Simplified QoS should ease convergence

In April, we covered some automated quality-of-service provisioning capabilities now available for enterprise switch and router gear. We received several notes from readers expressing interest in this subject, so we thought we’d delve into a bit more detail.

We’re aware of at least three enterprise network equipment makers that automate the process of marking, classifying and queuing packets: Alcatel, Cisco and Nortel. Depending on vendor, there are a few ways to use the automated QoS features, which are becoming a must for converged enterprise networks supporting low-latency applications such as voice over IP (VoIP):

* You can configure a single device using a very abbreviated set of commands, which turn on the appropriate QoS settings in the background.

* You can do what’s described above, then copy the configuration to a network management system for subsequent enterprisewide propagation.

* You can start at the network management level to set policies and invoke corresponding, preset QoS templates across the network.

The relevant management modules involved here are Alcatel’s OmniVista 2000 PolicyView, Cisco’s CiscoWorks QoS Policy Manager (QPM) and Nortel’s Optivity Policy Server.

This time, we’ll examine the Alcatel system, then describe the other vendors’ approaches in our next newsletter.

Alcatel tackles the automated QoS provisioning task from the network management side. The OneTouch QoS feature in Alcatel PolicyView enables point-and-click implementation of complex priority schemes that, behind the scenes, invoke settings for 802.1Q, 802.1p, Resource Reservation Protocol, Differentiated Services Code Point (DSCP), IP type of service (ToS) and other QoS mechanisms.

The settings are invoked based on the policy associated with the application, time of day, source and destination MAC addresses and other parameters, and are then pushed out to the infrastructure devices, says Alcatel senior product manager John Reidy. He adds that the network management capability is decoupled from the operating system version of the devices.  

For prioritizing VoIP, the network administrator configures the IP address of one or more subnets of VoIP phones and clicks the “apply” button, Reidy explains. All devices on that subnet get a DSCP marking of “8” as the highest priority, he says. To prioritize data, the administrator selects one or more servers that require high-priority access, then defines the level of services for each, which Alcatel defines as platinum, gold, silver or bronze but actually mask DSCP settings 7, 5, 3 and 1.

Finally, an “expert mode” lets you revert to the granular complex control of tuning any and all QoS knobs as you see fit, based on ingress/egress IP addresses, TCP/UDP ports and VLAN groups using DSCP, ToS and 802.1p markings, according to Reidy.