THE CABLED PART OF WIRELESS

Although it may seem like an oxymoron, the "wired" side of wireless networks must be carefully planned and installed in order to take advantage of the faster 802.11n technology. 802.11n offers many advantages for the wireless portion of enterprise networks. Before those advantages can be realized, the wired infrastructure needs comprehensive evaluation. 802.11n Access Points

The wired link between an Ethernet switch and the wireless access point can affect overall WLAN performance.

might require new cabling, but some or all of the existing cable could suffice. There is only one way to know for sure: test it.

WHY 802.11N?

INCREASED SPEEDS. At 200 Mbps, 802.11n is about four times the speed of 802.11g wireless. If higher data rates are achieved, so much the better.

BETTER COVERAGE. 802.11n Access Points offer greater range and promise to reduce the number and size of "deadzones." This translates to fewer access points and simpler management.

FLEXIBILITY AND COST. If users roam or change work areas frequently, then it is easiest to support them with a wireless LAN. Equally compelling is cost. The price of copper has doubled since early 2005 and tripled since early 2004. This is reflected in the cost of twisted-pair cable.

OPTIONS FOR 802.11N ACCESS POINT CABLING

INSTALL NEW CAT 6 (OR BETTER) CABLE. Proper installation followed by certification to TIA Cat 6 link performance standards will remove any doubt in support for 802.11n Access Points. For some organizations, however, the cost of new wiring is prohibitive.

TEST EXISTING CABLING. Proper testing may determine that a good deal of installed twisted-pair cabling links may be already suitable for 802.11n Access Points. A program to re-test installed twisted-pair can save a network owner significant money and raise the confidence in the deployment of 802.11n.

RECOMMENDED TEST STEPS

 All 802.11n uplinks should be able to support 1 Gigabit Ethernet (1000BASE-T) traffic.

CAT 5. The Category 5 cabling standard predates the IEEE 1000BASE-T standard, so Cat 5 was not defined to support 1 Gigabit Ethernet. But before retiring it and investing in new cabling, a certification test for compliance to the Cat 5e standard will indicate if 1 Gigabit support is possible. Many high-quality Cat 5 links will pass the certification test to the TIA/EIA-568-B Cat 5e performance level. If they do, you have assurance it is a usable uplink for an 802.11n Access Point. CAT 5E. The Category 5e cabling system was designed for 1 Gigabit Ethernet. Certifying an installed link to TIA/EIA-568-B Cat 5e performance is definitive proof that it is ready for 802.11n Access Points. CAT 6. Category 6 cable is more than sufficient to support 1 Gbps traffic if it was certified upon installation and no changes have been made. If there is any uncertainty about its status, it's a good idea to recertify to TIA/EIA-568-B.

Upgrading to 802.11n may encompass upgrading Ethernet switch ports or replacing the entire switch. If the twisted- pair cable and patch cords are already in place, the certification should be done as a channel test. That is to say, include the installed patch cords in the test configuration and use channel adaptors with the cable certification tool and select the channel test. If the patch cords are not in place, the test should be a permanent link test.