TUTORIAL: Windows Server 2008 IP routing configuration

Introduction
With Windows Server 2008, there are a number of changes to networking, routing and remote access. The most notable change is the omission of Open Shortest Path First (OSPF). I find that unfortunate because I think that OSPF is probably the best dynamic routing protocol ever created. Still, I can also partially understand Microsoft's decision to remove it, as I would venture to guess that 99.9% of Windows Server administrators never used it. So what are we left with?
With the removal of OSPF, we are left with either 1) static routing or 2) dynamic routing with RIPv2. Let's find out how each of these works.

Should you use static or dynamic routing?

The question of whether you should use static or dynamic routing is really a question of administrative overhead. In the end, the result of your network traffic being routed to the correct network should be the same, no matter which method you choose.
With static routing, you must make an entry on your Windows Server for every network that will be routed by that server. Thus, for a simple network with a single Windows server, routing traffic between two networks, static routing is a "no brainer." You could configure it with two simple route add commands.
On the other hand, on a network where you want the Windows Server 2008 system to route for 25 networks or to exchange routes with a Cisco network that uses RIP, you will want to choose dynamic routing. Obviously, you do not want to have to key in those 25 networks manually, nor can you provide the true dynamic features that RIP provides.
Speaking of that, what does dynamic routing provide? Let's list out some features:

• Ability to add networks automatically by learning them from other RIP routers.
• Ability to automatically remove routes from the routing table when other RIP neighbors delete them.
• Ability to select the best route based on routing metrics.
• Ability to reduce configuration of Windows Server routing systems that have more than a few static routes that need to be added.

So how do you configure static and dynamic routing in Windows Server 2008?

Static routing in Windows Server 2008

Static routing in Windows Server is nothing new. We have been using the route command for years. You can configure static routing in Windows 2008 Server using either the route command or using the GUI. However, if you use the Windows GUI interface, those routes will not be listed in the command line interface (CLI) when you type route print. Thus, I strongly recommend that if you are going to use static routing in Windows 2008, you just use the route command at the Windows command prompt.
So let's look at some examples of how you configure static routing using the route command:
Show the static routing table
Showing the static routing table is easy. Just use the route print command, as you see in Figure 1 (below):

Figure 1: Showing the IP Routing table in Windows Server 2008

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In the route print output, the first important thing that you see is the interface list. Windows Server IP interfaces are labeled with an interface number. The interface numbers in Figure 1 are 16, 14, 1, 15, 20 and 12. These interface numbers are used whenever you add or delete routes to the routing table.
The second important thing is in the route print output IPv4 Route Table. This shows us the network destination, network mask, the default gateway, interface, and metric. This table tells the Windows Server where to route the traffic.
Below that is the IPv6 routing table. For more information on IPv6, I recommend Brien Posey's articles Representing an IPv6 address and IPv6 network notation and subnetting, and Mitch Tulloch's article IPv6 Support in Microsoft Windows.
Add a static route
So how do you add a static route at the command line? The answer is easy: Use the route add command like this:

route add 1.1.1.0 mask 255.255.255.0 10.0.1.1 if 1

As you see in Figure 2, the result of our route add was an affirmative "OK!"

Figure 2: Using the route add command in Windows 2008

What was important in the route add command was the network we want to add, its subnet, the destination/gateway, and the interface for that route.
Delete a static route
Deleting a route is even easier than adding one. All you have to do is tell route delete the network that you want to remove, as you see in Figure 3.

Figure 3: Using the route delete command in Windows 2008

So those are the basics of configuring static routes at the command line. Now let's learn about configuring dynamic routing.

Dynamic routing in Windows Server 2008 using RIPv2

Earlier in the article, I talked about the benefits of configuring dynamic routing. So now let me show you the steps to configuring RIPv2 in Windows 2008:

1. The first step is to install the Routing and Remote Access (RRAS) role in Windows 2008 Server. If you go into the Add Roles Wizard, the RRAS role can be difficult to find because what you really need to add is the Network Policy and Access Services role, then the Routing and Remote Access Services Role (as you see in Figure 4 and Figure 5):

Figure 4: Adding the RRAS Role through the Network Policy and Access Services

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Figure 5: The Win 2008 Role Services are part of the Network Policy and Access Services Role

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Once RRAS is installed, you can configure it from the Server Manager application, but I prefer the Routing and Remove Access application.

2. The second part of this is to Configure Routing and Remote Access by opening the RRAS MMC, right-clicking on the server name, and clicking Configure and Enable Routing and Remote Access, like this:

Figure 6: Configuring and Enabling RRAS

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Make sure that you do a Custom Configuration concerning what RRAS protocol to install. Then, choose to install LAN ROUTING , then choose to start the service.
From there, you can see the Network Interfaces controlled by RRAS and specific configurations for IPv4 and IPv6.
At this point, you can expand IPv4, go to General, then to New Routing Protocol (as seen in Figure 7):

Figure 7: Adding a new Routing Protocol

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Next, choose to install RIPv2 as your routing protocol:

Figure 8: Adding RIPv2

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3. Now that you have RIPv2 installed, you can configure it. Configuring it is really as easy as adding the interfaces that you want to use to exchange RIP routes with. To do this, go to the RIP section, right click, click on New Interface and select the interface you want to add under RIP, as you see in Figure 9:

Figure 9: Adding a new RIP interface

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4. After selecting the interface, you have the option to configure a wide variety of RIP connection properties, as you see in Figure 10. There is more to configuring RIP than I can go into in this article because RIP configuration can be very simple or can become very complex:

Figure 10: Configuring the new RIP interface

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5. Once you have your RIP interfaces added, you can check to see whether you are sending and receiving responses on your RIP interfaces (you should be). You can also check to see whether you have any RIP neighbors by right-clicking on the RIP protocol, then clicking Show Neighbors.

Before I conclude this section about RIP in Windows, I want to point you to a couple of excellent resources I used while preparing for this article:

1. Recently I was watching Ed Liberman's Train Signal Windows 2008 Network Infrastructure video. In that video, besides explaining routing and the differences between static and dynamic routing, Ed shows, step by step, how to configure RIPv2 in Windows 2008. I found the video very helpful and recommend it to you whether you just want to learn about Win 2008 and routing or whether you are looking to pass Microsoft's Windows 2008 Network Infrastructure exam (70-642). Here is a screenshot of Ed configuring RIPv2:

Figure 11: Train Signal's Windows 2008 Video on how to install and configure RIPv2

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2. Over at the Petri IT Knowledgebase, I wrote an article on how to configure exchange RIP routes with a Cisco router in Windows 2003, then another article on proving Cisco router exchange route configuration with a Windows server. While not pertaining to Win 2008, the process of configuring RIP on Win 2003 is similar, and the configuration to exchange routes with a Cisco router is very relevant. Summary
   Windows Server 2008 has one solid static routing option and one scalable dynamic routing option: RIPv2. I discussed how OSPF has been removed from Windows 2008 (and how I feel about that). We talked about whether to use static routing or dynamic routing. Finally, I showed you how to configure static routing with the route command and dynamic routing by installing RIPv2 in Windows 2008 Routing and Remote Access.