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
Chapter 9: Spanning tree
Spanning tree prevents loops in switched networks. Virtual Services Platform 4000 supports Rapid
Spanning Tree Protocol (RSTP) and Multiple Spanning Tree Protocol (MSTP). This section describes
issues to consider when you configure spanning tree protocols.
For more information about spanning tree protocols, see Avaya Virtual Services Platform 4000
Configuration — VLANs and Spanning Tree, NN46251-500.
Spanning tree and protection against isolated VLANs
Virtual Local Area Network (VLAN) isolation disrupts packet forwarding.
Figure 13: VLAN
isolation on page 52 shows the problem. Two VLANs (V1 and V2) connect four devices, and
both VLANs are in the same STG. V2 includes three of the four devices, whereas V1 includes
all four devices. After a spanning tree protocol detects a loop, it blocks the link with the highest
link cost. In this case, the 100 Mbit/s link is blocked, which isolates a device in V2. To avoid
this problem, either configure V2 on all four devices or use MSTP with a different Multiple
Spanning Tree Instance (MSTI) for each VLAN.
Network Design Reference for Avaya VSP 4000 February 2014 51