Nortel BayStack 5510-24T Specifications page 6

QoS and policy management
DiffServ QoS enables networks to read, alter, prioritize, tag, or mark IP packets based upon
information embedded in the Type of Service (ToS) field. The level of service can be marked
in the embedded information inside the ToS field of each IP packet. DiffServ is based on the
ToS field. BayStack 5510 Switches have application-specific integrated circuits (ASICs) to
enable the DiffServ Code Point (DSCP) to be mapped to the IEEE 802.1p user priority bits
to provide consistent QoS at Layer 3 (IP) and Layer 2 (Ethernet). The QoS policies can be
configured via the BayStack 5510 Switch's built-in Web-based management tools to facilitate
QoS. Alternatively, Optivity Policy Services can be utilized for dynamic end-to-end enter-
prise-wide policy and QoS management.
Simplified QoS
BayStack 5510 Switches support Nortel Networks Service Classes (NNSC) which provide
simplified QoS provisioning. NNSC provides factory-default QoS configurations, eliminating
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 5510 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 5510 Switches also have the ability to read packets that have been marked from
other devices such as the Passport 8600 Switch. Additionally, weighted round robin prevents
normal priority traffic from being starved by expedited traffic (on a per-packet basis).
BayStack 5510 also supports strict priority queuing.
Quality of Service provisioning
With Optivity Policy Services software, policies can be created through a simple and intu-
itive 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
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