Odd Bridging Quirk

Odd Bridging Quirk

[Chris Babcock]

I am seeing an odd bridging quirk, on my domU instances.

When any of my domU's start, they cannot receive any traffic until they
have sent at least a few packets.  Time seems to have no effect on this
behavior.  If I let an idle domU sit for an hour, it still fails to
receive, if it has not originated any traffic.

My workaround for the moment, is an added rc-init script that pings the
default gateway a few times when the domain first comes up.

Is this normal? Should there be a warning in the docs, if it is?  If not,
does anybody have any ideas what may be causing this?

-CRB

Re: Odd Bridging Quirk

[Josh Triplett]

Chris Babcock wrote:
> I am seeing an odd bridging quirk, on my domU instances.
> 
> When any of my domU's start, they cannot receive any traffic until they
> have sent at least a few packets.  Time seems to have no effect on this
> behavior.  If I let an idle domU sit for an hour, it still fails to
> receive, if it has not originated any traffic.
> 
> My workaround for the moment, is an added rc-init script that pings the
> default gateway a few times when the domain first comes up.
> 
> Is this normal? Should there be a warning in the docs, if it is?  If not,
> does anybody have any ideas what may be causing this?

I think I remember having this same problem when I set up networking 
with Xen.  How are your domains getting their network addresses?  I 
think the problem may have had something to do with ARP not being 
correctly set up between the bridge, the DomU's, and the network, such 
that a domain needed to send some packets out before it was known to 
have a given address.

- Josh Triplett

RE: Odd Bridging Quirk

[James Harper]

What network card(s) are you using?

Do you have any firewall rules that might be operating at the bridge
level?

James

> -----Original Message-----
> From: xen-devel-bounces@lists.xensource.com [mailto:xen-devel-
> bounces@lists.xensource.com] On Behalf Of Chris Babcock
> Sent: Tuesday, 21 June 2005 08:42
> To: xen-devel@lists.xensource.com
> Subject: [Xen-devel] Odd Bridging Quirk
> 
> I am seeing an odd bridging quirk, on my domU instances.
> 
> When any of my domU's start, they cannot receive any traffic until
they
> have sent at least a few packets.  Time seems to have no effect on
this
> behavior.  If I let an idle domU sit for an hour, it still fails to
> receive, if it has not originated any traffic.
> 
> My workaround for the moment, is an added rc-init script that pings
the
> default gateway a few times when the domain first comes up.
> 
> Is this normal? Should there be a warning in the docs, if it is?  If
not,
> does anybody have any ideas what may be causing this?
> 
> -CRB
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

RE: Odd Bridging Quirk

[Chris Babcock]

lspci reports:
Ethernet controller: Broadcom Corporation NetXtreme BCM5704S Gigabit
Ethernet (rev 10)

dmesg reports:
eth0: Tigon3 [partno(BCM95704A41) rev 2100 PHY(serdes)]
(PCIX:133MHz:64-bit) 10/100/1000BaseT Ethernet 00:11:25:4a:9a:4a
eth0: RXcsums[1] LinkChgREG[0] MIirq[0] ASF[1] Split[0] WireSpeed[1]
TSOcap[0]

No firewalling rules of any kind have been configured.  The default vendor
(debian) system config does not include firewalling rules.  I am currently
using the binary kernel provided in the Xen stable 2.0.6 distribution
(base kernel version 2.6.11.10).

> What network card(s) are you using?
>
> Do you have any firewall rules that might be operating at the bridge
> level?
>
> James
>
>> -----Original Message-----
>> From: xen-devel-bounces@lists.xensource.com [mailto:xen-devel-
>> bounces@lists.xensource.com] On Behalf Of Chris Babcock
>> Sent: Tuesday, 21 June 2005 08:42
>> To: xen-devel@lists.xensource.com
>> Subject: [Xen-devel] Odd Bridging Quirk
>>
>> I am seeing an odd bridging quirk, on my domU instances.
>>
>> When any of my domU's start, they cannot receive any traffic until
> they
>> have sent at least a few packets.  Time seems to have no effect on
> this
>> behavior.  If I let an idle domU sit for an hour, it still fails to
>> receive, if it has not originated any traffic.
>>
>> My workaround for the moment, is an added rc-init script that pings
> the
>> default gateway a few times when the domain first comes up.
>>
>> Is this normal? Should there be a warning in the docs, if it is?  If
> not,
>> does anybody have any ideas what may be causing this?
>>
>> -CRB
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@lists.xensource.com
>> http://lists.xensource.com/xen-devel
>
>

Re: Odd Bridging Quirk

[Chris Babcock]

> Chris Babcock wrote:
>> I am seeing an odd bridging quirk, on my domU instances.
>>
>> When any of my domU's start, they cannot receive any traffic until they
>> have sent at least a few packets.  Time seems to have no effect on this
>> behavior.  If I let an idle domU sit for an hour, it still fails to
>> receive, if it has not originated any traffic.
>>
>> My workaround for the moment, is an added rc-init script that pings the
>> default gateway a few times when the domain first comes up.
>>
>> Is this normal? Should there be a warning in the docs, if it is?  If
>> not,
>> does anybody have any ideas what may be causing this?
>
> I think I remember having this same problem when I set up networking
> with Xen.  How are your domains getting their network addresses?  I

The domains are being assigned their address in the debian startup
sequence from /etc/network/interfaces inside the domU instance.


> think the problem may have had something to do with ARP not being
> correctly set up between the bridge, the DomU's, and the network, such
> that a domain needed to send some packets out before it was known to
> have a given address.
>
> - Josh Triplett
>

Re: Odd Bridging Quirk

[Nivedita Singhvi]

Chris Babcock wrote:
> lspci reports:
> Ethernet controller: Broadcom Corporation NetXtreme BCM5704S Gigabit
> Ethernet (rev 10)
> 
> dmesg reports:
> eth0: Tigon3 [partno(BCM95704A41) rev 2100 PHY(serdes)]
> (PCIX:133MHz:64-bit) 10/100/1000BaseT Ethernet 00:11:25:4a:9a:4a
> eth0: RXcsums[1] LinkChgREG[0] MIirq[0] ASF[1] Split[0] WireSpeed[1]
> TSOcap[0]
> 
> No firewalling rules of any kind have been configured.  The default vendor
> (debian) system config does not include firewalling rules.  I am currently
> using the binary kernel provided in the Xen stable 2.0.6 distribution
> (base kernel version 2.6.11.10).
> 

Does your vm get correctly configured (IP address, gw, route, etc)?
What does arp -avn show when it's in that state?

thanks,
Nivedita