Network engineers who refresh the edge of their campus local area network (LAN) will face a fundamental choice: Stick with 100 Mbps Fast Ethernet or upgrade to Gigabit Ethernet (GbE). Vendors will undoubtedly push network engineers toward pricier GbE, but network engineers need to decide for themselves which infrastructure is right for the business.
Enterprises refresh servers, desktops and laptops continuously, but the edge of the campus LAN usually has an extended lifecycle. Your next LAN edge refresh might remain in place for five to seven years, so you should weigh the choice between Fast Ethernet and GbE carefully.
“While everyone is off building the new data center or constructing the new virtual infrastructure, the network infrastructure out at the edge continues to age and in some cases lag behind,” said Michael McNamara, technical consultant for Philadelphia-based Main Line Health.
Main Line Health began its transition from Fast Ethernet to GbE in the LAN edge in 2007, McNamara said. The company installs Gigabit switches in the campus LAN of any new construction or renovation projects. McNamara estimated that 35% of the edge port on his 35,000-port network is GbE.
Price is not the only inhibitor to a Gigabit Ethernet upgrade
Despite the relative maturity of GbE, it still holds a significant price premium over 100 Mbps. GbE ports can cost four times the price per port of Fast Ethernet, according to IDC. The price gap between Fast Ethernet and GbE switches may be the most obvious factor for most network engineers considering the network upgrade. However, the issue is far more complex.
The migration from 100 Mbps to GbE involves more than the replacement of switches in the wiring closet. Many mid-range models of VoIP phones offer a 10/100 Ethernet pass-through that allows a phone and desktop PC to share a network connection. Migrating that desktop to GbE would require a gigabit VoIP phone or a second network drop to the user’s desk, both which would add to the expense to the project. A GbE upgrade will also require a rip and replace of any pre-standard Power over Ethernet (PoE) and legacy CAT3 cabling.
“We are working through a recent acquisition, and we're finding that a lot of shortcuts were taken with the physical cabling plant that now needs to be addressed,” McNamara said. “I've also seen a lot of people just ignore and minimize their cabling plants and they usually end up paying for it in the long run.”
Finally, network engineers must ask themselves one fundamental question before upgrading to Gigabit Ethernet: Do you need that much bandwidth? In many cases, end-user applications are simply not consuming all the bandwidth of Fast Ethernet, making the additional capacity of GbE appear to be a pointless investment. Network engineers, armed with network performance baselines, can likely argue that 100 Mbps provides enough capacity for their network edge.
Network administrators, however, need to weigh their current bandwidth needs on the local area network against projected network demands over the next five years. VoIP and telephony has already migrated onto Ethernet in most enterprises, leading to increased bandwidth requirements. Video is the next form of media to drive up bandwidth demand, with desktop video conferencing and IP video security cameras being deployed in many enterprises. Broader use of wireless devices, including laptops, smartphones and tablets, will increase traffic on wireless LAN infrastructure, which in turn will impact the wired backhaul network. Network capacity planning should account for all of these disparate systems converging on Ethernet, along with the general growth of the organization.
Making the case for a Gigabit Ethernet upgrade
Improved performance is the most obvious argument for migrating from Fast Ethernet to Gigabit Ethernet, but the upgrade can also impact manageability, quality of service (QoS) and security.
GbE switches have the latest generation of network management features, allowing network administrators to assign QoS and security policies to specific applications.. As private cloud services and IT service management become more common throughout enterprises, these advanced management features will help network administrators guarantee service level agreements and enhance security. While vendors offer Fast Ethernet switches with similar management and security functionality, they charge a premium for them that narrows the price gap with GbE.
As 802.11n-based wireless LAN technology matures, the throughput capabilities of many wireless networks will exceed the bandwidth of a backhaul network based on Fast Ethernet.
“Bringing 802.11n access points in the enterprise will absolutely require Gigabit Ethernet,” said Rohit Mehra, director of enterprise communications infrastructure for IDC. The 802.11n standard has a theoretical throughput of 300Mbps and higher. A LAN with 100 Mbps edge will be a bottleneck for an 802.11n wireless LAN overlay.
Additionally, many wireless access points and other IP devices like video cameras and conference room switches now have power requirements that exceed the 12.94 watts produced by the original Power over Ethernet (PoE) standard. The new enhanced PoE+ standard, 802.3at, delivers 30 watts of power. PoE+ is available on the latest GbE switches from major networking vendors, but vendors are not updating their existing Fast Ethernet switches with the new power standard. If an enterprise deploys devices that require PoE+ for power, upgrading the edge to Gigabit might be more efficient than installing individual power injectors on a legacy Fast Ethernet network.
Finally, while delivering more bandwidth and more robust management, GbE switches are also more energy efficient than the previous generation of switches, Mehra said. This offers enterprises the opportunity to lower their power consumption on the network edge.
This was first published in February 2011