[Openstack] Strange network behavior

Joe Warren-Meeks joe.warren.meeks at gmail.com
Fri Nov 9 17:14:18 UTC 2012


Hi all,

I've managed to get Openstack pretty much up and running as I wanted it. I
do have, however, a rather strange networking issue.

I created the network with
nova-manage network create --fixed_range_v4=10.0.41.0/24 --num_networks=1
--bridge=br41 --bridge_interface=eth0 --label=development
--gateway=10.0.41.1 --dns1=10.0.0.2 --vlan=41 --project_id=XXXXXXX

And i can boot instances fine. I've configured the default security group
to allow port 22, 80 and ICMP -1 in and I can ping from my work station to
the virtual instance ok:

joe at kaneda:~$ ping 10.0.41.3
PING 10.0.41.3 (10.0.41.3) 56(84) bytes of data.
64 bytes from 10.0.41.3: icmp_req=1 ttl=63 time=1.18 ms

And i can ping from the virt back too:
ubuntu at test:~$ ping 10.0.0.240
PING 10.0.0.240 (10.0.0.240) 56(84) bytes of data.
64 bytes from 10.0.0.240: icmp_req=1 ttl=64 time=0.713 ms


I can SSH out from the virt to a host in the outside world fine:
ubuntu at test:~$ ssh joe at XXXXX
joe at XXXXXX password:
-bash: fortune: command not found
joe at dixon:~ $

BUT I can't ssh from the virt to my workstation, nor from my workstation to
the Virt. Neither does http work.

What I am seeing in Tcpdump is a lot of incorrect cksums. This happens with
all Tcp connections.

17:12:38.539784 IP (tos 0x0, ttl 64, id 53611, offset 0, flags [DF], proto
TCP (6), length 60)
    10.0.0.240.56791 > 10.0.41.3.22: Flags [S], cksum 0x3e21 (incorrect ->
0x6de2), seq 2650163743, win 14600, options [mss 1460,sackOK,TS val
28089204 ecr 0,nop,wscale 6], length 0


17:12:38.585279 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP
(6), length 60)
    10.0.41.3.22 > 10.0.0.240.56791: Flags [S.], cksum 0x3e21 (incorrect ->
0xe5c5), seq 1530502549, ack 3098447117, win 14480, options [mss
1460,sackOK,TS val 340493 ecr 28089204,nop,wscale 3], length 0

Anyone come across this before?

 -- joe.
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