Mstp; Mstp Concepts - 3Com 7700 Configuration Manual

222 C 8: STP O
HAPTER PERATION

MSTP

MSTP Concepts

3 Configure the ports (Ethernet 0/1 through Ethernet 0/24) directly connected to
users as edge ports and enable BPDU PROTECTION function. (Take Ethernet 0/1 as
an example.)
[SW7700] interface ethernet 0/1
[SW7700-Ethernet0/1] stp edged-port enable
[SW7700] stp bpdu-protection
4 RSTP operating mode, time parameters, and port parameters take default values.
The Switch 7700 implements the Multiple Spanning Tree Protocol (MSTP), which is
an enhancement to STP, and is compatible with both STP and RSTP. However, a
single switch cannot support both MSTP and RSTP. An MSTP switch can recognize
both STP and RSTP packets and can calculate the spanning tree with them. Beside
the basic MSTP functions, the Switch 7700 provides additional features which
include root bridge hold, secondary root bridge, root protection, BPDU protection,
protocol hot swapping, and master/slave switchover.
STP cannot transmit rapidly. Even on the point-to-point link or the edge port, it
must take an interval as long as twice the forward delay before the network
converges.
MSTP makes the network converge rapidly and distributes the traffic of different
VLANs along their respective paths, which provides a better load-balance
mechanism for the redundant links.
MSTP associates VLAN and the spanning tree and divides a switching network into
several regions, each of which has a spanning tree independent of one another.
MSTP prunes the network into a loopfree tree to avoid proliferation, it also
provides multiple redundant paths for data forwarding to implement the VLAN
data forwarding load-balance.
There are 4 MST regions in Figure 5.
Figure 5 MSTP Concepts
MST Region
A multiple spanning tree region contains several physically and directly connected
MSTP switches sharing the same region name, VLAN-spanning tree mapping
configuration, and MSTP revision level configuration, and the network segments
between them. There can be several MST regions on a switching network. You can