Encapsulation/Decapsulation question.

bbarrick

In the book I'm reading, the way it describes the process of a frame reaching a router from it's source and being passed on to it's next destination as if the source address and destination address is changed each time. So a packet leaving PC1 to R1 would have the address of PC1 as it's source and R1 as it's destination. Once it reaches R1, it makes it seem as though those addresses are dropped and the new source address is R1's and the new destination would be say, R2 before it then goes on to say PC2.

To me this doesn't really make a whole lot of sense, PC1 and PC2's addresses have to stay in the frame as the original source and final destination right?

pamccabe

bbarrick wrote: »

In the book I'm reading, the way it describes the process of a frame reaching a router from it's source and being passed on to it's next destination as if the source address and destination address is changed each time. So a packet leaving PC1 to R1 would have the address of PC1 as it's source and R1 as it's destination. Once it reaches R1, it makes it seem as though those addresses are dropped and the new source address is R1's and the new destination would be say, R2 before it then goes on to say PC2.

To me this doesn't really make a whole lot of sense, PC1 and PC2's addresses have to stay in the frame as the original source and final destination right?

Correct, the Layer 3 address would not change. The Layer 2, Ethernet addresses, would change. The router would strip the packet of the frames and then put new frames on with new source and destination Layer 2 addresses. Then forward the packet on.