In an IS-IS point-to-point type network, the operation of link state database synchronization is slightly different from that in a broadcast network, and the industrial-grade full Netcom routers send CSNP and PSNP messages and their functions have some differences.

In a point-to-point network, there is no DIS. Industrial 3G routers do not periodically send CSNP packets. CSNP packets are sent only once when the link is activated, and industrial 4g routers at both ends of the link will send CSNPs. The message describes the summary information of all LSPs in the local link state database. When the industrial router sends a CSNP sent by the peer that contains locally missing LSP information, it also uses the PSNP packet to request the LSP from the peer. When the peer receives a PSNP message, it sends an LSP message containing the complete LSP information to the requester, which is the same as the operation in a broadcast network. However, on the point-to-point link, the industrial 4g router with ethernet that received the LSP message will also send a PSNP message to the other party to confirm the previously received LSP. It can be said that LSP exchange in a point-to-point network is reliable. This is different from a broadcast network. In a broadcast network, industrial wireless routers do not use PSNP messages to confirm received LSPs, but instead send CSNP messages periodically through DIS to compensate for unreliable LSP exchanges in broadcast networks.

On point-to-point links, industrial routers use PSNP to confirm received LSP packets, so they are a reliable flooding mechanism on point-to-point links.