IS-IS supports 2 network types – Broadcast link and P2P link. By default, Ethernet port on the routers will regards as a broadcast link. However after details study, all links in this IPRAN network are point-to-point connected. Therefore it is recommended that the circuit type for ISIS is defined as p2p. On a point-to-point link, Complete Sequence Network Packet (CSNP) only needs to be sent when the neighbor relationship is established the first time. This reduces the frequency of the unnecessary periodic CSNP sent by DR. In addition p2p will also enhance the speed of convergence