Nortel BayStack 5520-24T-PWR Specifications page 9

Simplified QoS
BayStack 5520 Switches support Nortel Networks Service Classes (NNSC) which provide
simplified QoS provisioning. NNSC provides factory-default QoS configurations, eliminat-
ing the complexities often associated with QoS-enabled network deployments.
NNSC provides default settings such as:
• DSCP marking per class
• DiffServ forwarding behavior (PHB) per class
• DSCP to queue mapping
• DSCP to 802.1p mapping
• Default scheduler per class
By classifying the traffic and placing it into an NNSC, complex QoS configurations are elim-
inated. NNSC simplifies the deployment of a QoS-enabled network with Nortel Networks
switching solutions, using a Web-based interface. This not only saves on provisioning time
but most importantly, ensures that the QoS functions are provisioned consistently across
the network.
Queuing function
BayStack 5520 Switches provide network availability for mission-critical applications,
devices, and users by classifying, prioritizing, and marking LAN IP traffic using up to eight
hardware-based queues on every port including the stacking ports. This is based on the
following parameters:
• MAC address-based filtering
• IP ToS/DSCP marking
• IP source address/destination address or subnets
• TCP/UDP source/destination port/port range
• IEEE 802.1p user priority bits
• Ingress source port
• IP Protocol ID (e.g., TCP, UDP, IGMP)
• EtherType (e.g., IP, IPX)
• IEEE 802.1Q VLAN ID
BayStack 5520 Switches also have the ability to read packets that have been marked from
other devices such as the Passport 8600. Additionally, weighted round robin prevents normal
priority traffic from being starved by expedited traffic (on a per-packet basis). BayStack
5520 also supports strict priority queuing.
Quality of Service provisioning
With Optivity Policy Services software, policies can be created through a simple and intuitive
drag-and-drop workflow. Optivity Policy Services is the Policy Decision Point in a DiffServ
QoS implementation.
Further benefits include:
• Simple intuitive policy creation
• Ability to re-use common filter sets
• Provision of a network-wide view of policies currently in use
• Ability to avoid QoS provisioning errors
• Centrally managed DSCP and 802.1p queue mapping tables
• Saved time in provisioning the network—as thousands of CLI or Web transactions
are reduced to a few simple actions
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