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Connection Manager Route Management

Article ID: 291950 - View products that this article applies to.

This article was previously published under Q291950

SUMMARY

This article describes the Connection Manager, a versatile client dialer that has connection software which you can customize by using the Connection Manager Administration Kit (CMAK).

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Connecting a computer to a remote network through a dial-up or Virtual Private Networking (VPN) connection changes the routing table which controls the flow of packets. After this connection has been established, Microsoft remote access clients create a new default route pointing to the new connection. As a result, when a computer that is connected to one network establishes a new connection to another network, any packet which is not addressed to the immediate subnet will be routed through the dial-up connection.

One common situation where this behavior is encountered is during VPN connections across the Internet to a corporate network. When this connection is made, all connections to the Internet (for example, Microsoft Internet Explorer connections) are not possible without manual modifications to the routing table.

Connection Manager enables the deployment of such route table modifications through the use of a CmRoute connection action. This action uses the information associated with the default route entry in the routing table to identify the user interface associated with the new connection. CmRoute uses this information to create a new set of routes based on the routing table entries provided by a network administrator.

With CmRoute, there are two ways for the routing information to be specified:

Static routes can be supplied in a routing file located on the user's computer. This file is prepared by the network administrator as part of the Connection Manager profile.
Additional routes can be downloaded from a remote server at a predetermined Uniform Resource Locator (URL) location each time the client is connected. The additional route table (if any) is processed after the static route table (if any). Because the route file syntax supports both add and delete commands, these additional routes can either add to or replace entries that are defined in the Static Routes file.

The Routing Table Update dialog box, in CMAK, enables you to use the CmRoute connect action and a path to the route table which is distributed in the Connection Manager profile. This file contains the route entry modifications to be made to the client.

A Syntax of the Route Table

The Routing Table Update files are plain-text files that you can create and edit in any plain-text editor, such as, Microsoft Windows Notepad.

The syntax of the entries in the table is based on the command destination mask netmask gateway metric metric command.

In addition, where "default" is used in an entry, CmRoute can substitute the corresponding value obtained from the default route entry.

A route entry example:

add 192.168.1.0 mask 255.255.255.0 default metric default if default

An Example of Route Table Changes

Before the Connection Manager Connection Is Made:

This is the normal route table before any changes are made:

Windows IP Configuration


Ethernet adapter Local Area Connection 2:

        Connection-specific DNS Suffix  . :
        IP Address. . . . . . . . . . . . : 10.1.1.2
        Subnet Mask . . . . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . . . . : 10.1.1.3


===========================================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x2 ...00 c0 4f 86 d8 72 ...... 3Com 3C905TX-based Ethernet Adapter (Generic
===========================================================================
===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0         10.1.1.3        10.1.1.2       1
         10.1.1.0    255.255.255.0         10.1.1.2        10.1.1.2       1
         10.1.1.2  255.255.255.255        127.0.0.1       127.0.0.1       1
   10.255.255.255  255.255.255.255         10.1.1.2        10.1.1.2       1
        127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1       1
        224.0.0.0        240.0.0.0         10.1.1.2        10.1.1.2       1
  255.255.255.255  255.255.255.255         10.1.1.2        10.1.1.2       1
Default Gateway:          10.1.1.3
===========================================================================
Persistent Routes:
  None

After the Connection Manager Connection Is Made:

This example is after the Connection Manager connection is made (with the Use Default Gateway on Remote Network option enabled), but before CmRoute begins (the step where CmRoute obtains the gateway information):

Windows IP Configuration


Ethernet adapter Local Area Connection 2:

        Connection-specific DNS Suffix  . :
        IP Address. . . . . . . . . . . . : 10.1.1.2
        Subnet Mask . . . . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . . . . : 10.1.1.3

PPP adapter Virtual Private Connection:

        Connection-specific DNS Suffix  . :
        IP Address. . . . . . . . . . . . : 6.6.6.7
        Subnet Mask . . . . . . . . . . . : 255.255.255.255
        Default Gateway . . . . . . . . . : 6.6.6.7



===========================================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x2 ...00 c0 4f 86 d8 72 ...... 3Com 3C905TX-based Ethernet Adapter (Generic
0x100004 ...00 53 45 00 00 00 ...... WAN (PPP/SLIP) Interface
===========================================================================
===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0          6.6.6.7         6.6.6.7       1
          0.0.0.0          0.0.0.0         10.1.1.3        10.1.1.2       2
          6.6.6.7  255.255.255.255        127.0.0.1       127.0.0.1       1
    6.255.255.255  255.255.255.255          6.6.6.7         6.6.6.7       1
         10.1.1.0    255.255.255.0         10.1.1.2        10.1.1.2       1
         10.1.1.2  255.255.255.255        127.0.0.1       127.0.0.1       1
   10.255.255.255  255.255.255.255         10.1.1.2        10.1.1.2       1
        127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1       1
        224.0.0.0        240.0.0.0          6.6.6.7         6.6.6.7       1
        224.0.0.0        240.0.0.0         10.1.1.2        10.1.1.2       1
  255.255.255.255  255.255.255.255         10.1.1.2        10.1.1.2       1
Default Gateway:           6.6.6.7
===========================================================================
Persistent Routes:
  None

After CmRoute Has Run:

This example assumes that the following route add statement is in the CmRoute file:
add 192.168.1.0 mask 255.255.255.0 default metric default if default

===========================================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x2 ...00 c0 4f 86 d8 72 ...... 3Com 3C905TX-based Ethernet Adapter (Generic
0x100004 ...00 53 45 00 00 00 ...... WAN (PPP/SLIP) Interface
===========================================================================
===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0          6.6.6.7         6.6.6.7       1
          0.0.0.0          0.0.0.0         10.1.1.3        10.1.1.2       2
          6.6.6.7  255.255.255.255        127.0.0.1       127.0.0.1       1
    6.255.255.255  255.255.255.255          6.6.6.7         6.6.6.7       1
         10.1.1.0    255.255.255.0         10.1.1.2        10.1.1.2       1
         10.1.1.2  255.255.255.255        127.0.0.1       127.0.0.1       1
   10.255.255.255  255.255.255.255         10.1.1.2        10.1.1.2       1
      192.168.1.0    255.255.255.0          6.6.6.7         6.6.6.7       1
        127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1       1
        224.0.0.0        240.0.0.0          6.6.6.7         6.6.6.7       1
        224.0.0.0        240.0.0.0         10.1.1.2        10.1.1.2       1
  255.255.255.255  255.255.255.255         10.1.1.2        10.1.1.2       1
Default Gateway:           6.6.6.7
===========================================================================
Persistent Routes:
  None

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