Help with a question

loboernesto

hi guys,
I need some help with the language...
There's this question in the "do i know this already?" 5th chapter of the Intro cert guide by cisco press.

the question is asking me for the largest entities that make it from pc1 to pc2. there are several routers between Pc1 and pc2 and it gives as options the different layer's PDUs (I'm not sure whether tt's allowed to post this kind of question or not but I'm sure all most everyone will have a copy of the book to check for the question I'm saying)

The thing is: I can probably work out the solution but due to my poor english I can't understand what the question is asking! what does it mean by entities?? This is the type of question that really get me. Sometimes I don't understand what they mean or worse I misunderstand!!

Thanks.

james_

I read it as though entities meaning the type of unit passed across the network. As you probably know:

Layer 1 - Bits
Layer 2 - Frames
Layer 3 - Packets
Layer 4 - Segments

Each of these is an entity, and can be represented as a PDU, ie frames can be called a L2PDU - Layer 2 Protocol Data Unit. Now, as Routers are referenced in this particular question, the answer has to be......

loboernesto

Thank james, I was thinking on that question.
I know routers will work with packets or L3PDUs, but the question mentioned the "largest" entities that would make it... So I was thinking frames are physically larger than any other PDU since they have all the headers from the other layers, I mean: Segments will be only the data plus a transport layer header but at the time the segment reaches the layer 2 it will have network layer header plus data-link header and trailer making the size of it larger than the the original segment or even packet. But obviously I didn't get the question. Thank for you answer. I hope I don't come across many of this question!!
Cheers

EdTheLad

The largest entity will be a packet.The pc will send out a frame which will be received by the router, unencapsulated and forwarded as a new frame.So the
original frame does not make it from pc1 to pc2.