Ericsson ECN330, User Manual

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Configuring the ECN330-switch
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1553-KDU 137 365 Uen D 2006-06-16
Note: The current root port and current root cost display as zero when this
device is not connected to the network.
6.10.2 Configuring Global Settings
Global settings apply to the entire ECN330-switch.
Command Usage
• Spanning Tree Protocol
Uses RSTP for the internal state machine, but sends only 802.1D
BPDUs. This creates one spanning tree instance for the entire network.
If multiple VLANs are implemented on a network, the path between
specific VLAN members may be inadvertently disabled to prevent
network loops, thus isolating group members. When operating multiple
VLANs, it is recommended to select the MSTP option.
• Rapid Spanning Tree Protocol
RSTP supports connections to either STP or RSTP nodes by
monitoring the incoming protocol messages and dynamically adjusting
the type of protocol messages the RSTP node transmits, as described
below:
• STP Mode – If the ECN330-switch receives an 802.1D BPDU (STP
BPDU) after a port’s migration delay timer expires, the ECN330-
switch assumes it is connected to an 802.1D bridge and starts using
only 802.1D BPDUs.
• RSTP Mode – If RSTP is using 802.1D BPDUs on a port and
receives an RSTP BPDU after the migration delay expires, RSTP
restarts the migration delay timer and begins using RSTP BPDUs
on that port.
• Multiple Spanning Tree Protocol
• To allow multiple spanning trees to operate over the network,
configure a related set of bridges with the same MSTP
configuration, allowing them to participate in a specific set of
spanning tree instances.
• A spanning tree instance can exist only on bridges that have
compatible VLAN instance assignments.