The root bridge should be
located in the center of your network traf?¬?c ?¬‚ow.
Rapid Spanning Tree Protocol
Rapid Spanning Tree Protocol (RSTP), speci?¬?ed in the IEEE 802.1w standard, supersedes
STP as speci?¬?ed in 802.1D, while remaining compatible with STP. RSTP can be seen as an
evolution of the 802.1D standard rather than a revolution. The 802.1D terminology remains
primarily the same. Most parameters have been left unchanged, so users familiar with
802.1D can con?¬?gure the new protocol comfortably.
Bridge ID Without the
Extended System ID
Bridge ID = 8 Bytes
Bridge ID = 8 Bytes
Bridge
Priority
Bridge
Priority
Extend
System ID
MAC Address
MAC Address
2 Bytes 6 Bytes
Extended Bridge ID
with System ID
System ID = VLAN
4 Bits 12 Bits 48 Bits
Improving Performance with Spanning Tree 59
RSTP signi?¬?cantly reduces the time to reconverge the active topology of the network when
changes to the physical topology or its con?¬?guration parameters occur. RSTP de?¬?nes the
additional port roles of alternate and backup, and it de?¬?nes port states as discarding,
learning, or forwarding.
RSTP selects one switch as the root of a spanning-tree active topology and assigns port
roles to individual ports on the switch, depending on whether the ports are part of the active
topology.
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