I am investigating strange behavior of Microsoft Lync login problem. The problem is: "With same client PC(MAC address:c0:3f:d5:b0:a6:0a) and same login account, Lync login failed with IP add 10.212.76.119, while login successed with IP 10.212.76.73" I have two Wireshark's logs, one for problematic scenario and one for successful. I uploaded them here:
I can see that both in problematic & successful scenario there are series of "TCP Dup Ack" and "TCP Previous segment not captured", while in problematic scenario, no "TCP Retransmission" found. Could anybody explain why it could be the possible reason for this to happen? Thanks a lot in advance, Kevin asked 27 Sep '14, 22:09 hongtj |
One Answer:
Hi,
You can check MTU setting on all hops between client and server.It looks there are 6 hops by looking at TTL of server 10.232.211.23 which is 122.This is just assumption capture at both end will clear the picture. answered 28 Sep '14, 00:00 kishan pandey edited 28 Sep '14, 09:27 Jasper ♦♦ |
Quite exactly! client 119 is linked with server 23 with GRE tunnel. Server 23 is marked with AF31 for QOS.
So it seems what we should do next is to find out where along the path the ICMP message is blocked or where along the path the DF bit has been setted. Is that correct?
Thanks a lot, Kevin
The better method of handling this would be to reduce the MSS in the syn packets as the enter the GRE tunnel. https://www.google.de/?gws_rd=ssl#q=adjust-mss+gre