What's a frame ?

[sukarabi]

Hello,

I had a problem with a packet crossing a network from point A to point B
The packet is crossing an Ethernet LAN, then go to a serial link throught a router and finally arrive on a remote LAN.
Not a CCIE level but still tricky question :
How many frame will encapsulate the packet during the trip from A to B ?

I answered 2 because a frame for me is something that encapsulate a packet on an ethernet basis (and it was the right choice for the test).
But how do we have to call a packet which is encapsulated via PPP or HDLC protocols ?

At this question is that possible to answer 3 ?

[lammle]

Yes, only on Ethernet do we use the term Frame.
However, I know what you are referring to and the answer to that question is 3. They should have used the word encapsulation as a generic term for how many times is the packet encapsulated from point A to B, but unfortantly they didn't. The correct answer of frames is two, the correct answer of encpasulation is 3, and that is the answer they are looking for. Wrong? Yes, but that's the way it is.
Todd

[sukarabi]

Thanks for your answer Mr lammle.
Yes I've to be carefull not to mix frame and encapsulation. Then I'm not going to loose point on this kind of question.

[lildeezul]

To make matters more confusing.. (sorry)

frame is a generic term for layer 2 ethernet, but as todd mention the correct asnwer of how many frames encapsulate the packet is three.

It will go to an ethernet frame to a HDLC/PPP/ATM/Frame-relay (depending on the serial encapuslation) to another ethernet frame..

Serial links do deals with frames, which is dependent of the encapulation type of the serial link.

For instance, if you configure the serial link with encapsulation hdlc. The layer 2 frame across that link will be an hdlc frame. (and since cisco added the type field in the hdlc frame, it is cisco proprietary)