VSP4000 VLAN tagging

[sbilde]

Originally Posted by zakabog

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.

That's not the point.
I want the box to work in a predictable way in consistence with the settings configured.
What I observe here is an inconsistent behavior - the tag is removed even if the box is configured not to do so, and changing the setting makes no effect.
If that AutoPVID is the default behavior - Id like to have it documented in the first place, and it would be nice to know the mechanism. How exactly does the switch decide which traffic goes where? First packet on the port? First ARP? First broadcast? First with this particular source MAC?

For example, there are plenty networks out there with a router having several subinterfaces tagged and untagged on the same physical port with a single source MAC address. I can't predict the VSPs behavior if such a port is connected.

Before I understand all that I can't put the box in production because the real life scenarios are well beyond a simple laptop connectivity described here

[zakabog]

Yeah, documentation would be great but I no longer expect to find any. Everything I've ever learned on these things has from been scanning through any documentation I can find as well as lots of trial and error, the more you go through the process the more everything starts to make sense.

Basically in your config, untagged traffic is going to travel across the default VLAN (VLAN 50) for the port it's coming from. Since your second port is configured as a trunk port and carrying traffic from both 50 and 150, it passes along the untagged traffic since it's on the same Layer 2 network (VLAN 50). You didn't tag the traffic from your laptop so it's not dropping any tags, it's just passing along the traffic as it was given, as if you had a flat switch.

[sbilde]

Originally Posted by zakabog

Since your second port is configured as a trunk port and carrying traffic from both 50 and 150, it passes along the untagged traffic since it's on the same Layer 2 network (VLAN 50). You didn't tag the traffic from your laptop so it's not dropping any tags, it's just passing along the traffic as it was given, as if you had a flat switch.

I may be misunderstanding your explanation, but that's not how the 802.1q Ethernet switch works.
There are no untagged packets "inside" the switch. Every untagged packet received is tagged with a default VLAN (a.k.a. PVID) and treated accordingly.

The outgoing port may be a member of several VLANs, but only the default VLAN a.k.a. PVID can be either removed from the outgoing packet (Access Port) or left as it is (Trunk).
I configure the port _not_ to remove the PVID, the switch removes it instead hence the problem.

[zakabog]

When you did encapsulation dot1q did you specify the two ports? Have you tried that to see if it makes any difference? Are you absolutely certain your laptops NIC does not understannd 802.1q tagged frames? Is there any reason you want to go against the recommended practice of dropping untagged frames?

[sbilde]

Originally Posted by zakabog

When you did encapsulation dot1q did you specify the two ports?

The system won't allow you to assign more than one VLAN if the port is in Access mode, that answers the question. And the laptops - yes, as untagged as can be.

As for the rest - again, the problem is not the scheme itself, but the fact that a switch isn't working the way it is configured.

Thanks for confirming the same behavior on the other product!
I'll escalate it to Avaya itself.

[zakabog]

Check that 802.1q encapsulation is enabled on the two ports first -

encapsulation dot1q port 1/1-2

That should do it, otherwise it will behave exactly as it is currently.

[sbilde]

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
...

[zakabog]

Okay, wasn't aware that meant the dot1q encapsulation was on for the port, but reading through this -

https://downloads.avaya.com/css/P8/documents/100123976

it looks like with discard untagged frames disabled, the switch is just going to pass along the untagged traffic to any ports on the same VLAN without tagging it.

[sbilde]

Originally Posted by zakabog

it looks like with discard untagged frames disabled, the switch is just going to pass along the untagged traffic to any ports on the same VLAN without tagging it.

It seems to be about SMLT. Can you point the page please?

[zakabog]

Page 67, it was the most relevant documentation I could find.