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New Member

Rapid Spanning Tree and VoIP Trunk Ports

Hello,

We have an Alcatel VoIP telephony platform, the handsets connect to switch ports configured as Trunk ports, with a dedicated Voice VLAN for the voice traffic.  The VoIP Handsets have a LAN interface to which the PC connects, the PC traffic is then carried over the native vlan on the trunk.

We are running Rapid PVST (RSTP) but everytime there is a topology change the PC/Phones lose conenctivity for the duration of tranditional 802.1d Spanning Tree.  We cannot enable portfast on the switch ports because they are trunk ports, even if we enable portfast it will not be active becuase the port is trunking, so the trunk port to the phone is seen as a STP P2P type port and not an Edge Type port.  When a topology change occurs it tries to use RSTP to synchronise but the VoIP phone does not undestand RSTP so it falls back to STP timers, taking apx 50 seconds to transist back to a forwarding state.  This causes the phones to reset etc. and an extended outage for the end user.

Is there any way round this??

Thanks

Ryan

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Blue

Re: Rapid Spanning Tree and VoIP Trunk Ports

Ryan

Have you tried using the "spanning-tree portfast trunk" command on the trunk ports to the VOIP phones ?

Jon

2 REPLIES
Hall of Fame Super Blue

Re: Rapid Spanning Tree and VoIP Trunk Ports

Ryan

Have you tried using the "spanning-tree portfast trunk" command on the trunk ports to the VOIP phones ?

Jon

New Member

Re: Rapid Spanning Tree and VoIP Trunk Ports

Genius,

Thank you very much Jon, this works!

Ryan

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