UMN:CLI
User Manual
V8102
372
9.4.2.4
Compatibility with 802.1d
RSTP internally includes STP, so it has compatibility with 802.1d. Therefore, RSTP can
recognize the BPDU of STP. However, STP cannot recognize the BPDU of RSTP. For ex-
ample, assume that SWITCH A and SWITCH B are operated as RSTP and that SWITCH
A is connected to SWITCH C as the designated switch. If SWITCH C is with 802.1d ignor-
ing the BPDU of RSTP, it is interpreted as not connected to any switch or segment.
Fig. 9.30
Compatibility with 802.1d (1)
However, SWITCH A converts the port receiving BPDU into RSTP of 802.1d because it
can read the BPDU of SWITCH C. Then SWITCH C can read BPDU of SWITCH A and
accepts SWITCH A as the designated switch.
Fig. 9.31
Compatibility with 802.1d (2)
9.4.3
MSTP Operation
To operate the network more effectively, the V8102 uses MSTP (Multiple Spanning-Tree
Protocol). It constitutes the network with VLAN subdividing logically the existing LAN do-
main and configures the route by VLAN or VLAN group instead of existing routing proto-
col.
Operation
This section explains how STP/MSTP operate differently on the LAN. Suppose to config-
ure 100 VLANs in the switch A, B, and C.
In case of STP, there’s only an STP on all of
VLANs and it does not provide multiple Instances.