RE: 802.17 RPR and L2 Ethernet interoperablity (Ethernet over RPR)


I think this is pretty provider-specific. However, we are doing this
right now with a particular vendor using their flavor of RPR. The ring
uses Q in Q tunneling in the core and all switches communicate directly
to one another using .1Q encapsulated frames.


From: [] On Behalf

Sent: Tuesday, July 06, 2004 11:50 AM
Subject: 802.17 RPR and L2 Ethernet interoperablity (Ethernet over



This is probably a fairly simply question, I'm probably just not quite
groking the layers involved here.

If I had the following setup:

Endstation A -- Switch A === RPR Ring === Switch B -- Endstation B

could there be a VLAN setup such that Endstations A and B are both in


and can communicate as if they are on the same LAN segment? (And I


natively. ie. not using an MPLS VPN). ie. Will the switches involved
tranlate the different framing formats in use? Is this vendor


Thanks for the reply. Pretty much everyone has told me that it's vendor
specific, although the implementation mentioned below sounds nice. Any
chance of naming that vendor?

One question about this, the Q-in-Q tunnelling would have to take place on
the switch connected to the ring - what happens if the packet has already
been placed in a dot1Q tunnel? I haven't really worked much with dot1Q
tunneling - are their any know problems with extra tags? (aside from MTU
issues, but I imagine most rings will support at least 9bytes)


Most switches will only see the outer tag and will thus be transparent for
Q-in-Q:ed packets.

That was my worry - the definition of most. 99% of switches or 60%? This
isn't actually a standard is it, so I presume this behaviour is expected,
but not required?


The only way to make sure is to try, but with my (I guess) average insight
in ethernet headers I don't see how a double tagged packet would be
treated differently by a non Q-in-Q aware switch as long as there is no
MTU issue.