iamjeffvader's studymotron and rantatorium

Cumulus Linux is awesome, did you know that?  I haven’t got deep in to it, really only looked at bridging so far, but here is how you configure interfaces…so I don’t forget.

Let’s keep it nice and simple.  I have two Nokia 7750 VSRs that I want to bridge together, sros3 and sros8.  Both have a single connection over port 1/1/1 to the VX switch. These connections are to connect the various VM ports to the VX from the host machines perspective.

What’s this swp stuff?  This is what Cumulus will call your interfaces: switchport basically. The management interface of the VX is eth0 and then each connection to a VM is on an swp starting at swp1 and continuing up as needed.  Port positioning/numbering is based on the sequence the bridge entries are placed in your VX XML file.  The first bridge will be eth0, the second swp1, third swp2 and so on.

My XML config for the 7750s is straightforward enough, nothing fancy going on.  This portion connects the VX to sros8 only.  You need an entry in your XML file for each port.

<interface type=’bridge’>
<mac address=’00:00:77:50:01:02’/>
<source bridge=’sros8_vx1’/>
<model type=’virtio’/>
</interface>

The equivalent on the VX is:

<interface type=’bridge’>
<mac address=’00:00:03:16:02:25’/>
<source bridge=’sros8_vx1’/>
<model type=’virtio’/>
</interface>

You can configure the sros8_vx1 bridge using VMM if you wish.  If you want to throw it in quickly you can add with brctl but it wont be persistent.

[keith@scamall-server1 ~]$ sudo brctl addbr sros8_vx1

[keith@scamall-server1 ~]$ brctl show sros8_vx1
bridge name bridge id STP enabled interfaces
sros8_vx1 8000.fe0003160225 no vnet200
vnet201

We then configure the bridge in the VX machine.  This is the ‘VLAN’ internal to the VX and connects the external VMs (sros3 and sros8) to a common forwarding table using bridge sr3_sr8.

Interface configuration files are stored in /etc/network/interfaces so edit this file as follows:

auto sr3_sr8
iface sr3_sr8 inet static
bridge-ports swp41.38 swp43.38
bridge-stp off
address 10.3.8.254
netmask 255.255.255.0

swp41 is where sros8 connects and swp43 is where sros3 connects.  The .38 is the tag I will accept for this bridge (similar configuration on the VSR).  While I don’t need to put an IPv4 address here I can use it to test connectivity between the connected VM and the VX if there is a problem.   FYI Cumulus VX comes with Nano as an editor, download VIM as quick as you can. Man I hate Nano 🙂

Finally bring up your new bridge on the VX

cumulus@cumulus:~$ sudo ifup sr3_sr8

You can also use sudo ifup -a to bring all interfaces up.

Now, where is that proof pudding for me to eat?

*A:sros8# ping 10.3.8.3 count 1
PING 10.3.8.3 56 data bytes
64 bytes from 10.3.8.3: icmp_seq=1 ttl=64 time=1.36ms.

—- 10.3.8.3 PING Statistics —-
1 packet transmitted, 1 packet received, 0.00% packet loss
round-trip min = 1.36ms, avg = 1.36ms, max = 1.36ms, stddev = 0.000ms

Boom, super awesome.  I really like these bridges, they’re simple enough to install and work with.  What we have done is create two bridges, connected each VSR to the VX and then bridged these two host bridges together with sr3_sr8 on the VX.  Note the VX has no bridge for sros3_vx2 or sros3_vx1

BTW the user guide is really, really good. See it here cumulus_ug