[pox-dev] MPLS match and labels popping

[Murphy McCauley]

On Nov 8, 2015, at 8:04 AM, AMER <amer7777 at hotmail.com> wrote:

> Dear All
> 
> I would like to ask you about the following match commands and actions
> 
>        msg1 = nx.nx_flow_mod()
>        msg1.match = nx.nx_match()
>        msg1.match.eth_type = pkt.ethernet.MPLS_TYPE       
>        msg1.match.mpls_label = 50# host 1 10.0.0.1
>        msg1.actions.append(of.ofp_action_output(port = 1))
> 
> The above matches didn't work

I'd suggest trying to narrow down why it doesn't work.  If you remove the label match, do all MPLS packets go out port 1?  Have you used Wireshark or something to confirm that there are packets that you think should match with label 50?

It's also possible that some MPLS stuff just plain doesn't work with current/almost-current OVS, I suppose.  It was added to POX when MPLS support was pretty experimental...

> when I tested it in mininet 2.2.1, OvS 2.3.2 , POX is "POX 0.2.0 (carp)"

Carp is pretty old.  I have no memory of whether there are known problems with it.

> The push command is:
> 
>        msg = nx.nx_flow_mod()
>        msg.match.of_eth_src = "00:00:00:00:00:04"
>        msg.actions.append(nx.nx_action_push_mpls())
>        msg.actions.append(nx.nx_reg_load(dst=nx.OXM_OF_MPLS_LABEL, value=50))
>        msg.actions.append(of.ofp_action_output(port = 2))
>        core.openflow.sendToDPID(event.dpid, msg)
> 
> Also, when I tried to use pop command as the following I received the down error
> 
>        msg1 = nx.nx_flow_mod()
>        msg1.match = nx.nx_match()
>        msg1.match.eth_type = pkt.ethernet.MPLS_TYPE       
>        msg1.match.mpls_label = 50# host 1 10.0.0.1
>        msg1.actions.append(nx.nx_action_pop_mpls()) ######<-- POP
>        msg1.actions.append(of.ofp_action_output(port = 1))
> 
> The error is:
> 
> POX 0.2.0 (carp) / Copyright 2011-2013 James McCauley, et al.
> INFO:forwarding.l2_mid:Simple NX switch running.
> INFO:core:POX 0.2.0 (carp) is up.
> INFO:openflow.of_01:[00-00-00-00-00-02 1] connected
> INFO:forwarding.l2_mid:2 switches in path
> INFO:openflow.of_01:[00-00-00-00-00-01 2] connected
> INFO:forwarding.l2_mid:1 switches in path
> ERROR:core:Exception while handling OpenFlowNexus!ConnectionUp...
> Traceback (most recent call last):
>   File "/home/alghada/pox/pox/lib/revent/revent.py", line 231, in raiseEventNoErrors
>     return self.raiseEvent(event, *args, **kw)
>   File "/home/alghada/pox/pox/lib/revent/revent.py", line 278, in raiseEvent
>     rv = event._invoke(handler, *args, **kw)
>   File "/home/alghada/pox/pox/lib/revent/revent.py", line 156, in _invoke
>     return handler(self, *args, **kw)
>   File "/home/alghada/pox/pox/forwarding/l2_mid.py", line 110, in _handle_ConnectionUp
>     core.openflow.sendToDPID(event.dpid, msg1)
>   File "/home/alghada/pox/pox/openflow/__init__.py", line 353, in sendToDPID
>     self._connections[dpid].send(data)
>   File "/home/alghada/pox/pox/openflow/of_01.py", line 692, in send
>     data = data.pack()
>   File "/home/alghada/pox/pox/openflow/nicira.py", line 387, in pack
>     packed += i.pack()
>   File "/home/alghada/pox/pox/openflow/libopenflow_01.py", line 2036, in pack
>     body = self._pack_body()
>   File "/home/alghada/pox/pox/openflow/nicira.py", line 815, in _pack_body
>     p = struct.pack('!HHI', self.subtype, self.ethertype, 0) # 4 bytes pad
> error: cannot convert argument to integer

This one is very easy.  pop requires the new Ethertype to be given.

nx_action_pop_mpls(ethertype=0x0800) or something like that will be more likely to work (if the packet was IP).

> Any help is appreciated
> 
> Best regards,
> 
> Eng Amer Alghadhban
> COE
> SANS-GCFW
> CEH, SCNP, CCNA

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