layer 2 data link encapsulation

carl_townshend · ‎02-29-2008

Hi all, can anyone tell me when we go from a normal lan ethernet network, then cross over ppp, or frame relay networks, what happens to the original layer 2 ethernet frame, does it change ?

rgodden · ‎02-29-2008

the ethernet frame will terminate on the router .

http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/introint.htm

carl_townshend · ‎02-29-2008

Hi

what do you mean terminate on the router ?

Jason Fraioli · ‎02-29-2008

He means that it will terminate at the device that connects to a Frame Relay, ATM, etc, network.

carl_townshend · ‎02-29-2008

hi

so when the ethernet frame goes out the say serial, or ppp, atm interface etc, whay happens to it ? does the ethernet frame get encapsualted or changed ?

Jason Fraioli · ‎02-29-2008

correct. With frame relay you might see PPP or HDLC encapsulations. With ATM you are going to see cells.

carl_townshend · ‎03-07-2008

so what changes? does the ethernet frame get converted to ppp frame? or is the ethernet frame still exsist but encapsulated in ppp, atm etc?

please explain

Joseph W. Doherty · ‎03-07-2008

The original Ethernet frame is discarded. Assuming you're doing IP, the L3 IP packet is encapsulated within the L2 frame for the media it's being sent across.