How To Optimize Performance When Using Acls - Avaya Cajun P882 User Manual

Chapter 9

How to Optimize Performance when using ACLs

9-32
FORE (Fast Out-of-Band Routing Engine): When an 80-series
Ethernet media module is not licensed for routing, the media
modules forward all routed packets to the supervisor. The F-
Chip on the supervisor module provides fast, direct forwarding
of L3 packets to their destination ports.
Hash Mode: The F-chip uses a 12-bit key to initially locate
available memory for Flows. In DA-only mode (default) it builds
the key from a sample of the Flow's destination address (DA). In
SA-DA mode, it uses both the source and destination addresses.
The F-chip automatically selects which 12 bits to use, and when
to re-hash with a different key.
Ingress F-chip: The F-chip that receives a packet from an
external source.
Layer 3 Forwarding Entry (L3FE): When a packet arrives on a
media module, the F-Chip needs to know where to forward
that packet. The L3 forwarding cache is a list that identifies the
path taken by a data packet through the switch. Each entry in
this list is a L3FE. Each entry is identified by a combination of the
Flow's 5-tuple and the corresponding ACL rule. If the F-chip
does not find a match in the L3 forwarding cache, the packet is
sent Slow Path to the CPU for processing and forwarding. Once
the CPU has determined the destination, it updates the L3
forwarding cache on the F-chips with the L3FE. Once updated,
the F-chip can forward future packets via Fast Path.
SA: Source IP Address.
Slow Path: When an ingress F-chip does not recognize a
packet compared to its cache of known Flows, the packet is
forwarded to the CPU to determine proper destination and ACL
Rule assignment. See Layer 3 Forwarding Entry.
There are several techniques to optimize performance. They are
related and must be considered together.
Recognize Performance Issues
Evaluate System Performance
Enable Routing at the Module
Design Safe, Efficient ACLs
Identify the Ports
Configure Hash Mode
Avaya P550R, P580, P880, and P882 Multiservice Switch User Guide, v5.3.1