From: Herbert Poetzl (herbert_at_13thfloor.at)
Date: Thu 15 Apr 2004 - 17:01:11 BST
On Thu, Apr 15, 2004 at 03:26:38PM +0100, Chris Wilson wrote:
> Hi Cathy,
> > > are you 100% sure that this isn't some hidden
> > > arp table flushing / router not routing issue?
> > I had similar problems (similarly affecting only the vserver IPs, not the
> > master server) that coincided with a router upgrade in the data center. I
> > second Herbert's suggestion to check the router. :) HTH.
> I will, but I definitely observed repeated incoming ARP requests for an IP
> that I thought was configured on the server, although I neglected to
> capture evidence. The addresses had not previously been assigned, so I
> don't think there could be an ARP table entry to flush, and having
> restarted the vservers it once again became possible to access them
> without any changes to the firewall.
> I will investigate further when I can afford potential downtime,
> and capture a tcpdump and the output of "ip link show", "ip route show"
> and "arp -n" to prove that the machine is not responding to ARPs. Is there
> anything else I should capture?
> Is it possible that "vserver X stop" does not always take down the right
yes, under yet unknown circumstances, it happens
that the vserver tools (or the ip/ifconfig utility)
creates the alias as primary IP, in which case a
vserver down (for this alias) will take down the
entire interface (which is the right thing to do
for primary ip addrs, which should not be used by
vserver tools) ...
this can cause other servers to become disfunctional
after a vserver stop (which you didn't mention ;)
you can verify such a mis-configuration with
ip addr show
on the host, which should only list secondary aliases
for the vservers IPs ...
> Cheers, Chris.
> _ __ __ _
> / __/ / ,__(_)_ | Chris Wilson -- UNIX Firewall Lead Developer |
> / (_ ,\/ _/ /_ \ | NetServers.co.uk http://www.netservers.co.uk |
> \__/_/_/_//_/___/ | 21 Signet Court, Cambridge, UK. 01223 576516 |
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