Taking A Look At The Copper Alternative

Network executives now have the option of using ordinary unshielded twisted-pair copper cabling for gigabit Ethernet switch connections for short distances at half the cost of fibre.

The IEEE 802.3ab Task Force ratified the 1000Base-T copper interface standard in June, 1999, and some vendors have begun offering the necessary copper-based physical interfaces on their gigabit Ethernet switches. The good news is that Category 5 cable is installed in most buildings in North America, which means there’s no cable installation cost, except for the new connection itself.

There are two catches, however. First, the existing Cat 5 cabling you have in your LAN may be adequate for carrying Ethernet and fast Ethernet, but it may not be up to snuff when it comes to gigabit Ethernet. The cable connections in the wiring closet may not meet the new standard, the cables may be improperly installed, or there may be other kinds of wiring problems that never came up when you were running electrical signals far below a gigabit.

If your cabling is up to spec, the other catch is that you can only use copper cable at gigabit speeds for runs of 100 metres or less.

There are, however, many types of installations that fall within that 100-metre limit, including horizontal runs between wiring closets on the same floor; vertical risers between floors, within wiring closets and data centres to interconnect multiple workgroup switches; and backbone switches, to connect servers and to connect high-performance workstations to switches. In that case, for example, Cat 5 cable would be connected to a 1000Base-T port on the switch and a 1000Base-T port on the workstation network interface card (NIC).

Fibre-optic cable is still required for horizontal or vertical building connections that exceed the 100-metre limit. Typically, this would be vertical backbone risers between a data centre on one floor and wiring closets on other floors.

Unfortunately, deployment has been slowed by the lack of availability of these copper gigabit Ethernet interfaces, which is due to semiconductor manufacturers not producing enough copper gigabit Ethernet interface chips to meet the growing demand.

But switch and NIC vendors are beginning to announce copper interfaces on their existing gigabit products as add-ons and also on new products.

Alteon WebSystems Inc., recently bought out by Nortel Networks, has introduced a 10/100/1000Base-T NIC, which autonegotiates to the highest speed and supports jumbo frames for improved server performance. Its copper ACEnic costs US$500, about half the cost of fibre NICs.

Extreme Networks Inc. has a copper-based Gigabit Ethernet switch, the Summit7i Internet Data Centre Switch. The Summit7i is available with 28 1000-Base-T ports for Cat 5 at about $700 per copper port. Extreme also has an announced an eight-port 1000Base-T module for its Black Diamond core backbone switch.

And Foundry Networks has a 1000Base-T interface module for existing Foundry switches. Foundry also introduced its FastIron II GC 1000Base-T workgroup switch, available with 16 or 24 1000Base-T ports, and its high-density FastIron II Plus GC switch with 64 1000Base-T ports. Foundry’s system-level price for a 1000Base-T switch is $650 per port, well below the price of its fibre ports.

State of the WAN

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