robcar's profile - activity

I think I misunderstood a concept above; the receiver keeps out-of-order packets in its buffer with or without SACK opti

Experimenting with No SACK Hello, I tried to disable SACK, just to see how the download of the same ISO file (see my pre

Ok, thanks for the clarifications. Can we say that SACK blocks are a sort of 'pre-acks', both to the receiver and the se

Hello, I was trying to understand how Fast Retransmission works. I downloaded an ISO image from a remote site and was analyzing the trace: sequence numbers, Dup ACKs, SACK and all that stuff. Lots of fun!

I saw how SACK's right edge grows, how another SACK buffer is added in the presence of a new 'TCP segment not captured' to the point where there can only be three buffers, then, when another 'TCP segment not captured' comes, the older seems to be flushed out.

Now, I saw the server eventually send the first Fast Retransmission, with the sequence number that the client had been desperately asking for over 200 ms (that's consistent with RTT). So far so good. But I've noticed something that I cannot explain.

The client was asking for the segment 19903603-19905043 (1440 bytes); the server finally sent that segment with the first Fast Retransmission, but then the client acknowledged 19915123. That's exactly seven segments more than the ones I expected. The SACK buffer, at that point, contained 21538003-21582643 21527923-21535123 21525043-21526483, so values that are out of range the ones that were acknowledged.

Now my question is: where did the client take the seven segments that it acknowledged?

Roberto

From RFC 2018: The data receiver SHOULD include as many distinct SACK blocks as possible in the SACK option. Note t

I have to add that, at the beginning of the Dup ACKs, the segment 19905043-19915123 was tracked in the client's SACK, be

Undertanding SACK and Fast Retransmission Hello, I was trying to understand how Fast Retransmission works. I downloaded

Undertanding SACK and Fast Retransmission Hello, I was trying to understand how Fast Retransmission works. I downloaded

Hello, Just out of curiosity, on a linux box (Ubuntu 18.04) what triggers a TCP Keep-Alive every 10 seconds? The value that I got from /proc/sys/net/ipv4/tcp_keepalive_intvl is 75 seconds. Thank you in advance. Roberto

While browsing via HTTPS (TLSv1.2) for instance to https://www.theguardian.com. I see occurrences of keepalives from my

TCP Keep-Alive on Linux - 10 seconds Hello, Just out of curiosity, on a linux box (Ubuntu 18.04) what triggers a TCP Kee