topic Voss Access/Trunk Port configuration in ExtremeSwitching (VSP/Fabric Engine)

Voss Access/Trunk Port configuration

Isaac001 — Mon, 27 May 2024 14:14:14 GMT

Hi Support,

I have gone through the extreme documentation but still the configuration between access port and trunk port in VOSS cli is really confusing to me.

For example:

vlan members 23 1/7 portmember I think refers to trunk port configuration on port 1/7

This article:https://extreme-networks.my.site.com/ExtrArticleDetail?an=000104947 Further adds to the configuration.

In the documentation, the there is also this Example:

For untagging the port in a VLAN:
#vlan create 12 type port-mstprstp 0 (Create VLAN and type)
#vlan mem 2/2 12 (Add it as a member)
#int gig 2/2
#encapsulation dot1q
#default-vlan-id port 2/2 12 (Specifying that vlan 12 is the default untagged vlan OR Native VLAN)
#untag-port-default-vlan (Specifying that vlan 12 will be used as untagged)
#exit

Kindly clarify with clear examples of the differences between access port and trunk port interface configuration in voss.

Thank you all!

Isaac.

Re: Voss Access/Trunk Port configuration

jeannette9728mi — Tue, 28 May 2024 08:55:16 GMT

To @Isaac001 ,

The confusion regarding access and trunk ports in Voss is understandable. Here's a breakdown to clarify the differences with configuration examples.
An access port allows traffic for a single VLAN (untagged traffic). Used for devices that only need to communicate on one network (e.g., computers, printers).
A trunk port carries traffic for multiple VLANs (tagged traffic). Used for devices that need to communicate with multiple networks (e.g., routers, switches in different VLANs).

! # Create VLAN 10 vlan create 10 type port-mstp-rstp 0 # Add interface GigabitEthernet 1/1 as a member of VLAN 10 vlan mem 1/1 10 # Configure GigabitEthernet 1/1 as an access port interface GigabitEthernet 1/1 no switchport mode trunk # Don't configure as trunk mode switchport mode access # Set mode to access default-vlan 10 # Set default VLAN to 10 (untagged traffic) !

This configuration creates VLAN 10 and adds GigabitEthernet 1/1 as a member. The interface is then configured as an access port with default-vlan 10, specifying that all untagged traffic on this port belongs to VLAN 10.

! # Create VLANs 20 and 30 vlan create 20 type port-mstp-rstp 0 vlan create 30 type port-mstp-rstp 0 # Configure GigabitEthernet 2/2 as a trunk port interface GigabitEthernet 2/2 switchport mode trunk # Set mode to trunk vlan member 20 30 # Add VLANs 20 and 30 as members (tagged traffic) !

This configuration creates VLANs 20 and 30. GigabitEthernet 2/2 is configured as a trunk port with switchport mode trunk. Then, VLANs 20 and 30 are explicitly added as members using vlan member, allowing tagged traffic for both VLANs on this port.

The main difference lies in the switchport mode and default-vlan commands.

Access Port no switchport mode trunk, default-vlan <vlan_id> (untagged traffic).
Trunk Port switchport mode trunk, vlan member <vlan_id1> <vlan_id2>... (tagged traffic).

Re: Voss Access/Trunk Port configuration

gfriedl — Tue, 28 May 2024 12:48:09 GMT

correct configuration examples, but not for Extreme VOSS 😉

there is no "switchport mode" command in VOSS.

instead one would need to use "no ecapsulation dot1q" for access port (no trunk), and "encapsulation dot1q" for trunk.

if one than adds such ports to vlan(s), an access port would "move" from current /previously assigned VLAn to the new.

A trunk port would just add this VLAN additionally to the existing VLANs on the trunk port.

the "default-vlan-id" prameter is only relevant (and configurable), when encaps dot1Q is enabled on port.

It is required, if one wants a dedicated untagged vlan on this trunk ; this requires "untag-port-default-vlan enable" for the interface to be used on this port. otherwise the default-vlan-id is irrelevant.

hope this help,

Re: Voss Access/Trunk Port configuration

WillyHe — Tue, 28 May 2024 13:09:08 GMT

Hello,

We are talking VOSS in this discussion

It is and will always be confusing people when talking about TRUNK.
First of all, what is a TRUNK?, a TRUNK is a group/collection/... of things.

For Cisco oriented people a TRUNK is a group of ports (LAG link aggregation).
For some others (EXTREME is one of them) they talk TRUNK in regards to a group of vlan's assigned to a port or an MLT (Multi Link Trunk).

So for some people a TRUNK is a group of vlan's, for others it is a group of ports.
First of all when starting discussing TRUNK's, agree in what you understand a TRUNK is.

btw,

The correct command to add a vlan to a port is "vlan members add 1111 1/25", so vlan first the the port.
The correct command to add a vlan to an MLT is "mlt 111 vlan 1111".
In the configuration it will be shown as port and MLT member, see below.

vlan create 1111 name "vlan_1111" type port-mstprstp 0
vlan mlt 1111 111
vlan members 1111 1/11 portmember

On an untagged or access port vlan info is removed from the outgoing packets.
On a tagged port, all vlan's can be tagged or all vlan's can be tagged except one which is untagged.

Re: Voss Access/Trunk Port configuration

Isaac001 — Tue, 28 May 2024 18:44:22 GMT

Hi @gfriedl

Thank you for your response. The information is still not that clear to me about the difference between access and trunk port in voss. So far from the replies I have noticed that trunk port should have encapsulation dot1q but access port no encapsulation dot1q. @WillyHe also mentioned that "The correct command to add a vlan to a port is "vlan members add 1111 1/25,so vlan first the port" Kindly comment on this for clarification.

I did a test configuration on a test VOSS switch and the output was surprising to me. Port 1/3 has default-vlan-id 10 Its supposed to be a trunk port so why does it have its default as 10?

Kindly see the configuration I did and output of show port vlan and snippets of running config. I would appreciate if you would share a sample standard configuration that would differentiate access and trunk ports if my is not that good. Thanks👍

===THE WAY I CONFIGURED===
!
vlan create 10 type port-mstprstp 0
vlan create 20 type port-mstprstp 0
!
int g1/1
no encapsulation dot1q
exit
!
int g1/2
no encapsulation dot1q
exit
!
vlan member 10 1/1
vlan member 20 1/2
!
int g1/3
encapsulation dot1q
exit
!

======SHOW PORT VLAN AND SECTION PORT RUNNING CONFIG=======

====================================================================================================
Port Vlans
====================================================================================================
PORT DISCARD DISCARD DEFAULT VLAN PORT UNTAG DYNAMIC UNTAG
NUM TAGGING TAGFRAM UNTAGFRAM VLANID IDS TYPE DEFVLAN VLANS VLANS
-----------------------------------------------------------------------------------------------------------
1/1 disable false false 10 10 normal disable P 10
1/2 disable false false 20 20 normal disable P 20
1/3 enable false false 10 10,20 normal disable P
#
# VLAN CONFIGURATION
vlan members remove 1 1/1-1/42,2/1-2/42 portmember
vlan create 10 type port-mstprstp 0
vlan members 10 1/1,1/3 portmember
vlan create 20 type port-mstprstp 0
vlan members 20 1/2-1/3 portmember
vlan create 4048 name "onboarding-vlan" type pvlan-mstprstp 0 secondary 4049
vlan i-sid 4048 15999999
#
# PORT CONFIGURATION - PHASE I
interface GigabitEthernet 1/3
encapsulation dot1q
exit
# PORT CONFIGURATION - PHASE II
interface GigabitEthernet 1/1
no shutdown
exit
interface GigabitEthernet 1/2
no shutdown
exit
interface GigabitEthernet 1/3
default-vlan-id 10
no shutdown
exit

Re: Voss Access/Trunk Port configuration

Isaac001 — Tue, 28 May 2024 18:51:28 GMT

Hi @jeannette9728mi

Thanks for your response, the explanation helped a lot as I am from a Cisco background and I think you were trying to respond in that way. However @gfriedl mentioned about the default-vlan-id and it threw me off a bit and the difference between vlan member 1/1 10 and vlan member add/remove 10 as mentioned by @WillyHe Otherwise thanks for shedding more light on it!👍 You can share more information about this?

Regards,

Isaac.

Regards,

Isaac.

Re: Voss Access/Trunk Port configuration

Isaac001 — Tue, 28 May 2024 18:55:41 GMT

Hi @WillyHe

Thanks for your response! Your explanation was heading somewhere until you mentioned MLT which is something am still grasping. So it threw me off your point. Kindly use straight forward example of regular port interface. Otherwise, thanks for shedding light on it!👍

Regards,

Isaac.

Re: Voss Access/Trunk Port configuration

WillyHe — Tue, 28 May 2024 19:58:00 GMT

Hello,

Are we using VOSS commands here???

The only way to configure a trunk or tagged port or an access or untagged port in VOSS is

VOSS_SWITCH-01:1(config-if)#interface gigabitEthernet 1/25
VOSS_SWITCH-01:1(config-if)#encapsulation dot1q
VOSS_SWITCH-01:1(config-if)#no encapsulation dot1q

Switchport, I think, is a Cisco command.

In VOSS (and also BOSS ERS), the default-vlan-id is always configured.
- When it is an access port then the default-vlan-id = automatically the to that port assigned vlan id and this cannot be changed.
- When it is a tagged or trunk port the default-vlan-id is also configured on the port but it has no meaning or effect unless untag-port-default-vlan is configured, then packets originating from the default-vlan-id are send out untagged (often used to tagg packets for an IP phone and untag packets for a PC connected behind the IP phone).

As an example I configured vlans 3000 3001 and 4000 on port 1/25 and configured vlan 4000 to be untaged.

SMC-MCN-003-01:1#show interfaces gigabitEthernet vlan 1/25
************************************************************************************
Command Execution Time: Tue May 28 21:48:55 2024 CEST
************************************************************************************
====================================================================================================
Port Vlans
====================================================================================================
PORT           DISCARD DISCARD    DEFAULT VLAN           PORT    UNTAG DYNAMIC UNTAG
NUM TAGGING TAGFRAM UNTAGFRAM VLANID   IDS            TYPE DEFVLAN VLANS VLANS
----------------------------------------------------------------------------------------------------
1/25 enable false false      4000    3000,3001,4000 normal enable P        4000
----------------------------------------------------------------------------------------------------
DYNAMIC VLAN Legend:
P=Protocol enabled.
SMC-MCN-003-01:1#

Re: Voss Access/Trunk Port configuration

WillyHe — Tue, 28 May 2024 20:10:09 GMT

In VOSS, and MLT is equal to etherchannel or LACP static configuration, it groups (trunks 😊) multiple ports in a Link-Aggregation-Group or Multi-Link-Trunk (so here we also talk about "trunk").

To have vlan's tagged/trunked on an MLT, this is enable/disabled on the MLT interface, not on the MLT member ports, the MLT is controlling the ports, at least for a "static" MLT configuration.
When LACP is enabled on an MLT then enable/disable tagging is done on port level.

Every switch OS has his way of doing things, most are similar but there are always (small 🙂) differences.

hope it helps clarifying
WillyHe

Re: Voss Access/Trunk Port configuration

gfriedl — Fri, 20 Dec 2024 13:51:47 GMT

your examples are fine. so 1/1 and 1/2 have tagging disabled, which means these are access (not trunk) ports.

Port 1/3 has encapsulation dot1q enabled, so is in trunk mode.

regarding PVID: if a trunk was never attached to any VLAN, the PVID is just 0. if it was assigned, it changes to this vlan and it stays so, when you add other VLANs to the trunk. you might chnage it anytime and this is necessary, when you want/must use untagged native VLANs, which on VOSS is defined by this PVID. To use untagged native vlan, you must specify it by PVID and also set "untag-port-default-vlan" on this port (or mlt).

Re: Voss Access/Trunk Port configuration

RosemaryDavis — Thu, 09 Oct 2025 11:26:47 GMT

Hi @Isaac001,

The confusion is understandable—VOSS handles VLAN membership a bit differently from other systems. Here’s a simple explanation.

Access Port (untagged port):
An access port carries traffic for only one VLAN, and all frames are sent and received untagged. Example:

vlan create 12 type port-mstprstp 0
vlan members 12 1/7
interface gig 1/7
encapsulation dot1q
default-vlan-id 1/7 12
untag-port-default-vlan
exit

This makes port 1/7 an untagged member of VLAN 12—ideal for endpoints like PCs or printers.

Trunk Port (tagged port):
A trunk port carries multiple VLANs, tagging traffic so connected devices can distinguish between them. Example:

vlan create 12,23 type port-mstprstp 0
vlan members 12,23 1/7 portmember
interface gig 1/7
encapsulation dot1q
default-vlan-id 1/7 12
exit

Here, port 1/7 is a trunk that tags VLAN 23 and others, while VLAN 12 is untagged (the native VLAN).

The key difference is that “portmember” adds a tagged VLAN, while without it the port is untagged. Each port can have one untagged VLAN but multiple tagged VLANs.

Best Regards,

EpyTV