IS-IS
Overview
Link-state, uses Dijkstra algorithm
Router Types
Level 1: intra-area (can only form relationships with other Level 1 routers).
Level 2: inter-area (can only form relationships with other Level 2 routers).
Level 1-2: both.
Routing
Level 1 ↔ Level 1
Level 2 ↔ Level 2
Level 1 ↔ Level 1-2 ↔ Level 2
Other Stuff
Area borders are between routers (i.e. on the link) in contrast to OSPF where the area border is within an ABR.
Useful Articles
Running IS-IS over unnumbered Ethernet interfaces. [ipSpace]
IS-IS flooding details. [ipSpace]
LSA/LSP flooding in OSPF and IS-IS. [ipSpace]
Digging deep into IS-IS. [Network Collective]
RFC 8202: IS-IS multi-instance. [Russ White]
IS-IS for IPv6. [ipCisco]
Configuration example on Cisco IOS. [ipCisco]
IS-IS configuration example on Cisco IOS. [ipCisco]
Demystifying the IS-IS database. [MellowD]
Junos day one: IS-IS for dummies. [ipSpace]
Multi-level IS-IS in a single area? Think again! [ipSpace]
Multi-topology IS-IS. [IOS Hints]
Basics of IS-IS. [MPLS VPN]
© Robert Larsen. All rights reserved.