Reference Guide

608 | Multiple Spanning Tree Protocol (MSTP)
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Figure 32-1. MSTP with Three VLANs Mapped to Two Spanning Tree Instances
Dell Networking OS supports three other variations of Spanning Tree, as shown in Table 44.
Implementation Information
• The Dell Networking OS MSTP implementation is based on IEEE 802.1Q-2003, and interoperates
only with bridges that also use this standard implementation.
• MSTP is compatible with STP and RSTP.
• Dell Networking OS supports only one MSTP region.
• When you enable MSTP, all ports in Layer 2 mode participate in MSTP.
• On the S5000, you can configure 64 MSTIs including the default instance 0 (CIST).
Configuring Multiple Spanning Tree Protocol
Configuring Multiple Spanning Tree is a four-step process:
1. Configure interfaces for Layer 2. See page 761.
2. Place the interfaces in VLANs.
3. Enable Multiple Spanning Tree Protocol. See page 609.
Table 32-1. Dell Networking OS Supported Spanning Tree Protocols
Dell Networking Term IEEE Specification
Spanning Tree Protocol 802.1d
Rapid Spanning Tree Protocol 802.1w
Multiple Spanning Tree Protocol 802.1s
Per-VLAN Spanning Tree Plus Third Party
R1
R2
R3
1/21
3/11
3/21
1/31
2/11
2/31
MSTI 1 root
MSTI 1: VLAN 100
MSTI 2: VLAN 200, VLAN 300 MSTI 2: VLAN 200, VLAN 300
MSTI 2 root
Forwarding
Blocking