Optical Networking Layer 2

[michaeljmorris]

I was having a discussion today about Global IP networks from AT&T, WorldCom, etc that are moving to the "IP+Optical" standard. From what I understand it fiber optic cable, MPLS and IP (OSPF, BGP, etc).

My question is what is the Layer 2 technology? I may be thinking of this from a TDM world (I work on several enterprise networks), but if it's not Ethernet everywhere (they're getting there), what is the Layer 2 technology the breaks the packets into frames and frames the 1's and 0's from the fiber network ?

I've read about RPR and DPT. Are these the Layer2 encapsulation used?

Thanks.

[m.prouty]

Check out this white paper on the cisco page. It should shed some light on the layer 2 as well as layer 2 and layer 3 merging.

http://www.cisco.com/warp/public/cc/pd/rt/12000/tech/posdh_wp.htm

HTH

M.

[backnaction]

The layer 2 technology they are touting about is SONET.....just another 're-hash' of an existing technology.

[lcsaszar]

RPR and SRP (formerly called DPT) are Layer 2 MAC encapsulation protocols providing multiple access over Sonet. They virtually emulate a LAN environment.

On point-to-point Sonet links the choice of Layer 2 encapsulation is HDLC, PPP, Frame Relay. ATM is a special case, not fitting in the OSI layered model. ATM can also be a transport over Sonet, which is always Layer 1.