Interconnection of the STP and PVST

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As is known, Cisco switch supports the private STP protocol called PVST/PVST+/RPVST+, and it’s a tough task to interconnect the Huawei switch and Cisco switch as expected. The most main reason for that is the difference of BPDU packets between PVST and RSTP. To avoid that, Huawei launchs the similar protocol called VBST to make the interconnection easily.

In this post, we are going to introduce the sending PVST packets in different interface types.


Interface type
Cisco configuratio
Sending packets

Trunk

vlan 1 and vlan 10, 20 are allowed on the interface

interface GigabitEthernet0/1

switchport trunk allowed vlan 1,10,20

switchport mode trunk

Two types of BPDU packets will be sent on vlan 1, the standard STP packet and PVST packet. Since the vlan 1 is the default vlan, the pakcets of the standard STP packets wouldn’t carry the vlan tag.

PVST packets will be sent on other vlans.

Standard STP packet

PVST packet in vlan 1(untagged)

PVST packet in vlan 10(tagged)

PVST packet in vlan 20(tagged)

Trunk

vlan 1, 10 and 20 are allowed on the interface, the default vlan is configured to vlan 10.

interface GigabitEthernet0/1

switchport trunk native vlan 10

switchport trunk allowed vlan 1,10,20

switchport mode trunk
Two types of BPDU packets will be sent on vlan 1, the standard STP packet and tagged PVST packet.

Standard STP packet

PVST packet in vlan 1(tagged)

PVST packet in vlan 10(untagged)

PVST packet in vlan 20(tagged)

Trunk

vlan 1, 10 and 20 are allowed on the interface, disable the spanning-tree on vlan 1

no spanning-tree vlan 1

interface GigabitEthernet0/1

switchport trunk allowed vlan 1,10,20

switchport mode trunk
PVST function is disabled on vlan1, so no more PVST packets will be sent on vlan 1, but the standard STP packet keeps sending on vlan1

Standard STP packet

PVST packet in vlan 10(untagged)

PVST packet in vlan 20(tagged)

Trunk

vlan 1 is blocked on the interface

interface GigabitEthernet0/1

switchport trunk allowed vlan 10,20

switchport mode trunk
The standard STP packets wouldn’t send on vlan 1 anymore

PVST packet in vlan 10(untagged)

PVST packet in vlan 20(tagged)
Access

interface GigabitEthernet0/1

switchport acces vlan x

switchport mode acces
Only the standard STP pacekts are sent.Standard STP packet


From the graph, precondition for Cisco switch to send the standard STP packet is allowing vlan 1 in the trunk port or configuring the interface as an access port.


  • x
  • convention:

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