HP 1810 switch - how to connect two VLANs within same subnet?

[Nikriaz]

I need to traverse two my own VLANs (ID 1 and 7) through the building's VLAN 2078 and 2079 those are tagged in one cable. Thus, I have to somehow connect 1 to 2078 and 7 to 2079 on the both ends of the building cable.

Can't wrap my mind how to achieve that. The only solution I have is to have tagged 2078 port, untag it to another port and physically connect it to the port on the same switch with untagged VLAN 1 (and the same with 2079 to 7). Not too elegant. I don't see an option to bridge two VLANs within the switch. Once time again, I do not need routing or any other L3 features between VLANs since there is a single, same subnet. 

Do I miss something? Please help.

[Jasoned32 · Accepted solution]

This is assuming you dont have to pass any other vlans through those ports. 

untag vlan 2078  and plug it into untag 1

untag vlan 2079 and plug it into untag 7

Its not elegant by any means and you will need to check spanning tree. Will the 1810 not let you create vlans 2078 and 2079?

[Nikriaz]

Finally I did it.  It works as advised. 

I changed VLAN ID from 7 to 2079 across my network to match my ID with external ID but did the trick with port-to-port cable for 1-to-2078 conversion because I didn't want to hurt my default VLAN 1. The obvious drawback is the loss of two ports in the switch but okay.

Many thanks for advice!