# Waiting time in CSMA/CD doubt

I have a doubt regarding the time a particular node will wait after collision.

I am using numerical values here so that one can easily understand my doubt.

Suppose in a network, we have 2 nodes A and B with propagation delay of 225 bit times.

If A and B sense channel at the same time and find it idle, they both will collide and will sense collision at 225 bit times .

If we assume jamming signal as 48 bit and IFS time 96 bit time(standard ones), then both A and B will send jamming signal to all other nodes by 225 + 48 = 273 bit time.

Now I want to know whether channel is really idle by time 273 bit times and can A start sending after IFS time or the channel still contains B's transmission and A needs to wait for another 225 bit times (propagation delay) until B's last bit reaches A and channel is cleared?

• You'll find your problem easier to solve by drawing a timeline diagram; usually done vertically, two lines for two stations, diagonal lines for signals. You might care to edit your question to clarify what you meant at `225 + 45 = 273` – jonathanjo Dec 1 '17 at 15:21
• I am sorry. It's actually 48 and not 45. By the time 225 + 48, all nodes will receive the jamming signal. – Zephyr Dec 1 '17 at 15:44
• My only doubt is will A wait until B's last bit reaches A and the channel gets cleared or not . Because in the actual algorithm flow diagram of CSMA/CD, I didn't find any such thing. – Zephyr Dec 1 '17 at 15:55
• @jonathanjo Please check my edit for the diagram. – Zephyr Dec 1 '17 at 18:08
• Can someone answer this ? – Zephyr Jan 8 '18 at 18:11