Configuration Guide
Table Of Contents
- Notice
- Documentation disclaimer
- Link disclaimer
- Warranty
- Hosted Service
- Licenses
- License type(s)
- Copyright
- Virtualization
- Third Party Components
- Service Provider
- Compliance with Laws
- Preventing Toll Fraud
- Security Vulnerabilities
- Downloading Documentation
- Contact Extreme Networks Support
- Contact Avaya Support
- Trademarks
- Figures
- Tables
- 1. Overview
- 2. Supported Topologies and Releases
- 2.1 Single Layer 2 Switch
- 2.2 Centralized Layer 3 Stackable Switch
- 2.3 Single Layer 3 Modular Switch
- 2.4 Switch Clustering Topologies
- 2.4.1 Switch Clustering – Topology 1
- 2.4.2 Switch Clustering – Topology 2
- 2.4.3 Switch Clustering – Topology 3
- 2.4.4 Switch Clustering – Topology 4
- 2.4.5 Switch Clustering – Topology 5
- 2.4.6 Switch Clustering Configuration Examples
- 3. Appendix
- 4. Software Baseline
- 5. Reference Documentation
©2020 Extreme Networks, Inc. All rights reserved
November 2020
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Frames from clients are forwarded to the clusters virtual IP address with a destination MAC address set
to the clusters virtual multicast MAC address. Depending on the multicast mode, the frames are ether
flooded to all ports in the broadcast domain or forwarded to only the ports that the cluster hosts are
connected to.
Figure 1.2.2-4 – IGMP-Multicast Traffic Flow
1.3 Load Balancing Algorithm
Network Load Balancing employs a fully distributed filtering algorithm to map incoming clients to the
cluster hosts. The distributed algorithm enables cluster hosts to make load-balancing decisions
independently and quickly for each incoming packet. The distributed algorithm is optimized to statistically
load balance traffic for large client populations and is less effective when the client population is small or
the client connections produce widely varying loads on the server.
Network Load Balancing balances incoming client requests by directing a selected percentage of new
requests to each cluster host. The algorithm does not respond to changes in the load on each cluster
host (such as the CPU load or memory usage). However, the mapping is modified when the cluster
membership changes, and load percentages are renormalized accordingly.
When inspecting an arriving packet, all cluster hosts simultaneously perform a statistical mapping to
quickly determine which host should handle the packet. The mapping uses a randomization function that
calculates a host priority based on the client's IP address, port, and other state information. The
corresponding host forwards the packet up the network stack to TCP/IP, and the other cluster hosts
discard it. The mapping does not vary unless the membership of cluster hosts changes, ensuring that a
given client's IP address and port will always map to the same cluster host. The particular cluster host to
which the client's IP address and port map cannot be predetermined since the randomization function
takes into account the current and past cluster's membership to minimize re-mappings.