Anycast RP with MSDP and Static RP

 

I'm trying to apply my multicast studies to my work environment and have a scenario I'd like some input on.  

I want to transition a very critical clinical application off of a single static RP configuration to an Anycast RP setup.  What I need to know is can I have a single multicast group use two different RPs without any issues? I'm hoping I can point the application's multicast group at the new Anycast RP during a maintenance window and then gracefully remove the static RP without much issue.

Im my example the two MSDP peers are the core/distribution routers (6513) in a typical HSRP core/distribution/access setup.  The existing single static RP is one of the core routers and the Anycast RP would be on both core routers.  

In addition, this centralized multicast application is shared across a BGP routed dual-provider Metro-E setup so I'd like to not break this app for several hospitals but I really want some redundancy. 

 

 

 

 

Comments

  • Hi,

    Are you going to change the IP Address of the RP or will you use the one that is already statically configured?

    If you have all your static mappings with ip pim rp-address (without override command) then you can use BSR to advertise the new RP address, as the dynamic advertisements will be preferred over the static ones. At this step all your branch offices will pointo the new RP address. If you have the override option configured, then you will need to tweak it a little bit.

    Please let me know how your scenario is laid out and if you plan to keep the same IP or change it to a new one.

    HTH

    Good luck!

  • The main pitfall of Anycast is making sure the address you use for Anycast (typically a loopback but not necessarily so) is not used as a router-id.  Check that your router-id's for BGP, OSPF, MPLS, EIGRP etc are hard coded on these devices or you may find a reboot some time down the road causes you a big network outage.

     

    It is fine to share a single group accross multiple Anycast RP's aslong as MSDP is configured between the devices.  Sourcee and receivers will always register with their closest RP and MSDP will signal the other RPs that it has an active source.  If the other RPs have clients they will build a S,G tree to the source so the clients can receive the stream.  The leaf routers can then switchover to an S,G tree and bypass the RP(s).

     

    Just make absolutly sure that the Anycast address is not used as a Router-ID.  If you do not hard code your router-id's the routers could end up choosing the Anycast address as the router-id on the next reboot (if it happens to be the highest loopback) and then you will be in a "world of pain"

     

    Nick

     

  • The current single static RP and the Anycast RP are two different loopbacks.  The new anycast RP is not used as an OSPF/BGP router-id anywhere.  The two core 6513s I'm using are MSDP peers. 

    Looking at the sample config below, I want to add the 232.11.x.x group to the HUBSITE-ANYCAST ACL but not remove it form the STATIC-RP ACL.  The intent is to allow a smooth transition to the new anycast RP and then remove the old single RP.  

     

    NEW:

    ip access-list standard HUBSITE-ANYCAST

     REMARK PUSH TO TALK APP

     permit 232.16.x.x

     REMARK 

    ip pim rp-address 10.201.255.x HUBSITE-ANYCAST

     

    OLD:

    ip access-list standard STATIC-RP

     REMARK CLINICAL APP

     permit 232.11.x.x 0.0.0.255

    ip pim rp-address 10.201.252.x STATIC-RP

  • You can have the group in both ACL's but the router will use the RP with the highest IP address as the RP if there is more than one RP.  This would be the same for Static or Auto RP.  BSR allows a priority value to determine the RP.

     

    Nick

     

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