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Some confusion with trunking

Colin Higgins
Occasional Contributor

Some confusion with trunking

Coming from a Cisco background, I find the HP implementation a bit counter-intuitive. It is my understanding that ports set up as trunks (in this case LACP trunks) should be "tagged" for ALL VLANs, including the "default" VLAN1.

But I have seen configurations in which to HP switches are connected and configured with 3 vlans. The default and two others. The client machines (workstations and servers) are assigned to vlans 2 & 3, and the trunk between the switches is tagged for these vlans.

However, the same trunk is not carrying tagged traffic for vlan1 (the default). Example:

vlan 1
name "DEFAULT_VLAN"
untagged B1-B4
ip address dhcp-bootp
no untagged A1-A24
no untagged C1-C24
exit

So here is my question ... If client machines are assigned to vlan 1 on both switches, should the trunk be tagged for these frames? In other words, should the above config look something like this:

vlan 1
name "DEFAULT_VLAN"
untagged B1-B4
ip address dhcp-bootp
no untagged A1-A24
no untagged C1-C24
tagged Trk1
exit

Any info would help greatly!

1 REPLY
JedE
Occasional Advisor

Re: Some confusion with trunking

Colin,

There are three possible options for Trk1:

vlan 1 - send no traffic on VLAN 1
name "DEFAULT_VLAN"
no untagged Trk1

vlan 1 - send untagged traffic on VLAN 1
name "DEFAULT_VLAN"
untagged Trk1

vlan 1 - send tagged traffic on VLAN 1
name "DEFAULT_VLAN"
tagged Trk1

In you case option 2 or option 3 is valid for you client systems and you chose depending on whether you have tagged VLAN 1 traffic on your client system,

Note the LACP trunk port members do not get listed individually in the VLAN tagging configuration.

Jed