Quick question about router-id


If a router has EIGRP, OSPF and BGP running, will that cause any conflict/trouble to use a single loopback IP address (e.g. as the router-id for all three routing protocols?

Or it is recommended to use a different router-id for different routing protocol on the same router?



  • Nope.  Same router-id for all routing protocols is fine.

  • For the current R&S Lab Exam the only real requirement is that the router-id for each protocol be unique within that protocol - for BGP make sure no other router has the same BGP router-id, for OSPF make sure no other router has the same OSPF router-id, etc.

    For Service Provider it makes some things simpler to use the same router-id for all protocols that have to work together, such as OSPF, BGP and MPLS. It helps to have the BGP peering address and router-id be the same loopback IP, since MPLS will also form adjacencies using a loopback by default. This means that the loopback needs to be know via IGP for the MPLS adjacencies to become established. When MPLS becomes part of the R&S Lab Exam, this could be important for R&S, too.

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