PPP or PPTP Multicast May Require a Manual Route Statement

ID: Q226124

The information in this article applies to:

Microsoft Windows 2000 Advanced Server
Microsoft Windows 2000 Professional
Microsoft Windows 2000 Server

SYMPTOMS

When you attempt to send multicast packets on a computer with multiple network connections, the multicast packets may not be sent on the expected network adapter.

CAUSE

In the following example, a computer has a network adapter with a Default Gateway setting of 209.43.128.138 (the first entry in the route table). Then, a Point-to-Point protocol (PPP) connection is made with a Default Gateway setting of 172.31.248.1 (the second entry). That route is added to the route table with a metric of 2, making it the default route. However, in the Multicast section (a network address of 224.0.0.0), all routes have a metric of 1. Therefore, no one adapter is designated as preferred.

Network address Netmask Gateway address Interface Metric

0.0.0.0 0.0.0.0 209.43.128.138 209.43.128.138 1

0.0.0.0 0.0.0.0 172.31.248.1 172.31.253.85 2

0.0.0.0 0.0.0.0 172.31.248.1 172.31.253.255 2

127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1

172.31.248.0 255.255.248.0 172.31.253.255 172.31.253.255 1

172.31.248.0 255.255.248.0 172.31.253.85 172.31.253.85 1

172.31.253.85 255.255.255.255 127.0.0.1 127.0.0.1 1

172.31.253.255 255.255.255.255 127.0.0.1 127.0.0.1 1

172.31.255.255 255.255.255.255 172.31.253.85 172.31.253.85 1

209.43.128.0 255.255.255.0 209.43.128.138 209.43.128.138 1

209.43.128.138 255.255.255.255 127.0.0.1 127.0.0.1 1

224.0.0.0 224.0.0.0 172.31.253.255 172.31.253.255 1

224.0.0.0 224.0.0.0 209.43.128.138 209.43.128.138 1

224.0.0.0 224.0.0.0 172.31.253.85 172.31.253.85 1

255.255.255.255 255.255.255.255 209.43.128.138 209.43.128.138 1

WORKAROUND

If you are sending multicast packets and they are not being sent on the correct adapter, use the route command to modify the routing table appropriately.

STATUS

This behavior is by design.

MORE INFORMATION

For assistance in using the route command, type route /? at a command prompt.

Additional query words:

Keywords : kbenv kbnetwork
Version : WINDOWS:2000
Platform : WINDOWS
Issue type : kbprb