IS-IS Spine-Leaf IETF 97, Seoul Naiming Shen, Cisco Sanjay Thyamagundalu, Cisco

Draft History draft-shen-isis-spine-leaf-ext-02 First presented at IETF 96 in Berlin Removed the ‘Default Route Metric’ field from the Spine-Leaf TLV, and changed to using Reverse Metric in IIH PDU Published 02 version in October 2016

Spine-Leaf Use Cases Spine-Leaf Setup popular in Data Center and Campus Normally leaf-to-leaf traffic goes through one of the spine nodes, for east-west Basically some ECMP load sharing from leaf to spine nodes Rich mesh of spine-leaf topology generates LSP flooding issues

TLV in Hello PDU L: Leaf mode bit; R: Default Route Gateway bit; B: Leaf-Leaf bit ‘Default Route metric’ is removed. Can use IS-IS Reverse Metric from Spine to Leaf nodes

Extension Operation (1/2) Core Layer with IS-IS Full IS-IS Database Normal ISIS Operation S1 S2 Aggregation Layer Only default routes to Spines ISIS Hello, Leaf-bit set ISIS LSP flood to Spine ISIS Hello, Use me as ‘default’ L1 L2 L3 Access Layer

Extension Operations (2/2) For point-to-point IS-IS link Spine nodes have interconnections, include the ‘Core’ layer on top of ‘Aggregation’ layer CSNP is not needed over the SL link Allow Leaf-to-leaf local exchange Leaf set ‘OL’ bit in its LSP Spine may pass ‘Hostname’ in IIH Spine may send different ‘Reverse Metric’ to influence the leaf’s ECMP

Next Steps Review and comment and discussion Request WG Adoption