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New Member

MPLS VPN - QoS fragmentation


we've and Hub and spoke VPN topology that use an MPLS network to connect branch office to HQ.

Branch-office LAN have IP gateway (Cisco 2611) which interconnect the PBX to IP network, and QoS is configured END-to-END both on customer private network, forcing DSCP value on voice traffic before entering the CPE, and on the MPLS ISP network, using DSCP and LLQ ....

The problem is that voice call are susceptible, and called people randomly don't hear the full conversation but only some parts...

I'm investigating and I've figure out QoS LLQ classes configured are respected but there is no LFI mechanism implemented ...

Anyone can give me some advice or had experienced similar problem ???


Re: MPLS VPN - QoS fragmentation

I have not had similar problems. But if you feel that implementing LFI will solve your problem, you can either use MLPPP or FRF.12 based on the encapsulation you use on your connection to the provider.

New Member

Re: MPLS VPN - QoS fragmentation


thanks for the info....the problem is that the connection to the Provider is based on Ethernet and there you can't use the mechanism of LFI.

Did you configure something special (payload of a voice packet, some special codec,...)??? I mean we use G729 with VAD, on internal LAN ToS configured for voice, on the VPN the ToS is mapped to DSCP which enter on ISP CPE and are treated with a LLQ mechanism based on DSCP...

In this situation, 80% of the time the voice is not fluently trasmitted but it's like a GSM that have intermittent coverageto with the antennas...