[Rdo-list] [RDO] rkukura commented on a discussion.

RDO Forum rdo-info at redhat.com
Tue Jun 18 19:25:28 UTC 2013

rkukura commented on a discussion.

Hi Steven,

The VLAN tags are being modified by OVS flow rules as packets cross the veth connecting the bridges. These flows can be displayed using ovs-ofctl as follows:

ovs-ofctl dump-flows br-int

NXST_FLOW reply (xid=0x4):

 cookie=0x0, duration=947602.247s, table=0, n_packets=150980, n_bytes=37605726, idle_age=1, hard_age=65534, priority=1 actions=NORMAL

 cookie=0x0, duration=947598.9s, table=0, n_packets=16652192, n_bytes=1367674080, idle_age=0, hard_age=65534, priority=2,in_port=2 actions=drop

 cookie=0x0, duration=110.96s, table=0, n_packets=4, n_bytes=1158, idle_age=48, priority=3,in_port=2,dl_vlan=1000 actions=mod_vlan_vid:2,NORMAL

ovs-ofctl dump-flows br-eth2

NXST_FLOW reply (xid=0x4):

 cookie=0x0, duration=947604.202s, table=0, n_packets=17266871, n_bytes=1429653351, idle_age=0, hard_age=65534, priority=1 actions=NORMAL

 cookie=0x0, duration=947601.253s, table=0, n_packets=31, n_bytes=2318, idle_age=113, hard_age=65534, priority=2,in_port=4 actions=drop

 cookie=0x0, duration=113.882s, table=0, n_packets=107, n_bytes=6118, idle_age=1, priority=4,in_port=4,dl_vlan=2 actions=mod_vlan_vid:1000,NORMAL

[root at rachel ~(keystone_bob)]#

In this case, the local VLAN tag on br-int is 2, and the VLAN tag on the physical network (br-eth2) is 1000.

Whether you need to enable VLAN splinters depends on what NIC driver you are using.  I have not needed to run commands such as "ovs-vsctl set port eth2 trunks-81,82".

We will be working to characterize any performance overhead from using multiple bridges connected by veths, and may explore a single-bridge solution if justified.

Hope this helps,


Follow the link below to check it out:

Have a great day!

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