On Tue, Mar 13, 2012 at 05:16:26PM +1100, Virgil wrote:
> Hi List,
> I have a strange issue someone, hopefully, can advise me on.
> I have two external connections into a host: em1 is behind a firewall machine 
> which is connected to an internet backbone link, while em2 is an adsl all-u-
> can-eat deal with a cheap router.
> Both are bridged. So there's pem1 and pem2 which are connected to the em1 and 
> em2 bridges respectively.
> There is a domU router which nats (and is connected to both bridges).
> Some domU servers (a variety of fc6 to fc16 32 and 64) default route to the 
> domU router and go out the all-u-can-eat link.
> The issue is, I recent upgraded the host from Fedora8 to Fedora16, and now 
> the 
> domU machines that once happily used the all-u-can-eat link, no longer can.
> However, in an act of desperation, I moved one of the domUs to a backup 
> machine. Nothing else changed. Bingo. That domU works. All resources are 
> still 
> on the original machine (i.e. the DB servers, the router, etc. etc.).
> It seems that the router does't seem to nat domUs on the same host. You move 
> the domU off with comms going via em1 to another host and it works.
> Iptraf tracing seems to indicate that the TCP connection is setup. The first 
> packet goes off and is acked. Then everything stops and eventually the tcp 
> connection closes on the router, but the domU and the remote computer think 
> the link is still up (at least that's what I think is happening). The domU's 
> send queue ends up with lots of data in it according to 'netstat -ant'
> Only nat'd tcp connections are effected. Connections to machines on the same 
> bridge work fine.
> Does this sound familiar to anyone?

How big is the packet. There is a bug we found in netback where a specific
length of a packet causes netback to stall. Patches will be visible soon
once we have run through all the regression tests.

> Thanks in advance
> Virgil
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