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The bpdu packet has not transparent lead to STP not become effective in transparent mode

Publication Date:  2012-09-25 Views:  736 Downloads:  0

Issue Description

User networking:
convergence switch-------usg5300----core switch
Phenomenon: network enable the STP, and firewall access the switch between convergence and core layer in transparent mode. Lead to convergence switch can't find the root of core switch, STP failure. After cancel the firewall STP it is normal.

Alarm Information


Handling Process

1, check the configuration and do not find error. Upstream is trunk, and allow the service vlan and management vlan pass.
2, grab bpdu packet to analysis, and do not take tag. Check the interface information find:
The Maximum Transmit Unit is 1500 bytes, Hold timer is 10 (SEC)
PVID: 1.
Port link - type: trunk
VLAN permitted: none
Media type is twisted pair, loopback is not set, promiscuous mode not set
1000 MB/s - speed mode, Half - duplex mode, link type is auto negotiation
Flow control is disable
The default pvid is 1
3, the firewall upstream/downstream interface of trunk interface allows vlan1 transparent, and STP is normal.

Root Cause

1, configuration error
2, do not support transparent bpdu packet
3, other


Suggestions and summarizes
Conclusion: bpdu packets don't bring tag by default. Because trunk interface default pvid is 1, packet attaches a tag as the number 1 after pass interface, and therefore must run vlan1 through. Because the switch runs vlan1 through by default, not like the FW, so don't need to configure the command that run vlan1 through.