9. ISIS in Broadcast Network and Pseudonode LSP

ISIS in broadcast network is the topic of this section.
In the previous section we have seen that in ISIS routing protocol, each router advertises exactly one LSP to advertise its IP and topology information. On the broadcast network, there is an additional LSP with the name of pseudonode LSP which is advertised by DIS.
In this section we will discuss how psudonode LSP reduces the overhead of the ISIS database exchange process.

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8. ISIS LSP Types and Database Exchange

ISIS LSP types and database exchange detail is what we discuss after adjacency comes up in ISIS and it is the topic of this section.
To better understand database exchange process in ISIS routing protocol, we will compare ISIS packets with OSPF packets, ISIS LSP types with OSPF LSA types and finally we will have a configuration example to demonstrate ISIS LSP packet details.

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7. ISIS Adjacency Fundamental

ISIS Adjacency details are the first step to learn not only the ISIS routing protocol but all other routing protocols, which is discussed in this section.
We will discuss L1 and L2 Adjacency. ISIS Adjacency Differences in LAN and Point-to-Point Interfaces. Adjacency Timers, ISIS Adjacency requirements and also ISIS Adjacency States which help us in troubleshooting.

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4. ISIS NET Address Format

ISIS NET Address is what we have to configure when we use ISIS routing protocol in the network.
This is because the ISIS protocol was originally developed for CLNS networks. Although we use ISIS to route IP traffic, but ISIS control packets still use CLNS address to communicate with each other.
ISIS NET address is a type of CLNS address that we will discuss in this section.

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