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Same IP address for 2 or more PEs

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  • 1.  Same IP address for 2 or more PEs

    Posted 09-16-2019 01:26

    IT is possible to configure more than one MX to behave like in the scenario described in the link:

     

    https://community.cisco.com/t5/mpls/same-ip-addresses-in-different-pes/td-p/823863

     

    Regards.



  • 2.  RE: Same IP address for 2 or more PEs
    Best Answer

    Posted 09-16-2019 02:05

    Hello,

    Yes, this is supported.

    You need to use LDP egress-policy to filter these IP from LDP

    https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/egress-policy-edit-protocols-ldp.html

    BUT - DON'T make this shared IP the router-id, use some other unique IP for router-id role.

    HTH

    Thx
    Alex



  • 3.  RE: Same IP address for 2 or more PEs

    Posted 09-16-2019 03:52

    hello, thank you for your answer.

    If i will not apply the egress-policy will the conexion still work, will there be log messages ?

     

    regards.



  • 4.  RE: Same IP address for 2 or more PEs

    Posted 09-16-2019 04:54

    Hello,

     


    @rocketfkinscience wrote:

    hello, thank you for your answer.

    If i will not apply the egress-policy will the conexion still work, will there be log messages ?

    Please define what do You mean by "conexion" (presumably "connection").

    If You mean TCP session towards this shared address then yes, it will work but the TCP client won't get to choose where it is connecting to: it will be always connecting to the closest node with that anycast IP.

    The best practice is to have 2 IP addresses on lo0.0: one unique which also serves as router-id, and second shared/anycast, which is only redistributed into IGP since MPLS anycast is quite rare technology and really is developed in the context of Segment Routing.

    If You have a mixed network with CSCO routers, then JUNOS egress policy is pretty much required to avoid the messages cited in CSCO support forums link.

    HTH

    Thx

    Alex