| Intermediate System Hello (ISH) packets are a type of a hello packet. ISH is part of the ES-IS spec 9542; similar to IRDP in TCP/IP; used for ISs and ESs to detect each other. ISH packets are sent out to all IS-IS-enabled interfaces. On LANs they are sent out periodically, destined to a special multicast address. Routers will become neighbors when they see themselves in their neighbor's hello packets and link authentication information matches. |