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

2. 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

3. 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

4. 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

5. 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

6. 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

7. Next Steps
Review and comment and discussion
Request WG Adoption