Introduction to Segment Routing
Michael Kowal, Vertical Solutions Architect@ciscomk
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public 3BRKRST-2124
Abstract
This session provides an overview of the segment routing technology and its use cases. This new routing paradigm provides high operational simplicity and maximum network scalability and flexibility. You will get an understanding of the basic concepts behind the technology and its wide applicability ranging from simple transport for MPLS services, disjoint routing, traffic engineering and its
benefits in the context of software defined networking. Previous knowledge of IP routing and MPLS is required.
Introduction to Segment Routing
• Technology Overview
• Use Cases
• A Closer Look at the Control and Data Planes
• Traffic Protection
• Traffic Engineering
• Conclusion
Agenda
Technology Overview
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
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
• Segment: an identifier for any type of instruction– forwarding or service
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© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Segment Routing – Forwarding Plane
• MPLS: an ordered list of segments is represented as a stack of labels
• IPv6: an ordered list of segments is encoded in a routing extension header
• This presentation: MPLS data plane
BRKRST-2124 7
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
IGP Prefix Segment
• Shortest-path to the IGP prefix
• Global
• 16000 + Index
• Signaled by ISIS/OSPF
8
DC (BGP-SR)
10
11
12
13
14
2 4
6 5
7
WAN (IGP-SR)
3
1
PEER
16005
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
IGP Adjacency Segment
• Forward on the IGP adjacency
• Local
• 1XY• X is the “from”
• Y is the “to”
• Signaled by ISIS/OSPF
9
DC (BGP-SR)
10
11
12
13
14
2 4
6 5
7
WAN (IGP-SR)
3
1
PEER
124
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
BGP Prefix Segment
• Shortest-path to the BGP prefix
• Global
• 16000 + Index
• Signaled by BGP
10
DC (BGP-SR)
10
11
12
13
14
2 4
6 5
7
WAN (IGP-SR)
3
1
PEER
16001
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
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
11
DC (BGP-SR)
10
11
12
13
14
2
6
7
WAN (IGP-SR)
3
1
PEER
Low Lat, Low BW
4
5High Lat, High BW
147
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
WAN Controller
• SR PCE collects via BGP-LS• IGP segments
• BGP segments
• Topology
12
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
BRKRST-2124
SR
PCE
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
An end-to-end path as a list of segments
• SR PCE computes that the green path can be encoded as• 16001
• 16002
• 124
• 147
• SR PCE programs a single per-flow state to create an application-engineered end-to-end policy
13
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
BRKRST-2124
SR
PCE
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Segment Routing Standardization
• IETF standardization in SPRING working group
• Protocol extensions progressing in multiple groups
• IS-IS
• OSPF
• PCE
• IDR
• 6MAN
• Broad vendor and customer support
14
Sample IETF Documents
Problem Statement and Requirements
(RFC 7855)
Segment Routing Architecture
(draft-ietf-spring-segment-routing)
IPv6 SPRING Use Cases
(draft-ietf-spring-ipv6-use-cases)
Segment Routing with MPLS data plane
(draft-ietf-spring-segment-routing-mpls)
Topology Independent Fast Reroute using Segment Routing
(draft-francois-rtgwg-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 40 IETF drafts in progress
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Segment Routing Product Support
• Platforms:
• IOS-XR (ASR9000, CRS-1/CRS-3)
• IOS-XE (ASR1000, CSR1000v, ASR902, ASR903, ISR4400)
• NX-OS (N3K, N9K)
• WAN Automation Engine (WAE)• SR Traffic Engineering
• Integration with NSO
• Upcoming
• NCS5000, NCS6000
15BRKRST-2124
Use Cases
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
IPv4/6 VPN/Service transport
• IGP only• No LDP, no RSVP-TE
• ECMP
17
1
2 3
4
6 5
7
Site1 Site2
pkt
16007
vpn
pkt
16007
vpn
pkt
pkt
vpn
pkt
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Simplest migration: LDP to SR
• Initial state: All nodes run LDP, not SR
18BRKRST-2124
1 LDP
3 4
2
5 6
LDP Domain
LDP LDP
LDP LDP
LDP LDP
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Simplest migration: LDP to SR
• Initial state: All nodes run LDP, not SR
• Step1: All nodes are upgraded to SR• In no particular order
• Default label imposition preference = LDP
19BRKRST-2124
1 LDP
3 4
2
5 6
SR+LDP Domain
SR+LDP SR+LDP
SR+LDP SR+LDP
SR+LDP SR+LDP
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Simplest migration: LDP to SR
• Initial state: All nodes run LDP, not SR
• Step1: All nodes are upgraded to SR• In no particular order
• leave default LDP label imposition preference
• Step2: All PEs are configured to prefer SR label imposition• In no particular order
20BRKRST-2124
SR+LDP Domain
1 SR
3 4
2
5 6
SR+LDP SR+LDP
SR+LDP SR+LDP
SR+LDP
segment-routing mpls sr-prefer
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Simplest migration LDP to SR
• Initial state: All nodes run LDP, not SR
• Step1: All nodes are upgraded to SR• In no particular order
• leave default LDP label imposition preference
• Step2: All PEs are configured to prefer SR label imposition• In no particular order
• Step3: LDP is removed from the nodes in the network• In no particular order
• Final state: All nodes run SR, not LDP
21BRKRST-2124
SR Domain
1 SR
3 4
2
5 6
SR SR
SR SR
SR SR
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Seamless Interworking with LDP
• Seamless Deployment
22
1
2 3
4
6 5
7
Site1 Site2
pkt
pkt
vpn
pkt
pkt
16007
vpn
pkt
16007
vpn
pkt
vpn
LDP(7)
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Topology-Independent LFA (TI-LFA 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
23
1
2 3
4
6 5
7
pkt
16007
16005
pkt
16007
pkt
16007
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Automated Traffic Matrix Collection
• Traffic Matrix is fundamental for• capacity planning
• centralized traffic engineering
• IP/Optical optimization
• Most operators do not have an accurate traffic matrix
• With SR, the traffic matrix collection is automated
24
1 2 3 4
1
2
3
4
1
2
4
3
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
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
25
1 2
6
4 3
AS1
5
7
AS6AS5
AS7
pkt
16003
16002
126
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Application Engineered Routing
• Per-application flow engineering
• End-to-End• DC, WAN, AGG, PEER
• Millions of flows• No signaling
• No midpoint state
• No reclassification atboundaries
26
DC (or AGG)
10
11
12
13
14
Push{16001,
200, 147}
Low-Latency to 7for application A12
2 4
6 5
7
Default ISIS cost metric: 10Default 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
BRKRST-2124
SR
PCENSO
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Application Engineered Routing
• Per-application flow engineering
• End-to-End• DC, WAN, AGG, PEER
• Millions of flows• No signaling
• No midpoint state
• No reclassification atboundaries
27
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: 10Default 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
BRKRST-2124
SR
PCENSO
A Closer Look at the Control and Data Planes
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public 29
MPLS Control and Forwarding Operation with Segment Routing
PE1 PE2
IGPPE1 PE2
Services
IPv4 IPv6IPv4
VPN
IPv6
VPNVPWS VPLS
Packet
TransportLDP
MPLS Forwarding
RSVP BGP Static IS-IS OSPF
No changes to
control or
forwarding plane
IGP label
distribution for
IPv4 and IPv6.
Forwarding plane
remains the same
MP-BGP
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
SID Encoding
• Prefix SID
• SID encoded as an index
• Index represents an offset from SRGB base
• Index globally unique
• SRGB may vary across LSRs
• SRGB (base and range) advertised with router capabilities
• Adjacency SID
• SID encoded as absolute (i.e. not indexed) value
• Locally significant
• Automatically allocated for each adjacency
30BRKRST-2124
SRGB = [ 16000 - 23999 ]. Advertised as base = 16,000, range = 7,999
Prefix SID = 16041. Advertised as Prefix SID Index = 41
Adjacency SID = 24000. Advertised as Adjacency SID = 24000
SR-enabled Node
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
SR IS-IS Control Plane Overview
• IPv4 and IPv6 control plane
• Level 1, level 2 and multi-level routing
• Prefix Segment ID (Prefix-SID) for host prefixes on loopback interfaces
• Adjacency SIDs for adjacencies
• Prefix-to-SID mapping advertisements (mapping server)
• MPLS penultimate hop popping (PHP) and explicit-null label signaling
31BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
router isis DEFAULTnet 49.0001.1720.1625.5001.00address-family ipv4 unicastmetric-style widesegment-routing mpls
!interface Loopback0passiveaddress-family ipv4 unicast!
!interface GigabitEthernet0/0/0/0point-to-pointaddress-family ipv4 unicast!
!!
32BRKRST-2124
Configuring Segment Routing for IPv4 Using IS-IS (Cisco IOS-XR)
Enable Segment Routing for IPv4 with
MPLS data plane
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
SR OSPF Control Plane Overview
• OSPFv2 control plane
• Multi-area
• IPv4 Prefix Segment ID (Prefix-SID) for host prefixes on loopback interfaces
• Adjacency SIDs for adjacencies
• MPLS penultimate hop popping (PHP) and explicit-null label signaling
33BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
router ospf DEFAULTrouter-id 172.16.255.1segment-routing mplssegment-routing forwarding mplsarea 0interface Loopback0passive
!interface GigabitEthernet0/0/0/0network point-to-point
!!!
34
Configuring Segment Routing for IPv4 Using OSPF (Cisco IOS-XR)
Enable Segment Routing with MPLS
data plane
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public 35
MPLS Data Plane Operation
• Packet forwarded along IGP shortest path (ECMP)
• Swap operation performed on input label
• Same top label if same/similar SRGB
• PHP if signaled by egress LSR
Payload
SRGB [16,000 – 23,999 ]
X
Payload
Swap
X
Payload
SRGB [16,000 – 23,999 ]
Y
Payload
Pop
Y
Adjacency
SID = X
X
Prefix SID Adjacency SID
Packet forwarded along IGP adjacency
Pop operation performed on input label
Top labels will likely differ
Penultimate hop always pops last adjacency SID
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Payload
VPN Label
36
MPLS Data Plane Operation (Prefix SID)
SRGB [16,000 – 23,999 ] SRGB [16,000 – 23,999 ] SRGB [16,000 – 23,999 ] SRGB [16,000 – 23,999 ]
Loopback X.X.X.X
Prefix SID Index = 41
A B C D
Payload
16041
Payload
Push
Push
Swap Pop
Payload Payload
VPN Label
16041
VPN Label
Pop
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Payload
VPN Label
37
MPLS Data Plane Operation (Adjacency SIDs)
Payload
16041
Payload
Push
Push
Push
Pop Pop
Payload Payload
VPN Label
16041
VPN Label
Pop
Adjacency
SID = 126
126
A B X D
BRKRST-2124
Loopback X.X.X.X
Prefix SID Index = 41
SRGB [16,000 – 23,999 ] SRGB [16,000 – 23,999 ] SRGB [16,000 – 23,999 ] SRGB [16,000 – 23,999 ]
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
MPLS LFIB with Segment Routing
• LFIB populated by IGP (ISIS / OSPF)
• Forwarding table remains constant (Nodes + Adjacencies) regardless of number of paths
• Other protocols (LDP, RSVP, BGP) can still program LFIB
38
PE
PE
PE
PE
PE
PE
PE
PE
P
In
Label
Out
Label
Out
Interface
L1 L1 Intf1
L2 L2 Intf1
… … …
L8 L8 Intf4
L9 L9 Intf2
L10 Pop Intf2
… … …
Ln Pop Intf5
Network
Node
Segment Ids
Node
Adjacency
Segment Ids
Forwarding
table remains
constant
BRKRST-2124
Traffic Protection
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Topology Independent LFA (TI-LFA) – Benefits
• 100%-coverage 50-msec link and node protection
• Simple to operate and understand• automatically computed by the IGP
• Prevents transient congestion and suboptimal routing• leverages the post-convergence path, planned to carry the traffic
• Incremental deployment• also protects LDP traffic
40BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Topology Independent LFA – Implementation
• Leverages existing and proven LFA technology• P space: set of nodes reachable from node S (PLR) without using protected link L
• Q space: set of nodes that can reach destination D without using protected link L
• Enforcing loop-freeness on post-convergence path• Where can I release the packet?
At the intersection between the post-convergence shortest path and the Q space
• How do I reach the release point?By chaining intermediate segments that are assessed to be loop-free
41BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
1000
TI-LFA – Zero-Segment Example
• TI-LFA for link R1R2 on R1
• Calculate LFA(s)
• Calculate post-convergence SPT
• Find LFA on post-convergence SPT
• R1 will steer the traffic towards LFA R5
42
Packet to Z
Default metric:10
R5
R2R1
A Z
R3
Packet to Z
R4
R5
Packet to Z
prefix-SID(Z)
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
TI-LFA – Single-Segment Example
• TI-LFA for link R1R2 on R1
• Calculate P and Q spaces• They overlap in this case
• Calculate post-convergence SPT
• Find PQ node on post-convergence SPT
• R1 will push the prefix-SID of R4 on the backup path
43
Q-space
P-space
Packet to Z
prefix-SID(Z)
Packet to Z
Packet to Z
prefix-SID(Z)
prefix-SID(R4)
Default metric:10
R5
R2R1
A Z
R3
Packet to Z
R4
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
TI-LFA – Double-Segment Example
• TI-LFA for link R1R2 on R1
• Calculate P and Q spaces
• Calculate post-convergence SPT
• Find Q and adjacent P node on post-convergence SPT
• R1 will push the prefix-SID of R4 and the adj-SID of R4-R3 link on the backup path
44
P-space Q-space
1000
Packet to Z
prefix-SID(Z)
Packet to Z
Packet to Z
prefix-SID(Z)
adj-SID(R4-R3)
prefix-SID(R4)
Packet to Z
prefix-SID(Z)
adj-SID(R4-R3)Default metric:10
R5
R2R1
A Z
R3R4 R3R4
Packet to Z
BRKRST-2124
Traffic Engineering
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Traffic Engineering with Segment Routing
• Provides explicit routing
• Supports constraint-based routing
• Supports centralized admission control
• No RSVP-TE to establish LSPs
• Uses existing ISIS / OSPF extensions to advertise link attributes
• Supports ECMP
46
TE LSP
Segment
Routing
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
How Traffic Engineering Works
• Link information Distribution• ISIS-TE
• OSPF-TE
• Path Calculation
• Path Setup
• Forwarding Traffic down path• Auto-route (announce / destinations)
• Static route
• PBR
• PBTS / CBTS
• Forwarding Adjacency
• Pseudowire Tunnel select
47
IP/MPLS
Head end
Mid-point Tail end
TE LSP
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Stateful PCE
• PCE maintains topology and path database (established paths)
• More optimal centralized path computation
• Enables centralized path initiation and update control
• Well suited for SDN deployments
48
PCEP
Stateful PCE
TED
LSP DB
PCC
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Topology Acquisition
• An external PCE requires some form of topology acquisition
• A PCE may learn topology using BGP-LS, IGP, SNMP, etc.
• BGP-LS characteristics• aggregates topology across one or more domains
• provides familiar operational model
• New BGP-LS attribute TLVs for SR • IGP: links, nodes, prefixes
• BGP: peer node, peer adjacency, peer set
49
Domain 1 Domain 2
Domain 0
BGP-LS
TED
BGP-LS BGP-LS
RR
PCE
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Active Stateful PCE
• PCC or PCE may initiate path setup
• PCC may delegate update control to PCE
• PCC may revoke delegation
• PCE may return delegation
50
PCEP
Active Stateful PCE
TED
LSP DB
Stateful
PCC
PCE has update
control over
delegated paths
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public 51
Active Stateful PCEPCE-Initiated and PCC-Initiated LSPs
• PCE part of controller architecture managing full path life cycle
• Tighter integration with application demands
PCEP
PCC-Initiated (Active Stateful PCE)
TED
LSP DB
Stateful
PCC
PCEP
PCE-Initiated (Active Stateful PCE)
TED
LSP DB
Stateful
PCC
PCC initiates
LSP and
delegates
update
control
PCE initiates
LSP and
maintains
update control
PCC may initiate path setup based on distributed network state
Can be used in conjunction with PCE-initiated paths
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
PCE Extensions for Segment Routing (SR)• Segment routing enables source routing
based on segment ids distributed by IGP
• PCE specifies path as list of segment ids
• PCC forwards traffic by pushing segment id list on packets
• No path signaling required
• Minimal forwarding state
• Maximum network forwarding virtualization
• The state is no longer in the network but in the packet
• Paths may be PCE- or PCC-initiated
52
PCEP
Segment List:: 10,20,30,40
Stateful PCE
TED
LSP DB
Stateful
PCC
Node
SID
Adjacency
SID
Forwarding
table remains
constant
In Out Int
L1 L1 Intf1
… … …
L7 L7 Int3
L8 Pop Intf3
… … …
L9 Pop Intf5
ApplicationPath
Request
BRKRST-2124
Conclusion
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Conclusion
• 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
Recommended Follow-up Session:Segment Routing: Technology and Use-cases (BRKRST-3122)
54BRKRST-2124
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Segment Routing Sessions
• Introduction to Segment Routing (BRKRST-2124)
• Segment Routing: Technology and Use-cases (BRKRST-3122)
• Application Engineered Routing: Allowing Applications to Program the Network (BRKSPG-2066)
• Segment Routing in Datacenter using Nexus 9000/3000 (BRKDCN-2050)
• Cisco WAN Automation Engine (WAE) Network Programmability with SR (LTRMPL-2104)
• Segment Routing in Datacenter using Nexus 9000/3000 (LABRST-2020)
• Next Generation Service Provider Network using Segment Routing & BIER (LABSPG-2012)
• DevNet Workshop – Application Engineered Egress Routing (DEVNET-2062)
• DevNet Workshop – Enabling Containers to Leverage SR (DEVNET-2063)
Cisco Live 2016
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Continue Your Education
• Demos in the Cisco campus
• Walk-in Self-Paced Labs
• Table Topics
• Meet the Engineer 1:1 meetings
• Related sessions
58BRKRST-2124
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Backup Slides
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
IS-IS Configuration
• Required• Wide metrics
• SR enabled under unicast address family
• Optional• Prefix-SID configured under loopback(s) AF IPv4
• MPLS forwarding enabled automatically on all (non-passive) IS-IS interfaces
• Adjacency-SIDs are automatically allocated for each adjacency
61BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
router isis DEFAULT
net 49.0001.1720.1625.5001.00
address-family ipv4 unicast
metric-style wide
segment-routing mpls
!
interface Loopback0
passive
address-family ipv4 unicast
prefix-sid absolute 16041
!
!
interface GigabitEthernet0/0/0/0
point-to-point
address-family ipv4 unicast
!
!
!
62
Configuring Segment Routing for IPv4 Using IS-IS (Cisco IOS XR)
Enable Segment Routing for IPv4 with
MPLS data plane
Advertise prefix SID 16041 (index 41) for
Loopback0
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
router isis DEFAULT
net 49.0001.1720.1625.5001.00
address-family ipv6 unicast
metric-style wide
segment-routing mpls
!
interface Loopback0
passive
address-family ipv6 unicast
prefix-sid absolute 16061
!
!
interface GigabitEthernet0/0/0/0
point-to-point
address-family ipv6 unicast
!
!
!
63
Configuring Segment Routing for IPv6 Using IS-IS (Cisco IOS XR)
Enable Segment Routing for IPv6 with
MPLS data plane
Advertise prefix SID 16061 (index 61) for
Loopback0
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
OSPF Configuration
• OSPFv2 control plane
• Required• Enable segment-routing under instance or area(s)
• Command has area scope, usual inheritance applies
• Enable segment-routing forwarding under instance, area(s) or interface(s)• Command has interface scope, usual inheritance applies
• Optional• Prefix-SID configured under loopback(s)
• MPLS forwarding enabled on all OSPF interfaces withsegment-routing forwarding configured
64BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
router ospf DEFAULT
router-id 172.16.255.1
segment-routing mpls
segment-routing forwarding mpls
area 0
interface Loopback0
passive
prefix-sid absolute 16041
!
interface GigabitEthernet0/0/0/0
network point-to-point
!
!
!
65
Configuring Segment Routing for IPv4 Using OSPF (Cisco IOS XR)
Enable Segment Routing with MPLS data
plane
Advertise prefix SID 16041 (index 41) for
Loopback0
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
router isis DEFAULT
net 49.0001.1720.1625.5001.00
address-family ipv4 unicast
metric-style wide
segment-routing mpls
!
interface Loopback0
passive
address-family ipv4 unicast
prefix-sid absolute 16041
!
!
interface GigabitEthernet0/0/0/0
address-family ipv4 unicast
fast-reroute per-prefix
fast-reroute per-prefix ti-lfa
!
!
!
66
Configuring Topology Independent Fast Reroute for IPv4 using Segment Routing and IS-IS (Cisco IOS XR)
Enable TI-LFA for IPv4 prefixes on
interface GigabitEthernet0/0/0/0
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
router isis DEFAULT
net 49.0001.1720.1625.5001.00
address-family ipv6 unicast
metric-style wide
segment-routing mpls
!
interface Loopback0
passive
address-family ipv6 unicast
prefix-sid absolute 16061
!
!
interface GigabitEthernet0/0/0/0
address-family ipv6 unicast
fast-reroute per-prefix
fast-reroute per-prefix ti-lfa
!
!
!
67
Configuring Topology Independent Fast Reroute for IPv6 using Segment Routing and IS-IS (Cisco IOS XR)
Enable TI-LFA for IPv6 prefixes on
interface GigabitEthernet0/0/0/0
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
router isis DEFAULT
net 49.0001.1720.1625.5001.00
address-family ipv4 unicast
metric-style wide
segment-routing mpls
segment-routing prefix-sid-map receive
segment-routing prefix-sid-map advertise-local
!
...
!
segment-routing
address-family ipv4
prefix-sid-map
172.16.255.1/32 4041 range 8
!
!
!
68
Configuring a Mapping Server for SR and LDP Interworking for IPv4 Using IS-IS (Cisco IOS XR)
Local prefix-to-SID mapping policy
172.16.255.1/32 – 4041
:
172.16.255.8/32 - 4048
Construct active mapping policy using
remotely learned and locally configured
mappings (mapping client)
Advertise local mapping policy (mapping
server)
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
router isis DEFAULT
net 49.0001.1720.1625.5001.00
address-family ipv4 unicast
metric-style wide
segment-routing mpls
segment-routing prefix-sid-map receive
!
interface Loopback0
passive
address-family ipv4 unicast
prefix-sid absolute 16041
!
!
interface GigabitEthernet0/0/0/0
point-to-point
address-family ipv4 unicast
!
!
!
69
Configuring a Mapping Client for SR and LDP Interworking for IPv4 Using IS-IS (Cisco IOS XR)
Construct active mapping policy using
remotely learned and locally configured
mappings (mapping client)
BRKRST-2124
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
Enabling Segment Routing FeatureNXOS
feature bgp
install feature-set mpls
feature-set mpls
feature mpls l3vpn
feature mpls segment-routing
Under Interface configuration:
mpls ip forwarding
Commands:
BRKRST-2124 70
Thank you