MPLS Additions to IS-IS
IS-IS has been extended to support MPLS traffic engineering by including additional information about attached links in its link state packets. The additional information is carried in new TLVs and flooded to all intermediate systems within an area.
The Router ID TLV
The Router ID TLV is used to flood the router ID of each label switching device that originates an MPLS tunnel to all other intermediate systems within the area; the IP router ID should be the same as the OSPF and BGP router IDs if those protocols are configured on the intermediate system. The router ID is commonly used to provide a single next hop or forwarding address for all traffic being forwarded through an intermediate system—it is normally the address ...