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QoS/Policy Manager
OmniSwitch Troubleshooting Guide September 2005 page -15
QoS/Policy Manager
Policies describe subsets of traffic, and what to do with that traffic. The Policy Processor determines what
policies are enforceable, and organizes the policies into lists used by the classifier. QoS uses the same
policies for Prioritization/Shaping, IP Filtering (ACLs), NAT, and IPMS Filtering. Using the same poli-
cies for all these functions has several benefits:
• All policies affecting the traffic are centrally located
• All policies share the same expressive power.
• Traffic is only classified once in a single routine.
• A single GUI application (PolicyView) can manage policies, and subsequently manage all these facili-
ties.
QoS determines which policies can possibly be matched on a switch, and constructs lists for each of the
L2 and L3/L4 classifiers. If a policy contains classification criteria that cannot be met by the hardware,
QoS logs a message indicating what parameters could not be matched, and the policy is not used in classi-
fication.
The QoS manager calls the classifiers in response to messages from source learning, routing, and IPMS.
QoS uses lists maintained by the QoS Policy Processor to make it’s decisions.
Coronado Egress Logic
• Coronado receives a packet from the Fabric through FBUS destined for a Queue existing on the same
Coronado. There is not a lot of egress Logic to be performed for Unicast packets.
• If the destination port is untagged, 802.1Q tag is stripped and the packet is forwarded to the destina-
tion port.
• Coronado limits the flood bandwidth or Flood and Multicast Bandwidth per port. Bandwidth limita-
tion is based on dual leaky bucket algorithm. Packets are credited in chunks of 64 bytes every
130.98us.
• IPMS processing is completed by the Coronado on the egress, started by the HRE.
• Updates IPMS routed packets- decrements TTL and rewrite MAC-DA.
• Duplicates the packet whenever needed. Multicast packets are duplicated by the software on a Q-Tag
link.