Rolling Review Wrap-Up: Vendors' RFP Responses Make The Case For Switching: Page 3 of 3

THE POWER OF VOICE
A full 66% of survey respondents indicate that support for real-time media, like VoIP and live streaming video, is a business driver for upgrades. Real-time media requires low latency and low-jitter networks in order to perform well. Unlike audio and video on demand, real-time media can't be buffered and smoothed out. On a per-call basis, the bandwidth required is small--a worst case is a VoIP call encoded using a G.711 codec (meaning no compression), which requires 80 Kbps. From a pure capacity perspective, a fast Ethernet connection can handle more than 1,000 VoIP calls simultaneously.

More important are latency, the delay between two endpoints, which should be less than 125 milliseconds, and jitter, the variation in per-packet delay, which should be less than 30 milliseconds.

The switching platforms presented by all the vendors use similar methods to support real-time media. Methods included automatically detecting a media endpoint on a switch port using LLDP and LLDP-MED, and placing the port into a voice virtual LAN configured for low-latency throughput, as well as marking and honoring quality-of-service settings on a per-packet basis.

LLDP and LLDP-MED also are used to manage other components of VoIP, such as setting the required Power over Ethernet (PoE) wattage on a per-port basis and providing location information to VoIP phones for emergency (E911) location. The key VoIP differentiator is support for vendor-specific attributes for phones. Alcatel-Lucent and 3Com have their own VoIP product lines; the others partner with VoIP vendors and integrate the VoIP equipment on their switch platforms.

The other issue to contend with is PoE. Wiring closet systems must be able to accommodate higher power and heat loads. We've heard horror stories about PoE switches overheating in poorly ventilated closets. Overprovisioning is a requirement to ensure that there's adequate power to phones.

All of the switches in the RFP responses can power a subset of their total ports using internal power supplies, but plan on making space for dedicated power modules to provide adequate redundancy. Be sure your switches support power prioritization, so that in the event of power loss critical systems stay online in an emergency. All of the vendors here support power prioritization.

(click image for larger view)

SECURITY IS A TOP DRIVER
Whether your organization has to comply with regulations or you're concerned about locking down IT systems, improving security is a common business driver, say 71% of survey respondents. Security features are fairly uniform across the switching lines here, with support for secure management over SSL, SSH, and SNMPv3.

But not all features are supported on all switches within a single line. For example, 3Com's 5500G access switch line supports DHCP tracking, which tracks DHCP requests and responses; ARP inspection, which maps MAC addresses to DHCP leases; and IP Source Guard, which maps IP addresses to ports. 3Com's 4200G switch line does not.

Of course, network infrastructure and network access control are tightly coupled. All the vendors in the Rolling Review either partner with a NAC vendor or resell a NAC vendor's equipment. The integration point is typically 802.1X and Radius. Support for Microsoft's Network Access Protection using 802.1X or DHCP also is common.

The combination of port security features and NAC makes user-based access control at the network edge possible with relatively minimal changes after initial configuration. HP ProCurve's Identity Manager applies access policies based on user name and group membership, location, and time of day, providing basic NAC features without the expense of a third-party product.