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Q235489: How to Use RIP over RRAS Demand-Dial and VPN Connections

Article: Q235489
Product(s): Microsoft Windows NT
Version(s): winnt:4.0
Operating System(s): 
Keyword(s): kbenv
Last Modified: 10-AUG-2001

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The information in this article applies to:

- Microsoft Windows NT Server version 4.0 
- Microsoft Routing and Remote Access Service Update for Windows NT Server version 4.0 
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SUMMARY
=======

This article describes how to implement Routing Information Protocol (RIP) over
Routing and Remote Access Service (RRAS) Dial On Demand (DOD) connections. The
implementation of this protocol is the same for both direct-dial modem
connections and Virtual Private Network (VPN) connections over the Internet.

MORE INFORMATION
================

The information in this article applies to both direct connections and VPN
connections. In the following examples, RRAS is used to provide LAN-to-LAN
routing:

  Example Direct-Dial Modem Connection

  Lclient           L-RRAS === Modem() === R-RRAS           Rclient
   |      IP      |                        |      IP      |
    --------------                          --------------

  Example VPN Connection

  Lclient           L-RRAS ===== VPN ===== R-RRAS           Rclient
   |      IP      |  |      Internet     |  |      IP      |
    --------------    -------------------    --------------

NOTE: For the purposes of this article, a DOD connection refers to either a
direct-dial connection using a modem or a VPN tunnel connection over the
Internet. Because RIP does not distinguish between connectivity methods, both
are used in the same manner.

Before you configure RIP for LAN-to-LAN routing (as in the two examples above),
do the following:

1. Make sure your DOD connections dial and connect successfully.
  This is true for both modem and VPN connections. You can add temporary static
  routes to the RRAS servers to test routing capabilities, but you should
  remove them after testing. RIP does not work if the DOD connections do not
  connect.

2. Adding RIP from within the RRAS Management Console:

  a. Start the RRAS Administration tool.

  b. In the IP Routing section, right-click Summary, and then click Add Routing
     Protocol.

  c. Click "RIP version 2 for Internet Protocol", and then click OK.

During RIP installation, you can configure event logging on the General tab and
security parameters on the Security tab. You should leave these set to their
defaults during installation and change them after RIP is installed.

After you install RIP, the "RIP for Internet Protocol" icon is displayed in the
IP Routing section of the RRAS Administration tool. Right-click "RIP for
Internet Protocol", and then click Add. Click the DOD interface you are using
between the two RRAS servers (you need to do this on both RRAS servers). Add the
interfaces that RIP uses in this section (usually the DOD interfaces and the LAN
side interfaces). In the VPN example above, it is not necessary to add the
interface that connects to the Internet unless there are other compelling
reasons to do so.

When you add an interface, you can change the RIP configuration. Four tabs are
available: General, Security, Neighbors, and Advanced. Typically, you can leave
these settings at their default values and RIP functions properly. You can make
any changes to RIP after you initially configure the added interfaces. The
General tab is described in more detail below. For more information about these
settings, refer to the RRAS Administrators Guide.

On the General tab, you can click "Operation mode" and choose one of the
following options to indicate whether the interface is treated as a persistent
connection or DOD connection:

- Periodic Mode: Indicates that RIP broadcasts or multicasts are sent over the
  interface based on the periodic rate (the default setting is every 30
  seconds).

- Auto-Static Mode: Indicates that periodic updates are not sent over the
  interface and that manual updates by an administrator are necessary.

NOTE: By default, network adapters use Periodic mode, and DOD connections use
Auto-Static mode, but you can specify the appropriate mode for your
environment.

At this point, even though RIP is installed, DOD connections do not dial and
cannot be forced to dial. Even if you configure the DOD connection to use
Periodic mode, the connection does not dial. However, if you manually dial the
connection and Periodic mode is enabled, the connection does not disconnect
after connected. For additional information, click the article number below to
view the article in the Microsoft Knowledge Base:

  Q235492 RIP and OSPF Do Not Start Dial On Demand Connections

To force RIP to start a DOD connection, make sure that a route entry exists that
forces the DOD connection to dial. You can do this using the appropriate
method:

Using Auto-Static Mode
----------------------

On each RRAS server in the IP Routing section, right-click the DOD (either the
modem or VPN interface), and then click Update Routes. After the connection is
made, the DOD copies over the routes normally learned by RIP as static routes in
the route table. After this task is finished, the DOD is forced to dial back
based on the routing table (even if the DOD drops because of inactivity). You
must do this on each side, unless only one side is required to dial. These
auto-static updates are not dynamic. If there are changes to a network, then you
must select the Update Routes option again to update the static routes in the
route table of the RRAS server. You may also need to stop and restart the RRAS
server to complete the configuration changes.

Using Periodic Mode
-------------------

Add a default gateway static route that points to the DOD or specific network
routes that point to the DOD. You need to do this on each side for routing
purposes. In this example, you must manually add the static routes and RIP
learned routes are placed in the routing table after the DOD is connected. If
you add static routes using Periodic mode, you should also do the following:

1. Give static routes a higher metric than routes that are learned by RIP. This
  process is sometimes a matter of trial and error, but the desired result is
  that RIP learned routes have a better metric than the static routes.

2. Change the preference level of RIP routes:

  a. Start the RRAS Administration tool.

  b. In the IP Routing section, right-click Summary, and then click "Configure
     IP parameters".

  c. On the Preference Levels tab, click "RIP Version 2 for Internet Protocol",
     and change the preference level from 4 to 1 (the preference level itself
     is not as important as the fact that you should give RIP routes more
     preference than static routes).

Additional query words:

======================================================================
Keywords          : kbenv 
Technology        : kbWinNTsearch kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbAudDeveloper kbRRASNTSearch kbRRASNT400
Version           : winnt:4.0
Issue type        : kbinfo

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