Can soemone help me understand this p[lease! If I send data from NOde A to NOde B via various routers, does my Layer 3 address change(Network Header) or my layer 2 MAC address change in the frame? I got this question on the practice final and I couldnt understand it too well. Thanks and please forgivre my ignorance :-)
The layer 3 source and destination addresses will not change but the network headers will change (assuming IPv4) because the TTL will be decremented and the IPv4 header checksum recalculated at every hop. The layer 2 source and destination MAC addresses will change from hop to hop.
Cisco da Gama
The layer 3 source and destination addresses will not change but the network headers will change (assuming IPv4) because the TTL will be decremented and the IPv4 header checksum recalculated at every hop. The layer 2 source and destination MAC addresses will change from hop to hop.
Cisco da Gama
Thanks for that, I have my final examf for semester one tomorrow, fingers crossed ;-)
The question asked something like what will the router on the 1st hop be looking for- the correct answer I think is the next routers/hop Mac address and the destination IP address.
If NAT was used in your question, then layer 3 addresses definitely changed. But I will assume NAT wasn't involved since you didn't say so. (and just to re-iterate the first responder, MAC addresses change hop to hop)
HI- I have just read up on NAT, we havent covered that yet! I have only seen it when I am using Azureus- which keeps saying their maybe a NAT error...thanks for the advice...so to clarify - when the data leaves the node , when it gets to the first router the IP address of the destination stays the same, but the layer two addresses (source and destination) change.
I was getting confused when I read an analogy about IP addresses being your home address(which can change when you move house) whereas your MAC address is your name(which doesnt really change,unless you go to deedpoll ;_) ) .Tahnks again for your time chaps.
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