Design Reference
Table Of Contents
- Contents
- Chapter 1: Introduction
- Chapter 2: New in this release
- Chapter 3: Network design fundamentals
- Chapter 4: Hardware fundamentals and guidelines
- Chapter 5: Optical routing design
- Chapter 6: Platform redundancy
- Chapter 7: Link redundancy
- Chapter 8: Layer 2 loop prevention
- Chapter 9: Spanning tree
- Chapter 10: Layer 3 network design
- Chapter 11: SPBM design guidelines
- Chapter 12: IP multicast network design
- Multicast and VRF-Lite
- Multicast and MultiLink Trunking considerations
- Multicast scalability design rules
- IP multicast address range restrictions
- Multicast MAC address mapping considerations
- Dynamic multicast configuration changes
- IGMPv3 backward compatibility
- IGMP Layer 2 Querier
- TTL in IP multicast packets
- Multicast MAC filtering
- Guidelines for multicast access policies
- Multicast for multimedia
- Chapter 13: System and network stability and security
- Chapter 14: QoS design guidelines
- Chapter 15: Layer 1, 2, and 3 design examples
- Chapter 16: Software scaling capabilities
- Chapter 17: Supported standards, RFCs, and MIBs
- Glossary
propagation across the network if users change channels rapidly. Leave latency also depends on
the robustness value, so a value of 2 equates to a leave latency of twice the LMQI.
Determine the proper LMQI value for your particular network through testing. If a very large number
of users connect to a port, assigning a value of 3 can lead to a storm of report messages after a
group-specific query is sent. Conversely, if streams frequently start and stop in short intervals, as in
a TV delivery network, assigning a value of 10 can lead to frequent congestion in the core network.
Another performance-affecting factor that you need to be aware of is the error rate of the physical
medium. For links that have high packet loss, you can find it necessary to adjust the robustness
variable to a higher value to compensate for the possible loss of IGMP queries and reports.
In such cases, leave latency is adversely affected as numerous group-specific queries are
unanswered before the stream is pruned. The number of unanswered queries is equal to the
robustness variable (default 2). The assignment of a lower LMQI can counterbalance this effect.
However, if you configure the LMQI too low, it can actually exacerbate the problem by inducing
storms of reports on the network. LMQI values of 3 and 10, with a robustness value of 2, translate to
leave latencies of 6/10 of a second and 2 seconds, respectively.
When you choose an LMQI, consider all of these factors to determine the best configuration for the
given application and network. Test that value to ensure that it provides the best performance.
Important:
In networks that have only one user connected to each port, Avaya recommends that you use
the Fast Leave feature instead of LMQI, because no wait is required before the stream stops.
Similarly, the robustness variable does not affect the Fast Leave feature, which is an additional
benefit for links with high loss.
Multicast for multimedia
January 2015 Network Design Reference for Avaya VSP 4000 Series 115
Comments? infodev@avaya.com