Solution Needed - BGP / MPLS / MULTICAST

ccie1yrccie1yr Member Posts: 19 ■□□□□□□□□□
in CCIE
I would like to get solution for below mentioned problem, any help in this regard would be very appreciated.

R1
|
|
C1
| MPLS |
R2
|
|
C2

R1 & R2 are HUB end routers and C1 & C2 are client routers. There is a BGP peering between R1, R2, C1 and C2 with Telco PE routers. Because, Telco doesn't allow multicast over MPLS network, there are GRE tunnel between;

R1-C1
R1-C2
R2-C1
R2-C2
Static routes have been configured to pass all interesting traffic (TCP & Multicast) through GRE tunnel only.

QUestion:
1. How to achieve automatic load balancing between tunnels when either BGP or Interface is down at either (HUB or CLIENT) end. (I am able to achieve this through IP SLA, but looking if there is any other better way of doing it).
2. As GRE tunnel are used for multicast, command IP MROUTE is also configured for packets to pass the RPF check. Would like to know how to achieve redundancy for MROUTE routes? So, if R1 interface fails how can I configure C's router to automatically move MROUTE routes through other tunnel?
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Comments

  • ColbyGColbyG Member Posts: 1,264
    Run a routing protocol across the tunnels instead of using static routes.
    http://blog.alwaysthenetwork.com
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  • chrisonechrisone Member Posts: 2,278 ■■■■■■■■■□
    eigrp , best "routing IGP" protocol! icon_thumright.gif
    Certs: CISSP, EnCE, OSCP, CRTP, eCTHPv2, eCPPT, eCIR, LFCS, CEH, SPLK-1002, SC-200, SC-300, AZ-900, AZ-500, VHL:Advanced+
    2023 Cert Goals: SC-100, eCPTX
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  • ccie1yrccie1yr Member Posts: 19 ■□□□□□□□□□
    Thanks, but EIGRP will solve only the first question.

    Does anyone have any suggestion about the second question?
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  • burbankmarcburbankmarc Member Posts: 460
    as long as PIM is enabled on your tunnel interfaces shouldn't the multicast just use your routing table to decide where to go. So the EIGRP through the tunnel fix should solve both your problems.
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  • ccie1yrccie1yr Member Posts: 19 ■□□□□□□□□□
    burbankmarc wrote: »
    as long as PIM is enabled on your tunnel interfaces shouldn't the multicast just use your routing table to decide where to go. So the EIGRP through the tunnel fix should solve both your problems.

    Nope, because IP MROUTE command is used to perform RPF check, which is the first step / check in multicast flowing. If RPF check fails multicast will not flow in that segment.

    In this case, RPF check will be performed and router will be expecting multicast to come through Tunnel interface, hence we configure IP MROUTE <Server_IP> <Tunnel Interface>. But when failover to other tunnel happen this static command will not alter and RPF check will fail.
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  • burbankmarcburbankmarc Member Posts: 460
    ccie1yr wrote: »
    Nope, because IP MROUTE command is used to perform RPF check, which is the first step / check in multicast flowing. If RPF check fails multicast will not flow in that segment.

    In this case, RPF check will be performed and router will be expecting multicast to come through Tunnel interface, hence we configure IP MROUTE <Server_IP> <Tunnel Interface>. But when failover to other tunnel happen this static command will not alter and RPF check will fail.

    Right, but if your IGP can handle all the pertinent routes then there's no need for the MROUTE.
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  • ccie1yrccie1yr Member Posts: 19 ■□□□□□□□□□
    burbankmarc wrote: »
    Right, but if your IGP can handle all the pertinent routes then there's no need for the MROUTE.

    Not quite sure, let me test it. I still believe that MROUTE is required for multicast to work, as it's used for RPF rather than routing.
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  • burbankmarcburbankmarc Member Posts: 460
    ccie1yr wrote: »
    Not quite sure, let me test it. I still believe that MROUTE is required for multicast to work, as it's used for RPF rather than routing.

    MROUTE is only needed when the RPF can't find the network in your routing table.
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  • networker050184networker050184 Mod Posts: 11,962 Mod
    burbankmarc wrote: »
    MROUTE is only needed when the RPF can't find the network in your routing table.

    I'm no multicast expert, but that is my understanding as well. The mroute is there only to override the routing table.
    An expert is a man who has made all the mistakes which can be made.
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  • ccie1yrccie1yr Member Posts: 19 ■□□□□□□□□□
    burbankmarc wrote: »
    MROUTE is only needed when the RPF can't find the network in your routing table.

    Hey buddy, thanks you are right.

    Configuration works without MROUTE command. Thanks, now I'll be able to configure this network with resiliency.
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  • livenliven Member Posts: 918
    burbankmarc wrote: »
    MROUTE is only needed when the RPF can't find the network in your routing table.

    Nice one man!
    encrypt the encryption, never mind my brain hurts.
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