Command Reference Guide

N8406-022A 1Gb Intelligent L2 Switch Command Reference Guide (AOS) 87
Rapid Spanning Tree Protocol / Multiple Spanning Tree Protocol
configuration
Command: /cfg/l2/mrst
[Multiple Spanning Tree Menu]
cist - Common and Internal Spanning Tree menu
name - Set MST region name
rev - Set revision level of this MST region
maxhop - Set Maximum Hop Count for MST (4 - 60)
mode - Spanning Tree Mode
on - Globally turns RSTP/MSTP ON
off - Globally turns RSTP/MSTP OFF
cur - Display current MST parameters
The switch supports the IEEE 802.1w Rapid Spanning Tree Protocol (RSTP) and IEEE 802.1s Multiple Spanning
Tree Protocol (MSTP). MSTP allows you to map many VLANs to a small number of spanning tree groups, each
with its own topology.
You can configure up to 31 spanning tree groups on the switch (STG 32 is reserved for switch management).
MRST is turned off by default.
NOTE: When Multiple Spanning Tree is turned on, VLAN 1 is moved from Spanning Tree Group 1 to the
Common Internal Spanning Tree (CIST). When Multiple Spanning Tree is turned off, VLAN 1 is moved back to
Spanning Tree Group 1.
The following table describes the Multiple Spanning Tree Configuration Menu options.
Table 86 Multiple Spanning Tree Configuration Menu options
Command
Description
cist
Displays the Common Internal Spanning Tree (CIST) Menu.
name <1-32 characters>
Configures a name for the MSTP region. All devices within a MSTP region
must have the same region name.
rev <0-65535>
Configures the revision level for the MSTP region. The revision level is used as
a numerical identifier for the region. All devices within a MSTP region must
have the same revision level number. The range is 0-65535.
maxhop <4-60>
Configures the maximum number of bridge hops a packet may to traverse
before it is dropped. The range is from 4 to 60 hops. The default is 20.
mode rstp|mstp
Selects either Rapid Spanning Tree mode (rstp) or Multiple Spanning Tree
mode (mstp). The default mode is RSTP.
on
Globally turn RSTP/MSTP ON.
Note: When RSTP is turned on, the configuration parameters for STP group 1
apply to RSTP
off
Globally turn RSTP/MSTP OFF. This is the default.
cur
Displays the current RSTP/MSTP configuration.
NOTE:
IEEE 802.1w standard-based RSTP implementation runs on one STG (i.e. same as one spanning tree
instance) only. As a result, if ‗rstp‘ mode is selected under the /cfg/mrst/mode command, then only a
single RSTP instance (default for STG 1) is supported for all VLANs, including the Default VLAN 1.
If multiple spanning tree instances are required, then select ‗mstp‘ mode so that multiple VLANs are
handled by multiple spanning tree instances, as specified by IEEE 802.1s standard-based MSTP
implementation.
IEEE 802.1s MSTP supports rapid convergence using IEEE 802.1w RSTP.
PVST+ does not support rapid convergence in current versions.
NOTE:
The following configurations are unsupported:
PVST+ (default Spanning Tree setting) is NOT interoperable with Cisco Rapid PVST+.
MSTP/RSTP (with mode set to either ‗mstp‘ or ‗rstp‘) is NOT interoperable with Cisco Rapid PVST+.
The following configurations are supported:
PVST+ (default Spanning Tree setting) is interoperable with Cisco PVST+.
MSTP/RSTP (with mode set to ‗mstp‘) is interoperable with Cisco MST/RSTP.