IS-IS PDUs

IS-IS PDUs
Before we move on to the way routers flood LSPs, now would be a good time to have an
overview of the nine different types of IS-IS PDUs. There are three main categories that
IS-IS PDUs fall into:
 Hello PDU
 Link-state PDU (LSP)
 Sequence number PDU (SNP)
Each of the three main categories can be broken down into the actual PDUs used for that
category. Let’s look at each of these categories in more detail.