MRTFRR Architecture Algorithms Analysis and Extensions Alia Atlas

Outline: Discussing MRT-FRR Drafts • • • draft-ietf-rtgwg-mrt-frr-architecture-03 draft-enyedi-rtgwg-mrt-frr-algorithm-03 Analysis of MRT-FRR on Network

Architecture: Comparison +---------------+-----------------+ | Method | Coverage | Alternate | Computation (in SPFs) |

Architecture: Text Changes & Clarifications • Partial Deployment – Form MRT Island can protect

Architecture: Multi-homed Prefixes • End-point Selection (for IP) – Local Decision for alternate selection

Architecture Summary • Very stable and clarified – please read if you’ve read an

Algorithm Draft Changes • Focused on Lowpoint Algorithm – Moved hybrid and SPF versions

Algorithm Draft Next Steps • May add backwards-compatible improvement: shortcut for alternates – Idea

Evaluating IPFRR technologies on service provider network topologies • Failure coverage • MRT vs.

link and node failure coverage 100. 0% 90. 0% 80. 0% Coverage 70. 0%

Average relative alternate path for all topologies modeled 100 87 3. 00 Path length

Path length distribution for one topology 25000 MRT alternate path length 20000 node-protecting RLFA

Alternate selection priorities for this MRT analysis 1. node-protecting downstream local LFA 2. node-protecting

Overview of OSPFv 2 and OSPFv 3 Extensions • MRT Capability: – Uses a

Planned Changes: for MT Routing Adding support for multi-topology routing so primary can have

GADAG Root Selection Priority • Picking a good GADAG Root improves the length of

Goals of Extensions • Confirm MRT capability and support • Provide for supporting multiple

What is needed from LDP • New Capability – need to know that peer

Overall Summary • MRT-FRR architecture is mature • Algorithm draft is stable and ready

Slides: 24

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MRT-FRR: Architecture, Algorithms, Analysis, and Extensions Alia Atlas, Gabor Enyedi, Andras Csaszar, Bob Kebler, Shraddha Hegde, Chris Bowers, Jeff Tantsura, Abishek Gopalan, Kishore Tiruveedhula, Russ White, IJ Wijnands, Maciek Konstantynowicz, Zhenbin Li, Nan Wu, Quintin Zhao IETF 87, Berlin, Germany IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 1

Outline: Discussing MRT-FRR Drafts • • • draft-ietf-rtgwg-mrt-frr-architecture-03 draft-enyedi-rtgwg-mrt-frr-algorithm-03 Analysis of MRT-FRR on Network Topologies draft-atlas-ospf-mrt-00 draft-atlas-mpls-ldp-mrt-00 IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 2

Architecture: Text Changes & Clarifications • Partial Deployment – Form MRT Island can protect against destinations outside MRT Island • Importance of 100% coverage – Protection during maintenance changes or after a failure – Topology agnostic – freedom for IGP metric engineering and network architecture – Preventing micro-forwarding loops usually extends network convergence times, which is only harmless with 100% coverage. – Multicast node vs. link protection (via p 2 p tunnels) depends on assumption that link protection is 100% available. • Clarified final architecture decisions. IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 4

Architecture: Defined Default MRT Profile • Defining MRT Profiles for flexibility – for different applications if desired (MRT-FRR, Multicast live-live) – to change to new algorithm or behavior • MRT Profiles for simplicity – Just indicate profile and not all the details that means in signaling • MRT Profile describes required behavior for other routers IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 5

Architecture: Multi-homed Prefixes • End-point Selection (for IP) – Local Decision for alternate selection – Pick another router advertising the prefix and tunnel to it. – Only needed if failure point is also an advertising router (or a cut-node on path to it) • Named Proxy-Node – – Needs to have an LDP FEC for it. Advertise MRT-Red and MRT-Blue FECs also Can attach or detach without causing MRT recomputation Just like attaching prefixes to the SPT after it has been computed. IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 6

Architecture Summary • Very stable and clarified – please read if you’ve read an earlier version. • Multiple prototypes in progress – Need comments soon IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 7

Algorithm Draft Changes • Focused on Lowpoint Algorithm – Moved hybrid and SPF versions to Appendix • • Added section for a named proxy-node A bit of normative text Lowpoint algorithm very stable Added analysis IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 9

Algorithm Draft Next Steps • May add backwards-compatible improvement: shortcut for alternates – Idea clear and agreed correct – Needs coding and to see improvement vs. computation • Please tell about implementations – Interested in verifying interoperable correctness • Comments? Interested now in WG Adoption IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 10

Evaluating IPFRR technologies on service provider network topologies • Failure coverage • MRT vs. optimal (100%) • RLFA vs. optimal • Link and node-protection • Link-protection only • Link-protection with potential to loop when node fails • Alternate path length IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 12

link and node failure coverage 100. 0% 90. 0% 80. 0% Coverage 70. 0% 60. 0% MRT 50. 0% 40. 0% RLFA 30. 0% 20. 0% 10. 0% T 101 T 102 T 103 T 104 T 105 T 106 T 107 T 108 T 109 T 110 T 111 T 112 T 113 T 114 T 115 T 116 T 117 T 118 Topology link-only failure coverage 100. 0% MRT 90. 0% 80. 0% Coverage 70. 0% RLFA with possible loops 60. 0% 50. 0% 40. 0% RLFA without possible loops 30. 0% 20. 0% 10. 0% T 101 T 102 T 103 T 104 T 105 T 106 T 107 T 108 T 109 T 110 T 111 T 112 T 113 T 114 T 115 T 116 T 117 T 118 Topology IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 13

Average relative alternate path for all topologies modeled 100 87 3. 00 Path length relative to optimal 2. 50 2. 00 MRT 1. 50 RLFA next-hop 1. 00 0. 50 0. 00 T 101 T 102 T 103 T 104 T 105 T 106 T 107 T 108 T 109 T 110 T 111 T 112 T 113 T 114 T 115 T 116 T 117 T 118 Topology IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 14

Path length distribution for one topology 25000 MRT alternate path length 20000 node-protecting RLFA 15000 link-protecting RLFA only 10000 no RLFA (path length effectively infinite) y=x 5000 0 0 5000 10000 15000 optimal path length (node-protecting if possible) 20000 1600 14000 24000 1400 13500 23500 1200 13000 23000 12500 22500 800 12000 22000 600 11500 21500 400 11000 200 10500 20500 10000 20000 0 0 500 IETF 87 MPLS: 2 August 2013 1000 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 25000 21000 22000 15

Alternate selection priorities for this MRT analysis 1. node-protecting downstream local LFA 2. node-protecting MRT alternate 3. link-protecting downstream local LFA 4. MRT alternate Alternate selection priorities for this RLFA analysis 1. node-protecting local LFA 2. link-protecting remote LFA providing node-protection 3. link-protecting downstream local LFA 4. link-protecting downstream remote LFA 5. link-protecting local LFA IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 16

Overview of OSPFv 2 and OSPFv 3 Extensions • MRT Capability: – Uses a bit from the Router-LSA • MRT Profile supported and associated GADAG Root Selection Priority – In TLV for Router Information LSA • Flood local MRT-ineligible links for consistent topology • Flood local worst-case convergence time to derive network worst-case convergence time – Old idea from draft-atlas-bryant-shand-lf-timers Merging with draft-li-rtgwg-igp-ext-mrt-frr-01 IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 18

Planned Changes: for MT Routing Adding support for multi-topology routing so primary can have an MT-ID. • MRT Profile TLV in Router Information LSA 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Profile ID | GADAG Priority |0|Primary MT-ID| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MRT-Blue MT-ID | MRT-Red MT-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Profile ID 0: default MRT Profile If the MRT-Blue MT-ID is 0, then the value specified in the associated MRT Profile is assumed. If the MRT-Red MT-ID is 0, then the value specified in the associated MRT profile is assumed. • MRT-Ineligible Links (shown for OSPFv 2 – similar for OSPFv 3) 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link Data | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type |0|Primary MT-ID| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 19

GADAG Root Selection Priority • Picking a good GADAG Root improves the length of the alternates significantly. • Off-line analysis can identify good candidates (e. g. closeness centrality) • Default value, if unspecified, is 100 – which allows specifying priorities above or below. • Only routers that are good (or bad) GADAG Root candidates need to advertise the MRT Profile TLV in the Router Information LSA. IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 20

Goals of Extensions • Confirm MRT capability and support • Provide for supporting multiple MRT Profiles – Matches into the MRT island for Primary MT-ID, if MRT Profile and MRT-Blue MT-ID and MRT-Red MT-ID match • Ability to remove links from the topology used by MRT algorithm – Sec 3. 2. 1 of draft-ietf-rtgwg-lfa-manageability-00 requires the ability to mark a link as a non-candidate. • Worst-Case Convergence Time – Used to decide when to start computing (or installing) MRTs and alternates. – Will also be useful for micro-loop prevention techniques. IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 21

What is needed from LDP • New Capability – need to know that peer supports MRT and its use of MTFECs. • For inter-area/inter-level case, need to signal different label for same (MT-ID, IP Prefix) – Define “Rainbow MT-ID” – indicates supplied label applies to • All (Blue MT-ID, IP Prefix), • All (Red MT-ID, IP Prefix), and • (MT-ID = 0, IP Prefix) – Can also use Rainbow MT-ID as egress – Means same label always advertised for same MT-FEC, but different MT-FECs may be sent to different neighbors. IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 23

Overall Summary • MRT-FRR architecture is mature • Algorithm draft is stable and ready • Signaling extensions defined – OSPF, LDP this time – ISIS soon – Needed for interoperable implementations • Prototypes underway • Interested in feedback IETF 87 MPLS: 2 August 2013 draft-ietf-rtgwg-mrt-frr-architecture-03, etc. 24