Looking briefly at a TCP transmission-related youtube video: https://www.youtube.com/watch?v=GfpThGUvbrM, I see that 'ACK's are sent per hop?

Is this the case of all TCP transmissions? Are there significant performance benefits of buffering TCP information per 'hop' vs conceptually sending packets to a destination and waiting for 'ACK's from that destination? (i.e. NOT buffering TCP packets on intermediary devices)?

Is it because this would greatly increase the number of 'dropped' packets? (I assume this would be the case at least...)


The ACKs go end-to-end in TCP transmission, not per hop. In the video you linked to, the arrows just are indicative of direction.

In a classical IP network (ie no firewalls or NAT), the intervening routers don't even look at the contents of the packets, they just forward them according to the IP header. (NAT and security processes only look deeper for determining things are safe/good/translatable as appropriate.) The internet protocol is designed to have the smallest possible per-hop load for the individual packets. Remember that one packet might take a completely different route to the next packet, and an intervening router holds no state to remember that it's seen part of this TCP stream before.

  • Thank you - glad I checked. I guess considering that I know that tcp packets may be sent separate routes that this should have been obvious! – Zach Smith Sep 19 '18 at 8:43

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