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New Member

Mapping bridge priority to vlan id

Dear All,

in per vlan spanning tree (PVST) each vlan can have differnet bridge priority,

my question is without mac address reduction how swtich can map each priority to vlan id in bpdus received

thanks

  • LAN Switching and Routing
1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Mapping bridge priority to vlan id

Hi,

without mac address reduction how swtich can map each priority to vlan id in bpdus received

PVST+ BPDUs are 802.1Q-tagged by their appropriate VLAN they belong to. Upon arrival, BPDUs are processed in their appropriate instance according to their 802.1Q tag. The extended system ID is never used to sort received BPDUs into appropriate VLANs (and thus STP instances) because the receiving device can not know whether the sender of the BPDU is using the MAC reduction or not.

Best regards,

Peter

2 REPLIES
Cisco Employee

Mapping bridge priority to vlan id

Hi,

without mac address reduction how swtich can map each priority to vlan id in bpdus received

PVST+ BPDUs are 802.1Q-tagged by their appropriate VLAN they belong to. Upon arrival, BPDUs are processed in their appropriate instance according to their 802.1Q tag. The extended system ID is never used to sort received BPDUs into appropriate VLANs (and thus STP instances) because the receiving device can not know whether the sender of the BPDU is using the MAC reduction or not.

Best regards,

Peter

New Member

Mapping bridge priority to vlan id

Dear Peter

thanks

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