new firmware, how to do trunks now?

This thread has been locked for further replies. You can start a new thread to share your ideas or ask questions.

new firmware, how to do trunks now?

This thread has been locked for further replies. You can start a new thread to share your ideas or ask questions.
new firmware, how to do trunks now?
new firmware, how to do trunks now?
2020-08-06 15:17:36 - last edited 2021-01-23 18:45:33
Hardware Version: V2
Firmware Version: 20190516 Rel.33426

I just purchased a T2600G-18TS and I'm pretty new to configuring switches still. I see tp-link removed switch port mode trunk.

 

I did search the forums, but I'm still confused on what I read. Only thing I saw was to tag each vlan on a port you want to pass. Does this mean there's no way to pass all vlans?

 

I also came up with this solution, but I'm not sure if it does what I think it does.

 

interface gigabitEthernet 1/0/1

switchport general allowed vlan all

 

Will that do what mode trunk did?

 

Thanks!

 

  0      
  0      
#1
Options
1 Accepted Solution
Re:new firmware, how to do trunks now?-Solution
2020-08-08 08:58:51 - last edited 2021-01-23 18:45:33

 

Yannie wrote

The difference between the General port and Trunk port is when forwarding frames, General port decides to forward the frames with or without tag according to the egress rule, while Trunk port forwards the frames with tags.

 

This notation of TRUNK and GENERAL ports was once introduced by Cisco to control the egress behavior of frames being internally forwarded to (arriving on) a trunk port.

 

During forwarding operations all frames always have a tag. I give you an example: Assume an untagged frame enters the switch on port 1 and gets tagged with VLAN ID 100 due to the port's PVID=100. The frame is being forwarded as a tagged frame internally and arrives on port 8 which is member of several VLANs including VLAN 100 and also has a PVID of 100.

 

Question now is: how should the switch handle this frame on egress on port 8?
The ancient solution to answer this question was the introduction of two trunk types: TRUNK and GENERAL.

 

  • With a TRUNK port, the tag 100 got removed on egress on port 8 since the port's PVID is 100.
  • With a GENERAL port, the tag 100 was left intact on egress on port 8 even due its PVID is 100.

 

Thus, for a TRUNK port its Port VLAN defined by the Port VLAN ID (PVID) determined whether to remove a tag on egress (not on forwarding operations as some FAQs suggest).

 

However, this can be much better controlled by marking the port as tagged or untagged member of this VLAN 100.

 

Nowadays, TP-Link switches always use trunk ports which behave like former GENERAL ports used in TP-Link firmwares two generations back. The old switches are EoL meanwhile. The GENERAL / TRUNK port types have been removed many years ago in 2nd generation firmwares already, it has not been changed in the 3rd generation firmwares (the latest generation with the brand-new web UI).

 

Don't let you confuse, there are no GENERAL ports anymore, albeit you still find this ancient port type in the CLI commands. It will force admins who were used to this old notation to use (former) GENERAL ports for trunks.

 

But those ports are trunk ports as per definition (trunk = port which is member of two or more VLANs). Whether tags are removed from a trunk port on egress is decided by the tagged/untagged attribute. Note that this attribute is related to both directions, ingress and egress.

 

The consequence of this change is that you now can create asymmetric VLANs where a port can be an untagged member of two or more VLANs and tags can be removed from frames in both VLANs on egress. This was not possible with so-called TRUNK ports in older firmwares.

 

༺ 0100 1101 0010 10ཏ1 0010 0110 1010 1110 ༻
Recommended Solution
  2  
  2  
#5
Options
4 Reply
Re:new firmware, how to do trunks now?
2020-08-07 22:41:12 - last edited 2020-08-07 22:41:46

@gregf, assigning a port membership in two or more VLANs makes it what usually is called a »trunk«. Note that the standard doesn't define those terms (trunk port, access port), they are just a common notation and they are even used inconsistently.

 

So, to answer your question: if a port is assigned to all VLANs, it becomes a trunk port.

༺ 0100 1101 0010 10ཏ1 0010 0110 1010 1110 ༻
  0  
  0  
#2
Options
Re:new firmware, how to do trunks now?
2020-08-07 23:02:07

@R1D2 Thank you.

  0  
  0  
#3
Options
Re:new firmware, how to do trunks now?
2020-08-08 05:32:57

@gregf 

 

Hi,

 

I see tp-link removed switch port mode trunk.

 

 

TP-link switch now supports the General link type only, which actually simplify the VLAN configuration.

 

Similar to Trunk port, General port can also belong to multiple VLANs. The difference between the General port and Trunk port is when forwarding frames, General port decides to forward the frames with or without tag according to the egress rule, while Trunk port forwards the frames with tags. So General port can become Trunk port when the egress rule is configured as tag.

 

Hope that helps. Good Luck!

  0  
  0  
#4
Options
Re:new firmware, how to do trunks now?-Solution
2020-08-08 08:58:51 - last edited 2021-01-23 18:45:33

 

Yannie wrote

The difference between the General port and Trunk port is when forwarding frames, General port decides to forward the frames with or without tag according to the egress rule, while Trunk port forwards the frames with tags.

 

This notation of TRUNK and GENERAL ports was once introduced by Cisco to control the egress behavior of frames being internally forwarded to (arriving on) a trunk port.

 

During forwarding operations all frames always have a tag. I give you an example: Assume an untagged frame enters the switch on port 1 and gets tagged with VLAN ID 100 due to the port's PVID=100. The frame is being forwarded as a tagged frame internally and arrives on port 8 which is member of several VLANs including VLAN 100 and also has a PVID of 100.

 

Question now is: how should the switch handle this frame on egress on port 8?
The ancient solution to answer this question was the introduction of two trunk types: TRUNK and GENERAL.

 

  • With a TRUNK port, the tag 100 got removed on egress on port 8 since the port's PVID is 100.
  • With a GENERAL port, the tag 100 was left intact on egress on port 8 even due its PVID is 100.

 

Thus, for a TRUNK port its Port VLAN defined by the Port VLAN ID (PVID) determined whether to remove a tag on egress (not on forwarding operations as some FAQs suggest).

 

However, this can be much better controlled by marking the port as tagged or untagged member of this VLAN 100.

 

Nowadays, TP-Link switches always use trunk ports which behave like former GENERAL ports used in TP-Link firmwares two generations back. The old switches are EoL meanwhile. The GENERAL / TRUNK port types have been removed many years ago in 2nd generation firmwares already, it has not been changed in the 3rd generation firmwares (the latest generation with the brand-new web UI).

 

Don't let you confuse, there are no GENERAL ports anymore, albeit you still find this ancient port type in the CLI commands. It will force admins who were used to this old notation to use (former) GENERAL ports for trunks.

 

But those ports are trunk ports as per definition (trunk = port which is member of two or more VLANs). Whether tags are removed from a trunk port on egress is decided by the tagged/untagged attribute. Note that this attribute is related to both directions, ingress and egress.

 

The consequence of this change is that you now can create asymmetric VLANs where a port can be an untagged member of two or more VLANs and tags can be removed from frames in both VLANs on egress. This was not possible with so-called TRUNK ports in older firmwares.

 

༺ 0100 1101 0010 10ཏ1 0010 0110 1010 1110 ༻
Recommended Solution
  2  
  2  
#5
Options

Information

Helpful: 0

Views: 1054

Replies: 4

Related Articles