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Introducing Application Engineered Routing Powered by Segment Routing
Clarence Filsfils Cisco Fellow cf@cisco.com
Deployment use-cases
2 © 2014 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
Velocity • SR concept was proposed to operators in November 2012
• Only two years have elapsed since the first public SR presentation and demo – Here, March 2013
• A lot happened, let’s see!
3 © 2014 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
Deployment • In CY2015, SR will be deployed in all of these markets
WEB
SP Core/Edge
SP Agg/Metro
Large Entreprise
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“Comcast’s Converged Network is the strategic platform for delivering our Internet, Video, Voice, and Business products. As new advanced services are developed leveraging technologies like; Cloud and NFV, our network needs to simplify, scale and become extensible. We see IPv6 and Segment Routing as major elements in the evolution of the network. The ability of the network to support, not impede the innovation occurring in software and services, will be a major step forward.”
John Leddy, VP of Network Strategy, Comcast
5 © 2014 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
Strong Operator Partnership and Demand • Fundamental to the velocity and success • Over 30 operators involved
• Technology tailored to solve real requirements – Tactical: solve long-reported issues – Strategic: key architecture for long-term evolution
6 © 2014 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
IETF • Strong commitment for standardization and
multi-vendor support
• SPRING Working-Group
• All key documents are WG-status • Over 25 drafts maintained by SR team
– Over 50% are WG status – Over 75% have a Cisco implementation
• Several interop reports are available
www.segment-routing.net tools.ietf.org/wg/spring/
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Segment Routing • Source Routing – the source chooses a path and encodes it in the packet header as an
ordered list of segments – the rest of the network executes the encoded instructions without any
further per-flow state
• Segment: an identifier for any type of instruction – forwarding or service
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IGP Prefix Segment
• Shortest-path to the IGP prefix
• Global
• 16000 + Index
• Signaled by ISIS/OSPF
DC (BGP-SR)
10
11
12
13
14
2 4
6 5
7
WAN (IGP-SR)
3
1
PEER
16005
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IGP Adjacency Segment
• Forward on the IGP adjacency
• Local
• 1XY – X is the “from”
– Y is the “to”
• Signaled by ISIS/OSPF
DC (BGP-SR)
10
11
12
13
14
2 4
6 5
7
WAN (IGP-SR)
3
1
PEER
124
10 © 2014 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
BGP Prefix Segment
• Shortest-path to the BGP prefix
• Global
• 16000 + Index
• Signaled by BGP
DC (BGP-SR)
10
11
12
13
14
2 4
6 5
7
WAN (IGP-SR)
3
1
PEER
16001
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BGP Peering Segment
• Forward to the BGP peer
• Local
• 1XY – X is the “from”
– Y is the “to”
• Signaled by BGP-LS (topology information) to the controller
DC (BGP-SR)
10
11
12
13
14
2
6
7
WAN (IGP-SR)
3
1
PEER
Low Lat, Low BW 4
5 High Lat, High BW
147
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WAN Automation Engine
• WAE collects via BGP-LS – IGP segments
– BGP segments – Topology
DC (BGP-SR)
10
11
12
13
14
2 4
6 5
7
WAN (IGP-SR)
3
1
PEER
Low Lat, Low BW
BGP-LS
BGP-LS
BGP-LS
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An end-to-end path as a list of segments
• WAE computes that the green path can be encoded as – 16001
– 16002
– 124 – 147
• WAE programs a single per-flow state to create an application-engineered end-to-end policy DC (BGP-SR)
10
11
12
13
14
2 4
6 5
7
WAN (IGP-SR)
3
1
PEER
Low Lat, Low BW
50
Default ISIS cost metric: 10
{16001, 16002, 124, 147}
PCEP, Netconf, BGP
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PCEP-reply (OK, BSID: 200)
Binding Segment • WAE instructs edge to install an SRTE policy
– For this traffic, push this list of segments
• WAE defines the SRTE policy – Explicit: it provides an explicit list of segments – Dynamic: it provides optimization objective and constraints to
the edge router. The edge router computes the list of segments to match these objectives.
• The edge router assigns a binding segment to the SRTE policy and installs it in dataplane – Pop and Push the related list of segments – Binding segment is local
• Controller collects binding segments and characteristics of the SRTE policies (e.g. PCEP)
2 4
6 5
Default ISIS cost metric: 10 Default Latency metric: 10
WAN
3
1
PCEP-request (SR Policy, low-latency, to 4)
200: pop and push {16002, 124}
50
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An end-to-end path with binding segment
• WAE computes that the green path can be encoded as – 16001
– 200
– 147
• WAE programs a single per-flow state to create an application-engineered end-to-end policy
DC (or AGG)
10
11
12
13
14
2 4
6 5
7
Default ISIS cost metric: 10 Default Latency metric: 10
50
WAN
3
1
PEER
Low Lat, Low BW
Low-Latency to 7 for application …
Push {16001, 200, 147}
16 © 2014 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
Application Engineered Routing 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 segments No application state
Segment Routing
(SW upgrade)
SDN Controller
Applications 1
2
3
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Application Engineered Routing
• Applications program the network on a per-flow basis
• End-to-End policy – DC, WAN, AGG, PEER
• Millions of flows – No per-flow midpoint state
– No reclassification at boundaries
• Simple – BGP and ISIS/OSPF
DC (or AGG)
10
11
12
13
14
2 4
6 5
7
Default ISIS cost metric: 10 Default Latency metric: 10
50
WAN
3
1
PEER
Low Lat, Low BW
High-BW to 7 for application …
Push {16001, 16005}
High Lat, High BW
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Application Engineered Routing
• Automated 50msec FRR
DC (or AGG)
10
11
12
13
14
2 4
6 5
7
Default ISIS cost metric: 10 Default Latency metric: 10
50
WAN
3
1
PEER
Low Lat, Low BW
High-BW to 7 for application …
Push {16001, 16005}
High Lat, High BW
19 © 2014 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
Application Engineered Routing
• 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: 10 Default Latency metric: 10
50
WAN
8
8
PEER
Low Lat, Low BW
High-BW to 7 Load-share across DCedges for application …
Push {16008, 16005}
High Lat, High BW
20 © 2014 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
Application Engineered Routing
• 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: 10 Default Latency metric: 10
50
WAN
3
1
PEER
Low Lat, Low BW
Low-Latency to 7, DC Plane 0 only for application …
Push {16010, 16001, 200, 147}
High Lat, High BW
21 © 2014 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
Application Engineered Routing
• 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: 10 Default Latency metric: 10
50
WAN
3
1
PEER
Low Lat, Low BW
High-BW to 7, 1st VNF at 14 2nd VNF at 6 for application …
Push {16014, 301, 16003, 16006, 302, 16005}
High Lat, High BW
22 © 2014 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
Application Engineered Routing Journey 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
Incremental Deployment Use-Cases
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Demonstrating these use-cases • This section illustrates various use-cases that can be deployed incrementally
• Kris Michielsen and Roberta Maglione are available at the Cisco booth to demonstrate these use-cases
• Also leverage dcloud.cisco.com where you can test these use-cases by yourself
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Planning your Deployments • Mate Design – TILFA FRR – Centralized BW Optimization – Traffic Engineering > Latency vs Cost > Exclusion/Inclusion ip address, srlg, affinity > Disjointness
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IPv4 VPN/Service transport • IGP only – No LDP, no RSVP-TE
• ECMP 1
2 3
4
6 5
7
Site1 Site2
pkt
16007 vpn
pkt
16007 vpn
pkt
pkt vpn
pkt
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IPv6 VPN/Service transport over v4 segments • IGP only – No LDP, no RSVP-TE
• ECMP
1
2 3
4
6 5
7
Site1 Site2
pkt
16007 6PE
pkt
16007 6PE
pkt
pkt 6PE
pkt
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IPv6 Internet transport over v6 segments • IGP only – No LDP, no RSVP-TE
• ECMP 1
2 3
4
6 5
7
V6 Internet V6 Internet
pkt 16007
pkt 16007
pkt
pkt
pkt
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Seamless interworking with LDP • Seamless deployment
1
2 3
4
6 5
7
Site1 Site2
pkt
pkt vpn
pkt
pkt
16007 vpn
pkt
16007 vpn
pkt vpn
LDP(7)
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FRR Classic (ATM-alike) • Midpoint backup circuit states • Non-Optimum
– Back to next-hop and then forward
• Extra Signalling Protocol over IGP – RSVP-TE
• Not ECMP
1
2 3
4
6 5
7
pkt 16007
circuit
pkt 16007
pkt 16007
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TILFA FRR • 50msec FRR in any topology
• IGP Automated – No LDP, no RSVP-TE
• Optimum – Post-convergence path
• No midpoint backup state
• Detailed operator report – S. Litkowski, B. Decraene, Orange
• Mate Design – How many backup segments
– Capacity analysis
1
2 3
4
6 5
7
pkt 16007 16005
pkt 16007
pkt 16007
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OAM • A centralized application can engineer its OAM probes along any selected path
• Correlation between different probes allows to localize problems
draft-geib-spring-oam-usecase-02
1
2 3
5 4
pkt
154
135
123
112
125
132
143
151
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Large-Scale Aggregation
• Only IGP/SR (no BGP) – Automated FRR including ASBR failure
• SRGB (k) << # access nodes (100k)
• SDN Controller programs the segment list together with service creation
Core Acces1 Acces2 A 70
B 72
ASBR2A 1002
ASBR2B 1002
C 72
ASBR SID’s are anycast ASBR SID’s are unique across the entire domain ASBR anycast prefixes and SID are redistributed within each access region Access Nodes are provided a SID which is unique with respect to its attached ASBR’s but not necessarily unique across the whole domain
{72} leads to B within Access1 {72} leads to C within Access2 {1001, 72} leads to B from anywhere {1002, 72} leads to C from anywhere
ASBR1A 1001
ASBR1B 1001
Evolve Carrier Ethernet Architecture with SDN and Segment Routing
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Traffic Engineering with SR • No midpoint state (n^2 scale In RSVP-TE)
• No extra protocol (RSVP-TE)
• Native ECMP
• Few segments are required – Apply Mate Design on your data
• Distributed computation or Centralized – Optimize on Cost, Latency or BW – Include/exclude Address, Affinity, SRLG – Disjointness
• Integration with IP/Optical optimization
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Latency example • Dynamic path-option computed by the head-end
1
2
4
6 5
7
Default ISIS (cost) metric: 10 Default latency metric: 10
ISIS: 50
pkt 16007
Low Cost to 7
pkt
16002 124
16007 Low Latency to 7
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0 20 40 60 80 100
ICDF (%)
0
10
20
30
40
50
60
70
Over
hea
dco
mp
are
dto
min
imal
del
ay
path
(ms)
IGP path
1 segment
2 segments
Latency path
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Avoidance example • Dynamic path-option computed by centralized PCE
1
2
4
6 5
7
pkt 16007
Low Cost to 7
pkt
16005 16007
Low Cost to 7 & avoid blue
PCEP request
PCEP reply
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Centralized Traffic Engineering
0 20 40 60 80 100 120
050
100
150
X1 [links] − SR TE Results (failures)
Failure #
Max
. Util
izat
ion
(%)
●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●
●●●●●●●●●●●●●●●●●●●
●●●●●●●●●●●
●●●●●●●●●●●●●●●●●●●●●●●
●●●●●●●●●●●●●●●●
●●●●●●●●●●●●
●
IGP utilSRTE util# SRTE tunnels
0 50 100 150
050
100
150
200
250
X1 [srlgs] − SR TE Results (failures)
Failure #
Max
. Util
izat
ion
(%)
●
●●●●●●●●●●
●
●●●●●
●
●●●●●
●
●●●●●●●●●●●●●●●
●
●●●●●●●●●●●●●●●
●
●●●●●●●●●●●
●
●●●●●●●
●
●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●
●
●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●
●
IGP utilSRTE util# SRTE tunnels
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Classic Content Delivery • Default content from 4 to 7
– Via shortest IGP path to best BGP nhop
• Alternate connectivity is not leveraged although potentially offering – lower congestion / latency – better business policies
1 2
6
4 3 AS1
5
7
AS6 AS5
AS7
pkt 16001
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Optimized Content Delivery • On a per-content, per-user basis, the content delivery application can engineer – the path within the AS – the selected border router – the selected peer
• Also applicable for engineering egress traffic from DC to peer – BGP Prefix and Peering Segments
1 2
6
4 3 AS1
5
7
AS6 AS5
AS7
pkt
16003 16002
126
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Binding Segment • Any router who is the headend
of an SRTE policy installs in dataplane a binding segment
• A binding segment is local • Dataplane behavior
– Pop and push the list of segments associated with the SRTE policy
• Controller collects binding segments and characteristics of the SRTE policies (e.g. PCEP)
2 4
6 5
Default ISIS cost metric: 10 Default Latency metric: 10
ISIS: 35
WAN
3
1
PCEP-request (SR Policy, low-latency, to 4)
200: pop and push {16002, 16004}
PCEP-reply (OK, BSID: 200)
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Application Engineered Routing
• Per-application flow engineering
• End-to-End – DC, WAN, AGG, PEER
• Millions of flows – No signaling – No midpoint state
– No reclassification at boundaries
DC (or AGG)
10
11
12
13
14
Push {16001, 200, 147}
Low-Latency to 7 for application A12
2 4
6 5
7
Default ISIS cost metric: 10 Default Latency metric: 10
ISIS: 35
WAN
3
1
BSID: 200
200: pop and push {16002, 16004}
PEER
Low Lat, Low BW
Low-Lat to 4
PeerSID: 147, Low Lat, Low BW
PeerSID: 147, High Lat, High BW
43 © 2014 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
Application Engineered Routing
• Per-application flow engineering
• End-to-End – DC, WAN, AGG, PEER
• Millions of flows – No signaling – No midpoint state
– No reclassification at boundaries
DC (or AGG)
10
11
12
13
14
Push {16010, 16001, 200, 147}
Low-Latency to 7, DC Plane 0 only, for application A12
2 4
6 5
7
Default ISIS cost metric: 10 Default Latency metric: 10
ISIS: 35
WAN
3
1
BSID: 200
200: pop and push {16002, 16004}
PEER
Low Lat, Low BW
Low-Lat to 4
PeerSID: 147, Low Lat, Low BW
PeerSID: 147, High Lat, High BW
Conclusion
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Application-Engineered Routing • Application programs the Segment Routing network to deliver
end-to-end per-flow policy from DC through WAN to end-user
• Adding value at your own pace – Leveraging the existing MPLS dataplane without any change. SW upgrade only.
– Simplification, Automated 50msec FRR, per-domain and then end-to-end policies
• Economic gains – Improved service richness and velocity – Optimized CAPEX and OPEX thanks to the simplicity of the SR architecture
• Segment Routing deployments in CY15 in all the markets – WEB, SP, Entreprise
• Strong partnership with lead operator group
• Commitment to standardization and multi-vendor support
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• http://www.segment-routing.net/ • ask-segment-routing@cisco.com
Stay Informed
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Thank you
Appendix
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The circuit alternative
• Maintaining per-flow circuit state at each hop,
with complex reclassification at domain boundaries, does not support the application needs for end-to-end programmed policy at scale
DC (or AGG)
10
11
12
13
14
2 4
6 5
7
Default ISIS cost metric: 10 Default Latency metric: 10
ISIS: 35
WAN
3
1
PEER
Low Lat, Low BW
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Circuit State WAE
WAE
WAE Orch
Classif State
Per-Flow SR State
Per-Flow SR State {16001,
124
NSO
Classif. State
APP
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