Multiple Spanning Tree - Motorola RFS Series Reference Manual

4-140 Motorola RF Switch System Reference Guide
1. Select Network Setup
2. Click the AP Firmware
3. Select an AP Image Type
4. Click the Edit
5. Modify the AP Image Type
6. Modify the AP Image File
AP images must be on the flash, system, nvram or usb filesystems in order for them to be selected.
7. Click the OK
8.

4.10 Multiple Spanning Tree

Multiple Spanning Tree Protocol (MSTP) provides a VLAN-aware protocol and algorithm to create and
maintain a loop-free network. It allows the configuration of multiple spanning tree instances. This ensures
a loop-free topology for 1 or more VLANs. It allows the network administrator to provide a different path for
each group of VLANs to better utilize redundancy.
MSTP allows rapid convergence similar to Rapid Spanning Tree Protocol (RSTP). RSPT is an independent
protocol and MSTP does not use RSTP. Since MSTP allows VLANs to be grouped in an instance, each
instance can have its own spanning-tree topology independent of other spanning-tree instances. This
architecture provides multiple forwarding links for data traffic, load balancing and therefore, reduces the
number of spanning-tree instances required to support a large number of VLANs.
Using MSTP, the network can be divided into regions. All switches within a region use the same VLAN to
instance mapping. The entire network runs a spanning tree instance called the Common Spanning Tree
instance (CST) that interconnects regions as well as legacy (STP and RSTP) bridges. The regions run on a local
instance for each configured MSTP instance.
The network-wide spanning tree for instance 0 is known as the Common Spanning Tree (CST). A spanning
tree for any other instance, which is local to a region, is known as an Internal Spanning Tree (IST). The
Common and Internal Spanning Tree (CIST) (which consists of the CST as well as all ISTs across regions)
interconnects all bridges in the network.
The following definitions describe the STP instances that define an MSTP configuration:
• Common Spanning Tree (CST) – MSTP runs a single spanning tree instance (called the Common Spanning
Tree) that interconnects all the bridges in a network. This instance treats each region as a single bridge.
In all other ways, it operates exactly like Rapid Spanning Tree (RSTP).
> Access Port
tab.
from the AP Image Upload
button to display a screen to change the
as necessary.
as necessary. You can browse the switch filesystems using the browser icon.
button to save the changes and return to the
from the main menu tree.
table.
AP Image Type
AP Firmware
or AP Image File.
tab.