Tuesday, October 06, 2009

Why The WAN Lags The LAN

Networks are often thought of as nearly transparent to the flow of data between nodes. Corporate LANs are managed to ensure there is enough bandwidth to prevent productivity killing network congestion within the organization. But it doesn’t take long to find the real choke point in most networks. It’s the connection with the outside world, called the WAN.

The WAN or Wide Area Network differs from the LAN or Local Area Network in more than name. They traditionally use completely different technologies.

LANs are based on the Ethernet standard. Devices that connect to the LAN have standardized NICs or Network Interface Cards. That includes PCs, servers, printers and other peripherals. The most popular interface is 10/100 Mbps. That means the device will operate on Ethernet LANs running at the standard 10 or 100 Mbps speeds. The 10/100/1000 Mbps interface is becoming more popular and increasingly seen in new devices. It maintains compatibility with 10 Mbps Ethernet and 100 Mbps, also called Fast Ethernet, and adds a new speed of 1000 Mbps, also called Gigabit Ethernet or GigE.

Now, compare these network speeds with typical WAN connections. The most popular WAN service is the T1 line running at 1.5 Mbps. Larger businesses often have DS3 connections that run at 45 Mbps. Only the largest or most bandwidth-dependent organizations have higher speed fiber optic WAN connections. These range from OC3 at 155 Mbps to OC48 at 2.5 Gbps. The largest ISPs and telecom carriers may have backbones at OC-192 or 10 Gbps. Nationwide fiber optic network backbones run at OC-768 or 40 Gbps.

Chances are your business is likely running a LAN network at 100 Mbps. When you access the Internet or connect to another of your company’s facilities via dedicated point to point data line, you may be connecting over a T1 line at 1.5 Mbps. That’s almost two orders of magnitude difference. You’ll notice the difference in file transfer times. Within the walls of your building file transfers might be measured in seconds. Go outside and the same size files will require minutes.

A larger corporation might have a LAN backbone running 1000 Mbps between switches and perhaps even to the desktop. If your WAN connection is DS3 at 45 Mbps, you still have a substantial choke point for data entering and leaving the organization. It can be a significant bottleneck when running overnight file backups to a remote data center or transferring important files to a client. If your desktop computer is connected at 100 Mbps, the slowdown might be a little more than double. But if you are transferring between two servers that have 1000 Mbps connections, the slowdown to 45 Mbps is more like 20x.

So, why don’t companies just increase their WAN bandwidth to match their LAN bandwidth? The reason is cost. WAN connections have traditionally been very expensive. Management can rationalize that the company generates far more traffic across its LAN than goes out on the WAN, so that a slower WAN isn’t that much of an impediment. Well, that depends on what is entering and leaving the building. If customers can’t access your servers in a reasonable time, they’ll think your website is broken and go elsewhere. If your medical organization can’t transfer medical images in a reasonable time, staff might be tempted to shy away from electronic medical records.

Is there anything that can help this situation? Probably the most promising technology is Carrier Ethernet, also known as Metro Ethernet. Prices for Ethernet WAN connections are significantly lower in general than traditional telecom service pricing. Bandwidths that match LAN speeds of 10 Mbps, 100 Mbps, 1000 Mbps and 10 Gbps are readily available at quite reasonable pricing.

With a better WAN to LAN bandwidth parity, network performance will be much more consistent, regardless of file source and destination. That can really help productivity and encourage staff to make better use of electronic file transfers and paperless office techniques.

What will it cost to improve your network’s WAN connection performance? Probably less than you might think. Even if you don’t match your LAN speed completely, you can likely get more bandwidth for your current budget. To find out how much, check Ethernet WAN bandwidth service pricing now.

Click to check pricing and features or get support from a Telarus product specialist.

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