I lease a transparent ethernet connection between two different places from an ISP. The connection is given to me by having access to one port on one of their switches at one place, and another port at another switch at the other place. I've learned that they have this switched network where I have one VLAN id in it. It all works perfectly with untagged ethernet traffic between two hosts, one on each side of the link. (H1 - ISP - H2)
Now I need to know if it is possible for me to run a VLAN Trunk on this line. So instead of testing with the actual connection, I tried at the lab with four HP Procurve switches (1810G), but I was not successful. I set up one trunk between two switches (pair A). Then I set up another pair (pair B) of switches, the exact same way, but giving them a different trunk name. I could test both pairs by pinging from one host (H1) on one untagged port of one switch to another host (H2) on an untagged port on the other side.
H1 - A1 - A2 - H2 (ping ok)
H1 - B1 - B2 - H2 (ping ok)
Then I reconnected them in a line H1 - A1 - B1 - B2 - A2 - H2. I did not get a ping through.
I would like to have an answer whether this is possible or not, and if it is possible, how to set it up.