Re: [Xen-devel] ARP problems in -testing?

[Felipe Alfaro Solana <lkml@xxxxxxx>]

On 16 Jan 2005, at 17:42, Ron Watkins wrote:

> I'm seeing something rather unusual that I thought might be an ARP 
> problem, but further testing appears to have ruled that out.
> Scenario:  slave domains with random ARP addresses.  On a fresh start 
> of a domain, it is unreachable from outside.  Pinging from Domain 0 to 
> the slave domain work fine, but changes nothing.
> Here's the interesting part: pinging from the slave domain to any 
> external host, including Domain 0, also works... and immediately 
> 'unsticks' the net connection, so that everything works as I expect it 
> to.
I'm experiencing this problem too... The workaround I'm using is to 
include a "ping -c2 some_outside_IP" inside the init scripts of the 
slave xenU domain, and it works, but it's an ugly hack.
> This seems to happen with or without my firewalling rules.  (I disable 
> the antispoof section of the 'network' script, so that the firewall 
> rules there don't interfere with mine.)
> My initial theory was that it's an ARP problem.  I thought the 
> outbound packet was being bridged properly to the outside world, the 
> router saw the arp address, and started working.   But this does not 
> appear to be correct. If I add a secondary IP to the eth0 inside the 
> virtual domain, I do indeed see arp requests and arp replies.
I don't know what the problem is, but running tcpdump inside the slave 
U domain, shows that packets are received by then xenU kernel, but no 
packets are sent back from the xenU kernel in response. Weird. However, 
pinging some external host from the xenU domain, seems to resolve this 
misterious problem.
> When it is in 'stuck' mode, running a tcpdump from the SLAVE domain 
> shows the echo requests arriving: [ips changed to protect the morally 
> questionable]:
> 16:36:54.694003 IP 24.0.0.10 > 69.0.0.76: icmp 40: echo request seq 
> 2344
> But there are no replies issued.    After I ping the outside world, 
> which instantly 'wakes up' the connection:
> 16:38:57.212284 IP 24.0.0.10 > 69.0.0.76: icmp 40: echo request seq 
> 11816
> 16:38:57.212314 IP 69.0.0.76 > 24.0.0.10: icmp 40: echo reply seq 11816
>
> This is from a brand-new download today, btw.
Yep! I run bk pull every day or so from xeno-unstable.

> I am really mystified.  Any suggestions?
It seems we are having the same problems :-)



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