Networking

Aging Network Creates an Opportunity for Upgrade

I have a business computer network for 275 users that's been mostly reliable, but is getting old and causing problems. I think it's time to refresh the hardware, but I'm not sure whether I need gigabit or if I can stay with 100 megabit for my users. What do I need, and where should I look?

This is a very good question, and timely. Network switches tend to have a long lifespan, and generally “just work,” causing them to be largely ignored unless they fail or begin under-performing. Many networks the size of yours were built or upgraded some time in the past decade, and those networks are now showing their age, meaning they’re ripe for replacement. Basically, now is the time to build your network for the next 10 years.

First off, there’s no reason to go with 100 megabit switching for your users. The low cost and prevalence of gigabit switching coupled with the fact that nearly all desktop PCs are now equipped with gigabit network interfaces makes the move to gigabit a no-brainer. For many day-to-day tasks your users may not notice the difference between 100 megabit and gigabit, but the extra bandwidth afforded by gigabit to the desktop cannot be overstated when working with more modern applications and the larger files they produce. In addition, as we transition into a more connected business environment, these users will be placing heavier loads on the network with increased voice and video traffic.

This also means that your servers may need heftier connections as well. You’re probably already using gigabit interfaces for your servers, but as you add faster devices to the network, those interfaces may begin to see some congestion. To address this issue, you may want to look into 10GB interfaces for your busier servers, and perhaps add port aggregation to other servers. Port aggregation protocols like Cisco’s EtherChannel can bond multiple gigabit links into a bundle, providing much more bandwidth for that server without incurring the cost of 10GB network interfaces and switch ports.

For certain server-side applications such as databases, and certainly for shared storage, the extremely low-latency of 10GB can provide significantly faster response times and reduce the chance of network congestion during busy periods.

The choice of hardware can seem daunting at first, but can be simplified once you’ve determined your needs and budget. A good starting point is to determine the location of your wiring closets and datacenter, and inspect the current interconnection methods.

In a centralized layout, all the switching hardware is located within the datacenter, as all data drops are less than 300 linear feet from that room. This design will likely lead you to implement blade switches that can support hundreds of switch ports within a single chassis, including the ability to update individual switching blades in the future.

A good choice for this type of network layout might be the Cisco 4500 series modular switches. These switches are available in 3-, 6-, 7-, and 10-slot varieties, and can easily combine a multitude of switching types within a single unit. You may have one or more blades with Power-over-Ethernet (PoE) capabilities next to several gigabit or 10GB blades to support the servers. As your requirements grow, you can swap out older line cards with newer models without issue, and the 4500R models can support redundant supervisors to greatly increase reliability in critical areas.

In a layout with multiple wiring closets scattered around the location, you’ll need to determine how many ports are present in each closet, and how many are currently utilized. For small closets you may be able to install 24- or 48-port switches with multiple gigabit or 10GB uplinks back to the main server room. Larger closets may benefit from stacked switches to increase port availability.

Good candidates for this type of closet might be the Cisco 2960 series. These switches can provide 24 or 48 gigabit copper ports with or without PoE, and have a selection of uplink types from 10GB to multiple copper or fiber gigabit ports to support a variety of installations. In addition, the Cisco 2960-S models in this series can be stacked with Cisco’s FlexStack technology that allow multiple physical switches to be combined into a single logical entity to make management simpler, and to provide increased redundancy, as the uplink ports on each switch can be utilized for the whole stack.

As a rule, the more time taken to plan out a network refresh will result in a more robust and scalable solution than simply buying newer versions of the same hardware.

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