H3C Technologies H3C S10500 Series Switches - Manual (Page 76)

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Device Comparison process
Configuration BPDU on
ports after comparison
• Device B compares the configuration BPDUs of all its ports,
decides that the configuration BPDU of Port B1 is the optimum,
and selects Port B1 as the root port with the configuration BPDU
unchanged.
• Based on the configuration BPDU and path cost of the root port,
Device B calculates a designated port configuration BPDU for
Port B2 {0, 5, 1, Port B2}, and compares it with the existing
configuration BPDU of Port B2 {1, 0, 1, Port B2}. Device B finds
that the calculated one is superior, decides that Port B2 is the
designated port, replaces the configuration BPDU on Port B2
with the calculated one, and periodically sends the calculated
configuration BPDU.
• Root port (Port B1): {0,
0, 0, Port A1}
• Designated port (Port
B2): {0, 5, 1, Port B2}
• Port C1 receives the configuration BPDU of Port A2 {0, 0, 0, Port
A2}, finds that the received configuration BPDU is superior to its
existing configuration BPDU {2, 0, 2, Port C1}, and updates its
configuration BPDU.
• Port C2 receives the original configuration BPDU of Port B2 {1,
0, 1, Port B2}, finds that the received configuration BPDU is
superior to the existing configuration BPDU {2, 0, 2, Port C2},
and updates its configuration BPDU.
• Port C1: {0, 0, 0, Port
A2}
• Port C2: {1, 0, 1, Port
B2}
• Device C compares the configuration BPDUs of all its ports,
decides that the configuration BPDU of Port C1 is the optimum,
and selects Port C1 as the root port with the configuration BPDU
unchanged.
• Based on the configuration BPDU and path cost of the root port,
Device C calculates the configuration BPDU of Port C2 {0, 10, 2,
Port C2}, and compares it with the existing configuration BPDU
of Port C2 {1, 0, 1, Port B2}. Device C finds that the calculated
configuration BPDU is superior to the existing one, selects Port
C2 as the designated port, and replaces the configuration
BPDU of Port C2 with the calculated one.
• Root port (Port C1): {0,
0, 0, Port A2}
• Designated port (Port
C2): {0, 10, 2, Port C2}
Device C
• Port C2 receives the updated configuration BPDU of Port B2 {0,
5, 1, Port B2}, finds that the received configuration BPDU is
superior to its existing configuration BPDU {0, 10, 2, Port C2},
and updates its configuration BPDU.
• Port C1 receives a periodic configuration BPDU {0, 0, 0, Port
A2} from Port A2, finds that it is the same as the existing
configuration BPDU, and discards the received one.
• Port C1: {0, 0, 0, Port
A2}
• Port C2: {0, 5, 1, Port
B2}