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HP Tagging vs Cisco Trunking Updated

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HP Tagging vs Cisco Trunking Updated

Hi All

I am about to do a major upgrade next week and replace our core cisco 3750 stack with a 5400 series core.

Our Edge network is a combo of approx 10 HP 2600series and 15 x cisco 2950 switches.

My Question is rather simple. I know HP switch config and setup and the tagging for the vlans on the HP side. But Im not very comfortable with the cisco side. I assume on the cisco I make the 'user' ports static on the vlan, and on the uplinks I trunk using 802.1q trunk but Im not really sure of the commands to do this, and then to allow only selected vlans on these trunks.

I guess im looking for a step by step dummy guide to setting this up on the cisco 2950.

What I want to do is very simple.
E.g. Allow a Wireless AP point connected to the cisco 2950 to work which uses vlan 40, 42, and 44. The static ports are on vlan 16. The HP uplink is untagged is default vlan, tagged 40, 42,44 and 16. So I need to setup the cisco so that the uplink port anf the Wireless Access Port is 'tagged' for those subnets.

Sorry for the Dual Post. I stuffed up.

Thanks in advance.

Mohieddin Kharnoub
Honored Contributor

Re: HP Tagging vs Cisco Trunking Updated


On the Cisco switch and inside the interface that connects to the AP:

SW(config-if)#switchport mode trunk
SW(config-if)#switchport trunk allowed-vlan add 16,40,42,44

Check this:

Good Luck !!!
Science for Everyone
Chris Stave

Re: HP Tagging vs Cisco Trunking Updated


Pretty much what Mohieddin said, but I will add a little bit to it.
The one important difference between HP and Cisco 802.1Q implementation is that HP ports have the tagged and untagged ports explicitly defined, while at its most basic, Cisco ports are either in access mode or trunk mode. Access mode effectively has nothing tagged and one vlan untagged. Trunk mode by default has VLAN 1 traffic untagged and will pass ANY tagged traffic. You can change this behavior, limit the VLANS that it will work with, but by default,
Cisco(config-if)#switchport trunk encap dot1q
Cisco(config-if)#switchport mode trunk
will let EVERYTHING through -- so that would be the minimal configuration to get it to work.

If your default vlan is not VLAN 1 then you will need to use
switchport trunk native vlan xxx

This is the Cisco equivalent of having that VLAN untagged, but since the port is in Trunk mode it tags everything else. This is also useful if the management interface for the AP is not on VLAN 1.

Good luck! Hopefully I've been at least somewhat clear in my description above.

Re: HP Tagging vs Cisco Trunking Updated

Thankyou both for your reply.

After alot of trouble I got it working. My biggest problem was that althought I thought I had the vlans on the cisco switch (I would create them) they would not work. When I used cisco network assistant I coudl see inthe config that it remembered the old vlans and had not added the new one. So I needed to fix that.

I am definently a HP fan. So much easier to use!