SuSE Linux Enterprise Server OpenSSH 5.1p1 nagle issue?

[Jeremy Guthrie]

One node:  packet lengths > 1500 are TSO taking affect, if I turn off 
TSO, I see under normal conditions the appropriate size/sequence of packets.

Example of the connection performing correctly:
450   1.746243 SSH 2642 Encrypted response packet len=2576 clientend -> 
headend
451   1.746347 TCP 66 43269 > 22 [ACK] Seq=555192630 Ack=3074656266 
Win=16666 Len=0 TSval=1456827748 TSecr=798139682 headend -> clientend
452   1.746369 SSH 3930 Encrypted response packet len=3864 clientend -> 
headend
453   1.746386 TCP 66 43269 > 22 [ACK] Seq=555192630 Ack=3074657554 
Win=16666 Len=0 TSval=1456827748 TSecr=798139682 headend -> clientend
454   1.746396 TCP 66 43269 > 22 [ACK] Seq=555192630 Ack=3074654978 
Win=16666 Len=0 TSval=1456827748 TSecr=798139682 headend -> clientend
455   1.791951 TCP 66 43269 > 22 [ACK] Seq=555192630 Ack=3074660130 
Win=16666 Len=0 TSval=1456827760 TSecr=798139694 headend -> clientend
456   1.791973 SSH 5218 Encrypted response packet len=5152 clientend -> 
headend
457   1.792501 TCP 66 43269 > 22 [ACK] Seq=555192630 Ack=3074662706 
Win=16666 Len=0 TSval=1456827760 TSecr=798139694 headend -> clientend
458   1.792692 TCP 66 43269 > 22 [ACK] Seq=555192630 Ack=3074665282 
Win=16666 Len=0 TSval=1456827760 TSecr=798139694 headend -> clientend
459   1.792718 SSH 5218 Encrypted response packet len=5152 clientend -> 
headend
460   1.792741 TCP 66 43269 > 22 [ACK] Seq=555192630 Ack=3074667858 
Win=16666 Len=0 TSval=1456827760 TSecr=798139694 headend -> clientend
461   1.849577 TCP 66 43269 > 22 [ACK] Seq=555192630 Ack=3074670434 
Win=16666 Len=0 TSval=1456827774 TSecr=798139706 headend -> clientend
462   1.849600 SSH 5218 Encrypted response packet len=5152 clientend -> 
headend
463   1.849620 TCP 66 43269 > 22 [ACK] Seq=555192630 Ack=3074673010 
Win=16666 Len=0 TSval=1456827774 TSecr=798139706 headend -> clientend
464   1.849746 TCP 66 43269 > 22 [ACK] Seq=555192630 Ack=3074675586 
Win=16666 Len=0 TSval=1456827774 TSecr=798139706 headend -> clientend
465   1.849764 SSH 6506 Encrypted response packet len=6440 clientend -> 
headend

Example of the connection showing a ping-ponging effect using only 1288 
byte packets
1288  41.112341 TCP 66 43269 > 22 [ACK] Seq=555193638 Ack=3075980138 
Win=16666 Len=0 TSval=1456837590 TSecr=798149524 headend -> clientend
1289  41.386131 SSH 1354 Encrypted response packet len=1288 clientend -> 
headend
1290  41.432684 TCP 66 43269 > 22 [ACK] Seq=555193638 Ack=3075981426 
Win=16666 Len=0 TSval=1456837670 TSecr=798149604 headend -> clientend
1291  41.702157 SSH 1354 Encrypted response packet len=1288 clientend -> 
headend
1292  41.753245 TCP 66 43269 > 22 [ACK] Seq=555193638 Ack=3075982714 
Win=16666 Len=0 TSval=1456837750 TSecr=798149683 headend -> clientend
1293  42.022128 SSH 1354 Encrypted response packet len=1288 clientend -> 
headend



-- 
*Jeremy Guthrie*
Technical Architect - Orchestration | *CDW*
5520 Research Park | Madison, WI 53711
Phone: 608.298.1061 | Fax: 608.288.3007 | NOC: 608.298.1102 | Toll Free: 
866.202.1807