Re: [Xen-users] Massive numbers of dropped packets / ssh problems

[tom.ashley@xxxxxxxxx]

That actaully sounds like a reverse dns lookup issue from your server.
Make sure the ssh server can resolve the ip you are coming from.

Tom
Sent using BlackBerry® from Orange

-----Original Message-----
From: Joel Richard <xen@xxxxxxxxxxxxxxx>

Date: Sat, 7 Mar 2009 08:08:49 
To: <xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-users] Massive numbers of dropped packets / ssh problems


Good morning,

I'm hoping that someone can help me out with this. I recently moved a  
running server from an internal network to a public-facing network  
(moved from our office to a data center)

Prior to this, we had no trouble with the server, but since we've put  
it on the net and gave it some public IPs (versus the 192.168.x.x  
addresses it had before) we've had trouble with SSH and Web  
connections onto one of the DomU servers (possibly all of them). That  
is, sometimes when we connect from SSH or HTTP, it will sometimes  
"time out" somehow (not your usual connection timed out) and we need  
to try again a couple of times to get the server to respond. It seems  
to happen most when the server has been idle for some time, like first  
thing in the morning.

On the Dom0 if I do an ifconfig, I get the info that's at the bottom  
of this message (IPs have been changed to protect the innocent) The  
server has 4 DomU's running on it.

Note that the peth1 interface has 79 billion dropped packets. The  
server has been running for a week. My first thought is "what the  
hell?" :) I can't find those dropped packets with tcpdump and yet I am  
convinced that this is a problem.

When we SSH into the server (the DomU), sometimes it will hang with  
this information:

(my laptop) $ ssh -v XXX.XXX.XXX.XXX

OpenSSH_5.0p1, OpenSSL 0.9.7l 28 Sep 2006
debug1: Reading configuration data /Users/joel/.ssh/config
debug1: Applying options for dev
debug1: Reading configuration data /etc/ssh_config
debug1: Connecting to dev.richard-group.com [XXX.XXX.XXX.XXX] port 22.
debug1: Connection established.
debug1: identity file /Users/joel/.ssh/identity type -1
debug1: identity file /Users/joel/.ssh/id_rsa type 1
debug1: identity file /Users/joel/.ssh/id_dsa type 2

Yes, that's where it stops. It's already established the connection,  
but it doesn't continue. It initially sounds like an SSH problem, but  
it seems more to me something possibly between the Dom0 and the DomU.  
I do not have this problem with ssh on a real server on the same  
network that is not using Xen.

To clarify, I am using Debian Etch, Xen 3.0.3, AMD Phenom CPUs,  
2.6.18-6-xen-amd64 #1 SMP kernel. We're using the onboard NIC.

Can anyone help?

Thanks a lot.
--Joel


(dom0) # ifconfig

eth1      Link encap:Ethernet  HWaddr 00:1F:D0:99:C8:1D
          inet addr:XXX.XXX.XXX.XXX  Bcast:XXX.XXX.XXX.XXX  Mask: 
255.255.255.192
          inet6 addr: XXX.XXX.XXX.XXX/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:790038 errors:0 dropped:0 overruns:0 frame:0
          TX packets:30111 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:259565273 (247.5 MiB)  TX bytes:8294720 (7.9 MiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

peth1     Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:3231189 errors:0 dropped:79653025568 overruns:0  
frame:0
          TX packets:1839869 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1834207650 (1.7 GiB)  TX bytes:617376732 (588.7 MiB)
          Interrupt:16 Base address:0xa000

vif0.1    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:30111 errors:0 dropped:0 overruns:0 frame:0
          TX packets:790038 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:8294720 (7.9 MiB)  TX bytes:259565273 (247.5 MiB)

vif1.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:1621897 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2841674 errors:0 dropped:1371 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:437418179 (417.1 MiB)  TX bytes:2168128688 (2.0 GiB)

vif2.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:10114591 errors:0 dropped:0 overruns:0 frame:0
          TX packets:11032176 errors:0 dropped:244457 overruns:0  
carrier:0
          collisions:0 txqueuelen:0
          RX bytes:8708636564 (8.1 GiB)  TX bytes:10165626759 (9.4 GiB)

vif4.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:10714696 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10554522 errors:0 dropped:220230 overruns:0  
carrier:0
          collisions:0 txqueuelen:0
          RX bytes:10211262961 (9.5 GiB)  TX bytes:8503978649 (7.9 GiB)

vif8.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:6432 errors:0 dropped:0 overruns:0 frame:0
          TX packets:39471 errors:0 dropped:50 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1485151 (1.4 MiB)  TX bytes:12072170 (11.5 MiB)

xenbr1    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
          inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
          RX packets:579865 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:113821662 (108.5 MiB)  TX bytes:0 (0.0 b)

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