New Training: Advanced IS-IS Foundations

In this 10-video skill, CBT Nuggets trainer Knox Hutchinson explores deeper theoretical understandings of IS-IS on Junos devices. Watch this new Juniper training.

Learn Juniper with one of these courses:

• Service Provider Routing and Switching Professional
• Advanced Juniper Routing Protocols
• Juniper IS-IS

This training includes:

• 10 videos
• 1.4 hours of training

You’ll learn these topics in this skill:

• Introducing Advanced IS-IS Foundation
• Multi-Level IS-IS Refresher
• IS-IS Packet Types
• Basic Multi-Level IS-IS Deployment on JUNOS
• LSPDU Contents and Common TLVs
• PDU Flooding and Mesh Groups
• Metric Tuning
• Validating IS-IS Config and LSDB
• Hierarchical Authentication
• Summarizing Advanced IS-IS Foundations

What is An IS-IS Hello Packet?

IS-IS is an interior gateway protocol (IGP) available on Juniper networking equipment. Much like OSPF, it's a link-state-based IGP. It's preferred over OSPF due to its inherent security and modularity, though. Likewise, much like OSPF, it uses something called a 'Hello' packet for discovery.

A 'Hello' packet is a broadcast packet used to discover the identity of neighboring networking devices. It uses these packets to determine if other devices are level 1 or level 2 intermediate devices.

These 'Hello' packets come in three forms:

• Point-to-Point hello packets
• Level 1 broadcast links
• Level 2 broadcast links

It should be noted that level 1 routers have to share the same area address to form an adjacency. Level 2 routers do not have that limitation.

The length of each 'Hello' packet is preset. IS-IS routers do not resize these packets. Instead, each interface supports the maximum packet size of 1492 bytes. Packets are padded to meet this size.