff:ffff:feff:ffff/64 scope link
>        valid_lft forever preferred_lft forever
> 
> 
> brctl show
> bridge name     bridge id               STP enabled     interfaces
> br0             8000.0030483413dc       no              eth0
>                                                         vif1.0
>                                                         vif2.0
>                                                         vif3.0
> 
> 
> 
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