Knowledge Base

NetBT Communication Slow on Multihomed Client

Article ID: 155986

Article Last Modified on 11/1/2006

Microsoft Windows NT Server 3.51

This article was previously published under Q155986

SYMPTOMS

When you communicate using NetBIOS over TCP/IP (NetBT) to a device that uses the second interface of a multihomed Windows NT client, the initial session establishment is slow.

CAUSE

This problem will only be seen in environments in which the subnets on both sides of the Windows NT client are not configured to communicate with each other.

RESOLUTION

Define a route, either per client or on the routers, to allow accessibility to both adapters on the computer running Windows NT Server.

MORE INFORMATION

NetBT first defines the IP address on the source packet of a three-way handshake using the IP address of the adapter that resolved the name. If this fails, NetBT uses the IP address of the second adapter. This can cause a delay of up to 50 seconds in the establishment of the connection.

NOTE: In Windows NT version 4.0 and Windows NT version 4.0 Service Pack 2, significant network connection enhancements have been added to improve connectivity for multi-homed computers. For detailed information, please see the following articles in the Microsoft Knowledge base:

ARTICLE ID: 161425
TITLE: WinNT 4.0 SP2 Multihomed Computer Connection Enhancement

ARTICLE ID: 166159
TITLE: NetBIOS Connections from a Multihomed Computer

Keywords: kbnetwork KB155986