In-Depth

Wrangle Your Growing Network with Routers

Your network needs are expanding. How do you meet these needs without getting bogged down? It’s time to consider routers to keep things running smoothly.

• By Chris Brooke
• 11/01/1998

I’m feeling misty today. My baby is growing up. It seems like only yesterday that I brought home my first hub: a cute little eight-port model with beautiful green lights. I got such a kick out of watching it grow as we added more segments. But, this old house just isn’t big enough anymore, and we have to move on. Yes, today my little baby LAN is becoming a WAN. Like the tiny acorn that becomes the mighty oak, our “home” has grown beyond these four walls.

Does this sound familiar? Are you similarly wistful as you prepare to expand your business to a new location? For most small businesses, the need for routing solutions coincides with the addition of a branch office. The size and function of that office determine the degree to which the two locations need to be interconnected. We’ve taken a look a some entry-level routing solutions that may help you on the road to WAN-dom. We’ll talk about capabilities vs. price, plus try to help you avoid some common pitfalls. First, let’s start with a basic overview of routing.

I’ve Got One Hand in my Packet…

Those of you who’ve passed the Networking Essentials exam or have been MCPs for a while are no doubt aware of the limitations of local area networks. You probably have the “max. distance between concentrators” memorized for each media type, to say nothing of the worlds of fun you’ve experienced with hubs, repeaters, switches, bridges, and partridges in pear trees. Unfortunately, by definition LAN means local area network. Routers make wide area networks possible.

Essentially, a router is a device that forwards packets or frames from one network segment to another based on information stored within its routing table. It can connect two or more segments of various types and topologies. It can usually be configured to learn as it goes, building and modifying its routing table as it determines the shortest path to various destinations. It also reduces network traffic because it doesn’t forward a packet to a segment that doesn’t need it. There are many types of routers, depending upon what they’re used for. Some common router applications include:

• Remote Access Server—A RAS server qualifies as a router, albeit a very limited one. It usually consists of an NT Server connected to a LAN that provides dial-in access, dial-out access, or both.

• ISDN Router—Similar to RAS in function, an ISDN router takes many large steps forward. First on the list is increased bandwidth. Additionally, many ISDN routers have built-in hubs for connecting directly to your network. Some can also be configured to provide DHCP configuration to hosts on the network and also perform network address translation (NAT), much like a proxy server.

• Windows NT Server—Given the low cost of computer parts these days, this setup is probably the most cost-effective, limited-use routing solution. It consists of a computer with at least two network interface cards (NICs) running NT Server. Once “IP Forwarding” is enabled in the TCP/IP Network Properties and Routing Information Protocol (RIP) is installed, the server becomes a “smart” router, able to build its own routing table. As the network grows and the load increases, however, most administrators opt for hardware solutions.

• Dedicated Router—Everyone’s heard of Cisco routers. Cisco Systems, Inc. is probably the largest router manufacturer in the world. There are others, however: 3COM, Intel, and Osicom, to name a few. Depending upon their capabilities, dedicated routers can range in price from a few hundred to several thousand dollars. These are most often used when connecting several WAN segments via leased lines.

How Much is that Router in the Window?

Depending upon the routing solution you choose, costs can vary greatly. Router cost is only part of the overall cost of connecting two or more offices, however. ISDN is far cheaper than, say, a leased T1 line, but even ISDN rates vary from telco to telco. For that matter, so do T1 rates. On average, however, a Basic Rate ISDN (BRI) line is about $100 per month, not including installation and equipment. Additionally, some phone companies charge per minute of line usage. For this price you get two ISDN “B” channels capable of either 56 or 64Kbps. These two channels can also “multi-link” for a combined bandwidth of up to 128Kbps—quite a jump from a 33.6 modem!

A full T1 averages about $1,200 per month, again, not including installation and equipment (which can be significantly more pricey than ISDN equipment). A T1 can be leased in fractions, however, which lowers costs along with bandwidth. T1s are dedicated, “always-on” connections, which means that the cost is the same regardless of whether you send 1M or 100G of data in a month.

Now that you have an understanding of the basic technologies involved, let’s look at some real-world scenarios based on need, starting at the low end and working our way up.

Disclaimer: Any similarity to the Microsoft exam format is caused by a lack of originality and a deep and abiding interest in scaring the bejesus out of the readers. Plus, I’ve taken so many tests, I now think in scenario format!

Situation: You’re the head of the IT division of a growing company. You’re preparing to expand to a branch office and need to provide connectivity between the two networks. You need to allow users in the branch office to exchange e-mail with the home office and the Internet. E-mail service is provided by an Exchange Server located in the home office. How can this be accomplished?

Answer: Easy. Get yourself a 56k modem and set up a RAS server in the home office. It’s cheap, easy to install, and adequate for your bandwidth needs. The branch office can connect either with modems connected to the individual workstations (expensive if you have more than a few users) or by setting up a RAS server for dial-out connection to the home office’s RAS server (a better solution).

Situation: Same as the previous situation, except that your bandwidth needs have now increased. People need to share files between the branch and home office, and there’s a nightly update to the server of approximately 10M.

Answer: It’s time for ISDN. Set up an ISDN router at each office. If the branch office is small, you can use one of the routers I mentioned earlier with a built-in hub and DHCP capability.

Situation: Same as the previous situation, except that there will be constant (but light) traffic between the two offices. Users in the branch office need to log into a server in the home office. Home directories are located in the home office, as well.

Answer: Lease a fractional T1 and set up a router at each office. These can be in the low price range of dedicated routers. In fact, this situation is ideal for two NT Servers acting as routers. Just remember that when you lease the T1, you’ll also have to lease a Channel Service Unit/Data Service Unit (CSU/DSU) for each end. This device converts the computer network signal to the digital format used by the telephone network. Many dedicated hardware routers have this functionality built in. (See the chart on page 27 for routers that have this feature.)

Situation: Yadda, yadda, yadda, except that both offices require high-volume/high-speed access to each other as well as to the Internet.

Answer: Lease a T1 connection to the Internet for each office from a local ISP. Establish a router-to-router virtual private network (VPN) using Layer 2 forwarding (L2F) or a similar technology. This is plush! Private traffic is tunneled through the Internet and public traffic goes directly to the Internet. Each office maintains the needed high-speed Internet connection but without the added expense of a private T1 between them. Cool, huh? Most of the low- to moderately priced routers are capable of this. (Again, see chart on page 27).[For more information about VPN see “Your Own Private Internet” in the October issue.—Ed.]

Situation: Bill Gates just invested heavily in your company and you need to open 17 branch offices. Each office requires a high-speed connection to the home office and all other branch offices. Internet access for all offices is required, but traffic to the Internet from all offices is light to moderate.

Answer: Multiple private T1s with a high-end, supercharged, heavy-duty (you get the point) router connecting all the segments together. A T1 line to the Internet from the home office can provide Internet access for all offices.

Where Do You Fit In?

Chances are that your situation falls into one of the first three scenarios (but wouldn’t it be cool if it were the last one?). Before you decide which solution to use, remember this advice:

• Plan for growth—A RAS server or ISDN connection may be sufficient today, but how well will it suit you tomorrow (metaphorically speaking)? If you don’t adequately plan for growth, you’ll wind up spending a lot more time than necessary replacing one technology with another before the first has even collected any dust. Spending a little more initially can save money down the line.

• Plan for failure—Always have a backup plan. If you’re going to deploy a T1 connection between your home and branch office, have ISDN or RAS as a backup in case of network failure or a twitchy CSU/DSU. Again, it’s more out-of-pocket initially, but you’ll end up paying more in lost productivity as your employees play Solitaire while waiting for the network to come back up.

• Be realistic—Don’t buy more technology than you’ll ever use. If a fractional T1 is more than adequate for future growth, why spend extra on more? You can increase the lease later if Mr. Bill does, indeed, invest in your company, but don’t count on it! Plan for growth, not miracles.

• Don’t forget security—This is true especially when dealing with VPNs. If you ask 10 network security experts about the security of VPNs, you’re likely to get 10 different answers. Ultimately, though, there are only four levels of network security:

• Totally Secure—You unplug the network cable.
• As Secure as Possible—You implement all the super-expensive, state-of-the-art security protocols (unnecessary unless you’re the defense department).
• Secure Enough—You take adequate security precautions based on the sensitivity of the information traversing your network.
• Totally Unsecure—Don’t do this.

Just So No One Feels Left Out…

The routing solutions I’ve discussed represent only a portion of the connectivity options available. The online chart is an overview of affordable routers within a variety of capabilities; by no means should it be considered all-encompassing. There are other network technologies available as well, particularly if a VPN is well-suited to your needs. Once you’ve found a VPN technology that you like, all you need is Internet access. Many companies offer cable modem Internet access to businesses. This provides T1 speeds at about one-tenth the cost. xDSL is another high-speed alternative, sorta-kinda similar to ISDN in that it uses existing phone lines. xDSL is coming soon to a theater near you.

One more thing: Just because you don’t have a branch office doesn’t mean a router isn’t useful. If you have a large local network, a router is an excellent tool for dividing the network into segments, thus reducing traffic on each segment. This is definitely something to consider, particularly if you’ve been experiencing problems with contention.

Just remember to take lots of pictures of your LAN while it’s still young. (Sigh!) They grow up so fast.