introduction to segment routing
TRANSCRIPT
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 1Cisco Confidential 1© 2013 Cisco and/or its affiliates. All rights reserved.
Ismail AliTechnical Consultant, Cisco Systems Malaysia
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 2
• Introduction
• Incremental Deployment Use Cases
• Standardization
• Conclusion
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 3
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 4
• Source Routing: source chooses a path and encodes it in packet header as an ordered list of segments.
• Segment: an identifier for any type of instructionServiceContextLocatorIGP-based forwarding constructBGP-based forwarding constructLocal value or Global Index
Segment = Instructions such as "go to node N using the shortest path"
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 5
• MPLS: an ordered list of segments is represented as a stack of labelsSR re-uses MPLS data plane without any change
• IPv6: an ordered list of segments is represented as a routing extension header
This presentation focuses on MPLS data plane
IPv6 IPv6
IPv6
Control Plane
IPv4
MPLSData Plane
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 6
• Locally significant to node allocating it
• Node processes SID and switches packet towards adjacency
• Advertised as an absolute value
• Globally significant within SR domain
• All nodes switch packet towards prefix/node via shortest path
• Advertised as a relative (index) value
• Make use of a per-node reserved block (SR Global Block or SRGB)
B C
N O
Z
D
P
A
91019105
9107
9103
9105
B C
N O
Z
D
P
A
65
65
65 65
Prefix/Node SID Adjacency SID
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 7
D(php)
7
A B
C D
E103
103
Payload Payload
201202
Payload
202201202
Payload
202
Payload Payload
C D
A B
E
202
202
201
102202
Payload
A B102
C D
E
202
Payload
202Payload
C E C D EB C D(php)
EB
Node Path Adjacency Path Combined Path
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 8
• Efficient packet networks leverage ecmp-aware shortest-path!node segment!
• Simplicityone less protocol to operateNo complex LDP/ISIS synchronization to troubleshoot
8
A B
M N
PE2PE1
All VPN services ride on the node segment to PE2
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 9
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 10
• Tokyo to Brusselsdata: via US: cheap capacityVoIP: via Russia: low latency
• CoS-based TE with SRIGP metric set such asTokyo to Russia: via Russia
Tokyo to Brussels: via US
Russia to Brussels: via Europe
Anycast segment “Russia” advertised by Russia core routers
• Tokyo CoS-based policyData and Brussels: push the node segment to Brussels
VoIP and Brussels: push the anycast node to Russia, push Brussels
10
Node segment to Brussels
Node segment to Russia
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 11
• For Traffic Engineering
• or for OAM
11
B C
N O
Z
D
P
A
91019105
9107
9103
9105
91019101
91059107
91039105
9101
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 1212
Path ABCOPZ is ok. I account the BW. Then I steer the traffic on this path
FULL66
6568
Tunnel AZ onto {66, 68, 65}
The network is simple, highly programmable and responsive to rapid changes
2G from A to Z please
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 13
Definition
Applications express requirements –bandwidth, latency, SLAs
SDN controllers are capable of collecting data from the network – topology, link states, link utilization, …
Applications are mapped to a path defined by a list of segments
The network only maintains segmentsNo application state
Segment Routing
SDNController
Applications1
2
3
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 14
• Applications program the network on a per-flow basis
• End-to-End policyDC, WAN, AGG, PEER
• Millions of flowsNo per-flow midpoint stateNo reclassification atboundaries
• SimpleBGP and ISIS/OSPF
DC (or AGG)
10
11
12
13
14
2 4
6 5
7
Default ISIS cost metric: 10Default Latency metric: 10
50
WAN
3
1
PEER
Low Lat, Low BW
High-BW to 7for application …
Push{16001,
16005}
High Lat, High BW
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 15
• Automated 50msec FRR
DC (or AGG)
10
11
12
13
14
2 4
6 5
7
Default ISIS cost metric: 10Default Latency metric: 10
50
WAN
3
1
PEER
Low Lat, Low BW
High-BW to 7for application …
Push{16001,
16005}
High Lat, High BW
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 16
• Any policy can be programmed by the application
• The network scaling and simplicity is preserved
DC (or AGG)
10
11
12
13
14
2 4
6 5
7
Default ISIS cost metric: 10Default Latency metric: 10
50
WAN
8
8
PEER
Low Lat, Low BW
High-BW to 7Load-share across DC edgesfor application …
Push{16008,
16005}
High Lat, High BW
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 17
• Any policy can be programmed by the application
• The network scaling and simplicity is preserved
DC (or AGG)
10
11
12
13
14
2 4
6 5
7
Default ISIS cost metric: 10Default Latency metric: 10
50
WAN
3
1
PEER
Low Lat, Low BW
Low-Latency to 7, DC Plane 0 onlyfor application …
Push{16010,
16001,200, 147}
High Lat, High BW
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 18
• Any policy can be programmed by the application
• The network scaling and simplicity is preserved
DC (or AGG)
10
11
12
13
14
2 4
6 5
7
Default ISIS cost metric: 10Default Latency metric: 10
50
WAN
3
1
PEER
Low Lat, Low BW
High-BW to 7,1st VNF at 142nd VNF at 6 for application …
Push{16014,
301,16003,16006,302, 16005}
High Lat, High BW
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 19
Adding value at your own pace
Enable Segment Routing on the network (Software only)
Insert Orchestration, SDN controller
Connect with Cisco’s and third party VNFs
Network Simplification
Network Resiliency
End-User Experience
Network Optimization
Service Velocity
E2E Application Control
Benefits
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 20Cisco Confidential 20© 2013 Cisco and/or its affiliates. All rights reserved.
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 21
• Control plane scale and complexity• Many protocols• Many encapsulations• Many bugs• Forwarding plane capacity• Lots of growth == lots of stress
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 22
• Peering --- want programmatic control over policy• Massively Scaled Datacenters (even more protocols, high device and link counts, commodity hardware, greater vendor diversity, legacy applications)• Inter-DC vs External workloadsLatency-sensitive vs bulkScheduled vs unscheduled
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 23
• Reduced complexityProtocol counts
Fewer protocols == less code == fewer bugsAmount of distributed control plane stateUnified forwarding plane (analog of BGP is the Better IGP )
• Maintain healthy vendor diversity• Want to (eventually and incrementally) enable software control
Leverage our in-house software (and networking) expertiseRe-use ongoing controller and TE work
Don’t want another new parallel network
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 24
• Well-understood forwarding plane (MPLS)• Encourages sensible engineering tradeoffs• Possibility of removing some distributed signaling protocols• Removes per-tunnel state from the core• Gets us closer to a static core, significantly quieter control plane• Good interop with existing protocols
Safe incremental deployment
• SDN with standards-based interfacesSegments are defined at a useful level of abstraction for compositionAnycast is also useful
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 25
• Autopilot for orchestration • SWAN for TE• BGP-LS for topology and SR label discovery• BGP-LU for creating tunnels
Widely supported, so we can impose on the non-SR edgeSingle label (but can hack w/Route Resolution)
Label stacks would be nicerCan scale with indirection and vanilla BGPNon-standard use of RFC 3107, maybe we can do better
• BGP prefix SID’s for the MSDC• EPE scenario for peering
BMP for route collection
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 26
• Built out a full emulation of core network using VM’s running early vendor(s) codeFantastic tool, please more fidelity.
• Modeled the entire control plane w/MPLS forwardingObviously slower in the forwarding plane
• Very basic controller driving BGP-LU via REST
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 27
• Investigated several use cases:Basic forwarding over an SR routed networkTraffic steeringEPEVendor interopServer-to-server
• Found a few bugs and interop issuesMostly design/use cases.
• Management is on the thin sideStill awkward to see some SR stateNot quite fully integrated
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 28
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 29
• IETF standardization in SPRING working group
• Protocol extensions progressing in multiple groupsIS-ISOSPFPCEIDR6MAN
• Broad vendor and customer support
Sample IETF DocumentsSegment Routing Architecture
(draft-ietf-spring-segment-routing)
Problem Statement and Requirements(draft-ietf-spring-problem-statement)
IPv6 SPRING Use Cases (draft-ietf-spring-ipv6-use-cases)
Segment Routing Use Cases (draft-filsfils-spring-segment-routing-use-cases)
Topology Independent Fast Reroute using Segment Routing(draft-francois-spring-segment-routing-ti-lfa)
IS-IS Extensions for Segment Routing(draft-ietf-isis-segment-routing-extensions)
OSPF Extensions for Segment Routing(draft-ietf-ospf-segment-routing-extensions)
PCEP Extensions for Segment Routing(draft-ietf-pce-segment-routing)
Close to 30 IETF drafts in progress
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 30
• Strong commitment for standardization andmulti-vendor support
• SPRING Working-Group• All key documents are WG-status• Over 25 drafts maintained by SR teamOver 50% are WG statusOver 75% have a Cisco implementation
• Several interop reports are available
www.segment-routing.nettools.ietf.org/wg/spring/
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 31
• Fundamental to the velocity and success• Over 30 operators involved• Technology tailored to solve real requirementsTactical: solve long-reported issuesStrategic: key architecture for long-term evolution
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 32
• Platforms: ASR9000, CRS-1/CRS-3, WAE (shipping)
• IS-IS IPv4 (shipping)Node/Adjacency SID advertisementLDP interworking (mapping server/client)Traffic protection (topology independent LFA link protection)
• OSPFv2 (shipping)Node SID advertisementTraffic protection (LFA)
• UpcomingIS-IS / OSPFv2 paritySR Traffic Engineering (manual provisioning and PCEP)OAM (Ping/Trace)
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 33
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 34
• Simple routing extensions to implement source routing
• Packet path determined by prepended segment identifiers (one or more)
• Data plane agnostic (MPLS, IPv6)
• Network scalability and agility by reducing network state and simplifying control plane
• Traffic protection with 100% coverage with more optimal routing
• Interworking capabilities with LDP-only devices
34
© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 35
Thank you.
http://tools.ietf.org/wg/spring/http://www.segment-routing.net/