Microsoft KB Archive/216032

= Telnet 3270 Clients Experience Delay During Session Startup =

Article ID: 216032

Article Last Modified on 3/4/2004

-

APPLIES TO


 * Microsoft Host Integration Server 2000 Standard Edition
 * Microsoft SNA Server 3.0 Service Pack 4
 * Microsoft SNA Server 4.0

-



This article was previously published under Q216032



SYMPTOMS
Telnet 3270 clients may experience a long delay when starting sessions. This symptom is observed when a DNS Server is not available.



CAUSE
In the event a DNS Server is not available and Use Name Resolution is configured, a Telnet client will experience a delay of up to 50 seconds during session startup. The SNA Server expects a response from the DNS Server. SNA Server will delay the session until a timeout is reached.



RESOLUTION
The TN3270 Server Service contains a configuration option titled "Use Name Resolution". Use Name Resolution is found on the General tab of the TN3270 Properties dialog box. Use Name Resolution is required if access to TN3270 sessions is restricted through workstation names. It is not required if access to TN3270 sessions is restricted through a TCP/IP address or subnet. This option should be checked only if a domain name resolver is available on the network.



MORE INFORMATION
A Microsoft Network Monitor trace shows the Telnet client and SNA Server performing a three-way TCP handshake to initiate the session within 0.003 seconds. A delay in excess of 45 seconds occurred before the Telnet session was available to the client.

Here is an example of a three-way handshake to initiate a Telnet session.

Frame 1 TCP ....S., len:   4, seq:   4505720-4505723, ack:         0, win: 8192, src: 1147  dst:   23 (TELNET)  

Frame 2 TCP .A..S., len:   4, seq:   2489546-2489549, ack:   4505721, win:16064, src:   23 (TELNET)  dst: 1147 

Frame 3 TCP .A...., len:   0, seq:   4505721-4505721, ack:   2489547, win:16064, src: 1147  dst:   23 (TELNET)

Here is an example of the first two frames in the Telnet session. These frames will be delayed from the first three frames by 45 seconds or more. Frame 4 TELNET To Client With Port = 1147

Frame 5 TELNET To Server From Port = 1147

Additional query words: HIS 2000

Keywords: kbenv kbnetwork kbprb KB216032

-

[mailto:TECHNET@MICROSOFT.COM Send feedback to Microsoft]

© Microsoft Corporation. All rights reserved.