Subject: tcp mss question

From: bob packer <[email-masked]>
Date: Fri, 18 Jun 1999 10:10:28 -0700

Hello,

 A connection is made with receiver R who has sent a value 
 of large_mss for  its syn option and a sender S who has sent
 small_mss. 

 In the ensuing transfer, R sends time driven acks  rather than
 acking consecutive small_mss sized segments (given a window
 < 2*large_mss). 

 Clearly wrong per TCP-Illustrated but I don't find clarity in the
 RFCs. 1122 states that implementations should ack consecutive
 full sized segments and elsewhere describes full sized segments
 as the min of the received mss option and the local mtu - something
 not visible to the remote endpoint. Maybe I am missing something 
 here ?

 Anyone know of an authoratative reference on this point ?

 Thanks,
 bp

---

From: "Kevin Lahey" <[email-masked]>
Date: Fri, 18 Jun 1999 14:01:22 -0700

In message <[email-masked]>bob packer writes
> not visible to the remote endpoint. Maybe I am missing something 

With Path MTU Discovery, this can get tricky.  See RFC 2581.  Some
implementations (NetBSD) have started to ACK every second packet,
regardless of size; others (Linux) actually watch the size of the
incoming packets to attempt to determine the appropriate "full
size" for generating ACKs.

Enjoy,

Kevin Lahey
[email-masked]