segment routing overview and demonstration - frnogmedia.frnog.org/frnog_21/frnog_21-3.pdf · ....
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© 2011 Cisco and/or its affiliates. All rights reserved. 1
Segment Routing
Jérôme DURAND – Consulting Systems Engineer [email protected] - http://reseauxblog.cisco.fr
FRNOG #21 – 20 septembre 2013
© 2013 Cisco and/or its affiliates. All rights reserved. – [email protected] 2
Simplicity
Programmability
Traffic Engineering
Scalability and FRR
Re-
Use
© 2011 Cisco and/or its affiliates. All rights reserved. 5
Technology
The application controls, the network delivers
The state is no longer in the network but in the packet
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• Nodes advertise a node segment
– simple IGP extension
• All remote nodes install node segment ids in data plane
A packet injected anywhere
with top label 65 will reach Z
via IGP shortest path A B C
Z
D
65
FEC Z
push 65 swap 65
to 65
swap 65
to 65 pop 65
Packet
to Z
Packet
to Z
65
Packet
to Z
65
Packet
to Z
65
Packet
to Z
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• Nodes advertises adjacency label per link
– simple IGP extension
• Only advertising node installs adjacency segment in data plane
• Enables source routing along any explicit path (segment list)
B C
N O
Z
D
P
A
9101
9105
9107
9103
9105
9101
9105
9107
9103
9105
9105
9107
9103
9105
9107
9103
9105
9103
9105
9105
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• Source Routing
• Any explicit path can be expressed: ABCOPZ
A B C
M N O
Z
D
P
Pop
9003
Packet to Z
65
9003
Packet to Z
65
Packet to Z
Packet to Z
65
Packet to Z
65
9003
72
Packet to Z
65
9003
72
72 72
65
65
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Path ABCOPZ is ok. I account the BW.
Then I steer the traffic on this path
FULL
66
65
68
Tunnel AZ onto
{66, 68, 65}
The network is simple, highly programmable and responsive to rapid changes
2G from A to Z please
© 2011 Cisco and/or its affiliates. All rights reserved. 11
Properties
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• Implicit leverage of all MPLS excellent properties
– standardized and widely supported dataplane
– standardized and widely supported IP control plane (ISIS, OSPF, BGP)
– multi-service capability (VPN4, VPN6, 6PE, VPLS, eVPN, PW…)
• Co-existence with MPLS as currently deployed
• Incremental deployment
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• Automation
• Fewer protocols to operate
• Fewer protocols interactions to troubleshoot
• Less state to maintain by routers
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• IP-based FRR is guaranted in any topology
– 2002, LFA FRR project at Cisco
– draft-bryant-ipfrr-tunnels-03.txt
• Directed LFA (DLFA) is guaranteed when metrics are symetric
• No extra computation (RLFA)
• Simple repair stack
– node segment to P node
– adjacency segment from P to Q
Backbone
C1 C2
E1 E4
E3 E2
1000
Node segment
to P node
Default metric: 10
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• Each engineered application flow is mapped on a path
– millions of paths
• A path is expressed as an ordered list of segments
• The network maintains segments
– thousands of segments
– completely independent of application size/frequency
• Excellent scaling with complete application un-coupling
– the application state is no longer within the router but within the packet
Millions of Applications
flows
A path is mapped on a
list of segments
The network only maintains
segments
No application state
© 2011 Cisco and/or its affiliates. All rights reserved. 16
Use Cases
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• Massive simplification
– most services just need shortest-path
• Automated 50msec FRR
A
B
Z
C D
Nodal Segment to D identified
by global label 65
65
vpn
cust vpn
cust
65
vpn
cust vpn
cust
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• A sends traffic with [65] Classic ecmp “a la IP”
• A sends traffic with [11, 65] Packet gets attracted in blue plane and then uses classic ecmp “a la IP”
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• SR Server performs
– Policy control
– Admission control (bandwidth)
– Path Computation and Segment-Combo Resolution
SR PCE From A to Z with SLA rqt
(latency, bandwdith, disjointness)
Use Segment
Combo
…
A
Z
Z
A
• Each application slice can change any of its path, any time
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Conclusion
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Simplicity
Programmability
Traffic Engineering
Scalability and FRR
Re-
Use
Thank you.
http://reseauxblog.cisco.fr