Junos OS

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  • 1.  MPLS VPN COS in Service Provider

    Posted 03-08-2023 09:03

    Hi Guys,

    This is related to MPLS Service provider's Qos. As far as I know, when there is no Qos configured on the PE/P routers the default Qos takes care of CE to CE marking well. 

    If I want to participate CE to CE Qos, EXP classifiers and re-write can take care of copying CE DSCP markings and carrying till last P router (LSR) but pops marking and send customer marking without modification.

    In Cisco we have an option called qos-group to map EXP to qos-group and carrying from P router (PHP) to egress PE. Is there any option in Juniper MX where we can carry marking till egress PE. I think in Junos we can use DSCP re-write on PHP router interface so that markings are copied down to VPN label EXP and to CE.

    Need a correct direction in this case and if possible configuration/design doc.

    Thank you.



  • 2.  RE: MPLS VPN COS in Service Provider

    Posted 03-09-2023 06:44

    Cisco's QoS group does not survive forwarding - its scope is limited to the device on which is it set/read.  So on the wire Cisco and Juniper face the same challenges.  From memory JunOS does no rewriting of the customer traffic by default, however you can copy the customer IPP or CS part of the DSCP bits down to the MPLS EXP bits.  Assuming we're talking VPNs, from ingress PE to the penultimate hop (P) there are TWO labels, and by default from the penultimate hop (P) to the egress PE there will be one (the VPN label).  So at this point you still have the MPLS EXP on which to classify, and the encapsulated customer traffic. 

    Not sure if this helps :)