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-   -   VSP4000 VLAN tagging (http://support.avaya.com/forums/showthread.php?t=6649)

sbilde 06-18-2015 10:49 AM

VSP4000 VLAN tagging
 
I'm testing various VLAN modes on VSP400 and have difficulties making a "trunk" port _not_ to strip the Default VLAN tag from outgoing packets.

Testbed:
There is a single VSP4450 rel 4.1 and two laptops with IPs 10.1.1.1/8 and 10.1.1.2/8 connected to 1/1 and 1/2

First surprise is that there is almost nothing on how to configure VLANs on a port in the most recent doc collection or anywhere else.
There seem to be two commands: encapsulation dot1q and vlan tagging tagall to switch between Trunk and Access modes.

Anyway, ports are trunks now, untag default VLAN is disabled.

Code:

VSP-4450GSX-PWR+:1(config)#sh interfaces gigabitEthernet vlan

================================================================================
                                  Port Vlans
================================================================================
PORT          DISCARD DISCARD  DEFAULT VLAN        PORT    UNTAG    DYNAMIC
NUM  TAGGING TAGFRAM UNTAGFRAM VLANID  IDS          TYPE    DEFVLAN  VLANS
--------------------------------------------------------------------------------
1/1  enable  false  false    50      50,150      normal  disable  P
1/2  enable  false  false    50      50,150      normal  disable  P
1/3  disable false  false    1      1            normal  disable  P
1/4  disable false  false    1      1            normal  disable  P
...

There shall be no ping between 1/1 and 1/2 since all the incoming packets are tagged with PVID and all the outgoing packets shall be tagged as well.
Yet the ping continues.
Enabling/disabling untag-port-default-vlan makes no difference.

Assumptions?

zakabog 06-18-2015 02:37 PM

I'm not quite sure what you're doing but if you build a trunk port it's not going to tag the VLANs, you're going to be able to ping between port 1 and port 2 because the VLANs exist on both ports. Are you sure you need trunk ports and not access ports?

sbilde 06-18-2015 02:44 PM

Quote:

Originally Posted by zakabog
if you build a trunk port it's not going to tag the VLANs, you're going to be able to ping between port 1 and port 2 because the VLANs exist on both ports.

Did you mean "Access port"? On trunk port I'm expecting all the outgoing traffic to be tagged - and that' exactly what's not happening.

I keep investigating and it turns out that two ports with identical settings in the same VLAN are able to pass both tagged and untagged packets depending on what kind of host is connected (I have a Laptop and a Cisco3750 as hosts, untagged and tagged correspondingly).

It all looks and works like an AutoPVID feature, only there shall be no AutoPVID on the VSP platform and there is no way to disable it.
Weird.

zakabog 06-18-2015 02:46 PM

I'm sorry, I mant to say it IS going to tag the VLANs but since the VLANs exist on both ports and you're using a subnet that overlaps, there is nothing keeping the two networks from communicating.

sbilde 06-18-2015 02:49 PM

Quote:

Originally Posted by zakabog (Post 18100)
I'm sorry, I mant to say it IS going to tag the VLANs but since the VLANs exist on both ports and you're using a subnet that overlaps, there is nothing keeping the two networks from communicating.

Well, a laptop doesn't understand tagged traffic. Therefore if a port sends tagged traffic a laptop won't be able to read it and the ping stops.

zakabog 06-18-2015 03:01 PM

Do you have the VSP set to discard untagged frames on those two ports?

sbilde 06-18-2015 03:22 PM

Quote:

Originally Posted by zakabog (Post 18102)
Do you have the VSP set to discard untagged frames on those two ports?

Nope, because they shall not _send_ untagged frames in the first place with this configuration.
It is explicitly configured NOT to untag the default VLAN.

zakabog 06-18-2015 03:36 PM

I don't have a VSP 4000 on my desk to test this with but looking at your config it seems like everything is working exactly as programmed. The port is tagging your untagged frames and the responses come back untagged because they were sent untagged. It looks like you need to enable discard untagged frames and do a test, or just start a wireshark capture and look for the tags..

sbilde 06-18-2015 03:45 PM

Quote:

Originally Posted by zakabog (Post 18104)
looking at your config it seems like everything is working exactly as programmed. The port is tagging your untagged frames and the responses come back untagged because they were sent untagged.

Not exactly as programmed. I program it NOT to remove the PVID tag yet it removes the tag anyway.

I don't want the box to make tag/untag decision based on some previous packets (auto-PVID), I want to explicitly program it NOT to untag the PVID and be sure it won't change its mind.

zakabog 06-18-2015 04:03 PM

What exactly is your end goal? If you want the laptop to not receive ping replies then you'll need to drop untagged frames. The switch isn't untagging your traffic, your laptop is never tagging the traffic to begin with. I just did a test here with an ERS 3500 which isn't exactly the same but a lot of the configuration is similar as the VSP is built upon the ERS platform. If I have a tagged port and I send untagged frames without filtering, I get a reply. If I filter untagged frames then I only receive a reply when I set the VLAN ID on my NIC to match the VLAN of the trunk port.


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