IGP Multicast Architecture Lucy Yong, Weiguo Hao, Donald Eastlake Andrew Qu, Jon Hudson, Uma Chunduri February 2015 NVO3 Interim Meeting draft-yong-rtgwg-igp-mutlicast-arch-01

Motivation Trend is to decouple network IP space from service IP space in Data Center environment – Benefits: networking agility and programmability to applications that are in IP and non-IP space – Service IP space is known as overlay net., network IP as underlay net. If network IP space is decoupled from service IP space, – Underlay IP network itself no longer needs manual configuration – Automatic formation of an IP network fabric can be done (i.e. underlay IP) – IP network fabric can be simplified by reducing protocols IP network fabric needs support unicast and multicast transport – IGP protocol already supports unicast – IGP protocol does not yet support multicast, simple extension will do 2February 2015NVO3 Interim Meeting

IGP Multicast Architecture Support IP multicast packets delivery in an IGP network Use single IGP protocol for unicast and multicast packets delivery No change on the IGP protocol for unicast packet routing and forwarding Use of existing hardware, i.e., data plane Require simple IGP protocol extension for IP multicast packet delivery 3February 2015NVO3 Interim Meeting

IGP Multicast Architecture A set of edge routers and transit routers: – They are IGP routers and support IGP multicast – Multicast source(s) and receiver(s) connect to at least one edge router – IGP multicast supports multi-tenant environment (IP or non-IP) tenants can use the same multicast address space independently 4February 2015NVO3 Interim Meeting R1 R2 R3 R4 R5 R6 R7 R8 R9 R1-R6 are edge routers R7-R9 are transit routers Example: A IGP Network with Multicast Capability

IP Multicast Packet Delivery over a Tree An algorithm selects a default tree root node or operator can configure the tree root(s) Routers in IGP compute rooted distrib. tree(s) based on LSDB Each multicast group associates to at least one distribution tree A pruned tree is done based on edge router membership on a multicast group (optimal transport) 5 R1 R2 R3 R4 R5 R6 R7 R8 R9 R1 R2 R3 R4 R5 R6 R7 R8 R9 R7 Rooted Distribution Tree (Green) Pruned tree for (*,G) w/[R1,R4,R6] (Green) February 2015NVO3 Interim Meeting

Tenant (overlay) multicast packets can be L3 or L2 (BUM) packets Tenant multicast packets are encap. at ingress NVE prior to forwarding over IGP Multicast Network The mapping b/w tenant multicast family and a underlay (*,G) can be configured or done by the policy at NVEs NVE and IGP Edge Router may be co-located or separated Tenant multicast receivers send and/or reply an IGMP/MLD for joining/leaving a multicast family to local NVE Tenant Multicast Packet Delivery 6February 2015NVO3 Interim Meeting NVE Server Edge Router IGP Multicast Network NVE Server Edge Router IGP Multicast Network

Summary NVO3 is a primary use case for IGP Multicast IGP Mcast development will be in MCAST WG – IGP Multicast Architecture Support single area and multiple areas Support IS-IS and OSPF networks Support both IPv4 and IPv6 networks – IGP Multicast Solution (Algorithms and Process Procedures) – IS-IS and OSPF extensions for IGP Multicast 7February 2015NVO3 Interim Meeting