Huawei AR530 Series - Page 249

Table 7-6 lists the major information carried in an MST BPDU.
Table 7-6 Major information carried in an MST BPDU
Field Byte Description
Protocol
Identifier
2 Indicates the protocol identifier.
Protocol
Version
Identifier
1 Indicates the protocol version identifier. 0 indicates STP;
2 indicates RSTP; 3 indicates MSTP.
BPDU Type 1 Indicates the BPDU type:
l 0x00: Configuration BPDU for STP
l 0x80: TCN BPDU for STP
l 0x02: RST BPDU or MST BPDU
CIST Flags 1 Indicates the CIST flags.
CIST Root
Identifier
8 Indicates the CIST root switching device ID.
CIST External
Path Cost
4 Indicates the total path costs from the MST region where
the switching device resides to the MST region where the
CIST root switching device resides. This value is
calculated based on link bandwidth.
CIST Regional
Root Identifier
8 Indicates the ID of the regional root switching device on
the CIST, that is, the IST master ID. If the root is in this
region, the CIST Regional Root Identifier is the same as
the CIST Root Identifier.
CIST Port
Identifier
2 Indicates the ID of the designated port in the IST.
Message Age 2 Indicates the lifecycle of the BPDU.
Max Age 2 Indicates the maximum lifecycle of the BPDU. If the
Max Age timer expires, it is considered that the link to
the root fails.
Hello Time 2 Indicates the Hello timer value. The default value is 2
seconds.
Forward Delay 2 Indicates the forwarding delay timer. The default value
is 15 seconds.
Version 1
Length
1 Indicates the BPDUv1 length, which has a fixed value of
0.
Version 3
Length
2 Indicates the BPDUv3 length.
Huawei AR530&AR550 Series Industrial Switch Routers
Configuration Guide - Ethernet Switching 7 MSTP Configuration
Issue 01 (2014-11-30) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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