User's Manual

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Edge Port
In RSTP and MSTP, the edge port means a port directly connecting the host, and is capable of entering the
forwarding state directly without waiting and loop.
Figure 2.7 Edge port
Originally, MSTP, including RSTP, regards all ports are edge ports and therefore the network topology can be
established swiftly. If a port in this case receives BPDU from another switch, the port will resume its edge state
from its normal state; if it receives 802.1D STP BPDU, it has to wait for double forward delays and then enters
its forwarding state.
36.1.5 MSTP BPDU
Similar to STP and RSTP, switches running MSTP can communicate with each otherthrough Bridge Protocol
Data Unit (BPDU). All configuration information about the CIST and MSTI can be carried by BPDU. Table 2.1
and Table 2.2 list the structure ofBPDU used by the MSTP.
Table 2.1 MSTP BPDU
Field Name Byte Number
Protocol Identifier 1 – 2
Protocol Version Identifier 3
BPDU Type 4
CIST Flags 5