Solutions

In SGOS 6.1.1.1, the ADN Core SG8100 sends DUP ACK to an edge ProxySG on ADN tunnel ports 3035 and 3037.

Solutions ID:    KB4206
Version:    2.0
Status:    Published
Published date:    12/13/2010
Updated:    09/06/2011
 

Problem Description

An SG8100 running SGOS versions 6.1.1.1 to 6.1.1.5 and serving as an ADN Core sends duplicate ACK message to the edge ProxySG on ADN tunnel ports 3035 and 3037. This behavior is not seen in Managed ADN deployments on port 3034 and 3036; it is also not an issue in SGOS 5.5.3.1.

This problem can be found in certain TCP network settings, ADN or SSL proxy implementation.

Example:

secure tunnel port 3037:
325    0.001000    2010-12-13 14:42:06.037999    10.78.56.154    10.78.56.163    3037    6564    TCP    66    hp-san-mgmt > 6564 [ACK] Seq=1261257170 Ack=3848804005 Win=65426 Len=0 TSV=273498564 TSER=273505059

dup 1:
326    0.000000    2010-12-13 14:42:06.037999    10.78.56.154    10.78.56.163    3037    6564    TCP    66    [TCP Dup ACK 325#1] hp-san-mgmt > 6564 [ACK] Seq=1261257170 Ack=3848804005 Win=65426 Len=0 TSV=273498564 TSER=273505059

dup 2
327    0.000000    2010-12-13 14:42:06.037999    10.78.56.154    10.78.56.163    3037    6564    TCP    66    [TCP Dup ACK 325#2] hp-san-mgmt > 6564 [ACK] Seq=1261257170 Ack=3848804005 Win=65426 Len=0 TSV=273498564 TSER=273505059

 

Resolution

This issue was fixed in 6.1.4.1 or later, 6.2.2.1 or later.

Root Casue:
While calculating the TCP window size to be advertised during connection establishment, TCP MAX window size is not being considered
.

Fix:
Window to be advertised is maxed at TCP MAXWIN during connection establishment.

 


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