TOI Author

IS-IS LSP out-delay is a feature implemented to mitigate transient micro-loops that can occur during topology changes in an IS-IS network.When a topology change occurs (e.g., a link state or metric change), different routers in the network receive and process the updated Link State PDUs (LSPs) at slightly different times. This can lead to a transient state where some routers have updated their Forwarding Information Base (FIB) based on new LSPs, while others have not, causing traffic to be incorrectly forwarded and forming micro-loops.

EOS IS-IS implementation advertises interface-address TLVs for both passive and non-passive interfaces. IS-IS “advertise interface-address passive-only” feature is used to control the advertisement of interface address TLVs in LSP Advertisement. Once this feature is enabled on the device, IS-IS advertises interface address TLVs i,e. IP Interface Address TLV #132 and IPv6 Interface Address TLV #232 only for passive interfaces in the LSP Advertisement and stops advertising these TLVs for active or non-passive interfaces.