SDN in SP WAN
TECH-SDN-SP
David Jakl
Systems Engineer
Agenda
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SDN in SP WAN
Multi-Layer SDN
PCEP
BGP Link State
BGP Flowspec
Segment Routing
Summary
SDN enables IP/MPLS evolution to a hybrid control-plane
centralized control improves network operations and optimization
Applications
Applications
Applications
Applications
Controller
Evolution
• Distributed Control remains best for many use-cases; e.g. IGP convergence
• Centralized Control introduces new value; e.g. TE placement optimization
4
SDN WAN Transport – Use Cases
Optimization
• Global Load Balancing
• Multi Layer Optimization
• Coordinated Maintenance
• LSP splitting and merging
• Network Rearranging
• Segment Routing
Monetization
• Bandwidth Calendaring with Hybrid Cloud
• Premium Bandwidth
• Path Diversity
• Latency Based Forwarding
5
hourly
daily
weekly
monthly
quarter
annual
Traffic change frequency
Another Perspective of Offline vs Online SDN WAN
Orchestration
SDN WAN
(online)
Planning
(offline)
25%
50%
Load / Link
75%
100%
 When the planning inputs change almost on a hourly basis and the network
load is close to the max-link-load objective
Source: Clarence Filsfils
6
Our SDN WAN Orchestration Platform Evolving …
Apps
NB API
Orchestration
Optimization &
Prediction
Analytics
Plan
Calendaring
RESTCONF
Collector
Deployer
IPv4/IPv6/MPLS
Segment Routing
Optical
7
SDN WAN Orch Use-Case #5: Maintenance Window Scheduling
2
4
3
Ops
NB API
SDN WAN Orch
Collector
1
Deployer
PCEP
WAN
5
① Network conditions reported to
collector
② Ops selects Ra, Rb and maint
window time
③ Maint Window request:
<Ra, Rb, Window>
④ SDN W-O returns impact and
changeover plan. Ops confirms
⑤ At Maint Win start SDN W-O rearranges traffic to bypass Ra, Rb
R2
R1
Customers
Ra
Rb
R3
DC/Clouds
8
The Multi-Layer Optimization – nLight
 The new DWDM layer enables a truly Converged IP+Optical Transport
 Scalable more than 8Tb/s per fiber, based on 100+Gb/s DWDM channels
 Flexible, fully non-blocking wavelength switching
BUT…
– Past: Optical BW was relatively cheap  throw optical BW at the problem
– Future: Optical BW most expensive part of CapEx  need to use it efficiently
 SDN transport enables Converged network optimization
– SLA aware routing (e.g. min Latency) or Cost aware routing (e.g. min regens)
– Link failure Restoration can lead to 20+% savings, by reusing available router ports
 SDN innovation most important for Converged Transport
 The IP/MPLS evolution to SDN is an important innovation!
SDN
Controller
(WAN O)
 Optical control, always mainly centrally controlled (NMS)!
9
Multi-Layer IP/Optical PCE Models (Examples)
 Single-Layer PCE
– Visibility into L3 and optical
topologies
– Programs L3 and L3 UNI to
optical
 Separate PCE
– Operates on each layer
– Optional inter-layer PCE
communications
VNT M = Virtual Network T opology Manager
10
SDN WAN Use-Case #9: SDN WAN Orch Triggered
GMPLS Setup
① Realtime data collection
reveals trending congestion
(Rc-Rb link) imminent
② Ops App requests Multi-layer
optimization
③ SDN W-O programs Ra and Rb
to initiate GMPLS Setup
④ New Ra-Rb link is injected into
IP/MPLS Topology
ML Path
Optimization App
2
1
NB API
Ops
SDN WAN Orch
Collector
Deployer
PCEP
3
Rc
Congested!!
4
R1
Ra
GMPLS UNI
O1
Rb
GMPLS UNI
R2
O2
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PCEP
BGP Link State
BFP Flowspec
12
PCE Architecture
 Addresses complex requirements for path computation in large, multi-domain and multi-layer networks
 Path computation element (PCE)
–
Computes network paths based on network information (topology, paths, etc.)
–
Stores TE topology database (synchronized with network)
–
May reside on a network node or on out-of-network server
–
May initiate path creation
–
Stateful - stores path database included resources used (synchronized with network)
–
Stateless - no knowledge of previously established paths
HELLO
my name is
PCE
 Path computation client (PCC)
–
May send path computation requests to PCE
–
May send path state updates to PCE
 PCC and PCE communicate via Path Computation Element Protocol (PCEP)
 Cisco innovation, standardization started in 2005
 First implementation (stateless PCC/PCE on network nodes) released in IOS XR 3.5.2 for inter-area TE
 Cisco WAN orchestration provides network path instantiation driven by an out-of-network stateful PCE
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Stateful PCE
Stateful PCE
 Introduces PCEP extensions for
LSP DB
– LSP state synchronization betw een PCCs and PCEs
– PCC delegation of LSP control to PCE
TED
 Passive stateful PCE
– PCC maintains state synchronization w ith PCE
– PCC exclusively controls LSP
– PCE does not modify LSP state
PCEP
 Active stateful PCE
– PCC maintains state synchronization w ith PCE
– PCC may delegate LSP control to PCE
 Either PCE or PCC can initiate LSP setup
PCC
PCE-initiated
LSP
 PCC always owns LSP state
 Cisco WAN orchestration solution relies on an active stateful PCE that initiates LSP setup
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BGP Link State
 BGP may be used to advertise link state and
link state TE database of a network (BGPLS)
 Provides a familiar operational model to
easily aggregate topology information across
domains
 New link-state address family
 Support for distribution of OSPF and IS-IS
link state databases
 Topology information distributed from IGP
into BGP (only if changed)
 Support introduced in IOS XR 5.1.1
 draft-ietf-idr-ls-distribution
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BGP Flowspec
for SDN WAN Orchestration
 Define classification and action semantics in
BGP called Flow Specifications (Flowspec)
 Leverage BGP control plane and transport
for efficient, scalable flowspec
announcements and withdrawls
 Enhanced actions:
–
–
–
–
Traffic-rate
Traffic-action (includes sampling, logging)
Redirect (NH, VRF)
Traffic-marking (DSCP)
 RFC 5575
 IOS XR 5.2.0
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OffRamp in “Dirty” VRF: How FlowSpec helps?
More granular, only the protocol/port/packet-size… is diverted in Dirty VRF
•
Simple and scalable
VRF dirty
0.0.0.0/0
nh: @TMS
BGP FS
Match: dest-IP: 2.1.1.1
+ dest-port: 80
Action: NH: VRF Dirty
@TMS
J
S
RR
IPv4
Match: dest-IP: 2.1.1.1
I
+ dest-port: 80
Action: NH: VRF Dirty
F
Victim
2.1.1.1
L
H
E
C
K
G
D
B
M
VRF dirty
0.0.0.0/0
nh: @TMS
static
BGP FS
Controller
static
•
A
Segment Routing
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Balance of Distribution and Centralization
Distribution-only
RSVP-TE
Non-optimum, non-predictable,
and experienced as too complex
Balance
Centralized-only
OpenFlow
Scalability?
Deployability within
18months?
Much
More !
Confirmed Operators: Orange, Facebook, Google, Telstra,
Goldman, BT, Belgacom, TW, Comcast, Liberty, SFR…
Interested Operators: DT, TI, Telefonica, Cox, Century Link,
One-year
Reuters, Barclays, Sky…
Cisco
first-public
presentation
DC2WAN
birth day
demo
SR/TE first
public demo
Confirmed use-cases: SDN/TE, FRR,presents
EPE, DC,
service integration, Access/MetroE TI-LFA w ith
XR and
Cisco NAG
Operator
Group
Formed
Oct12
Cisco
Cisco
releases a
presents SR
XE
roadmap total of 8 IETF
at MPLS WC
drafts on SR
w ith demo
Cisco
releases 2
IETF drafts
on SR
12 IETF drafts
SPRING WG
JNPR j oins
More !
15 IETF drafts
FCS SW
ALU/Ericsson
j oin
Mar13
Jul13
Nov 13
Mar14
Jul14
Nov 14
www.segment-routing.net
Nodal segment to C
Nodal segment to C
A
B
C
D
Adj Segment
M
N
O
Z
P
Nodal segment to Z
• Simple extension to IS-IS or OSPF, automatically builds and maintains Segments
Nodal Segment – A Shortest path to the related node
Adjacency Segment – One hop through the related adjacency
• Excellent Scale: a node installs N+A FIB entries
N = nodal segments; A = adjacency segments
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FEC Z
push 65
A
swap 65
to 65
swap 65
to 65
B
pop 65
C
D
Z
Packet to Z
65
65
65
Packet to Z
Packet to Z
Packet to Z
65
Packet to Z
A packet injected anywhere
with top label 65 will reach Z
via shortest-path
• Node Z advertises its node segment (loopback 0)
e.g. in ISIS its just a simple ISIS sub-TLV extension
• All remote nodes install the node segment to Z in the MPLS dataplane
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A
B
C
D
Pop
9003
M
N
O
Z
P
A packet injected at node C
with label 9003 is forced
through datalink CO
• Node C allocates a local label for CO link segment
• C advertises the adjacency label in IGP
e.g. for ISIS, it’s a simple sub-TLV extension
• C is the only node to install the adjacency segment in MPLS dataplane (FIB)
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• Source Routing along with the explicit
path, stack of nodal and adjacency
segments
• Any explicit path can be expressed:
e.g. ABCOPZ
72
72
9003
9003
9003
65
65
65
Packet to
Z
Packet to
Z
Packet to
Z
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• ECMP
Node segment
A
72
B
C
D
9003
Z
• Per-flow state only at head-end
not at midpoints
• Source Routing
the path state is in the packet header
M
N
O
P
65
Packet to Z
65
65
65
Packet to Z
Packet to
Z
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A
B
PE2
PE1
M
N
All VPN services ride on the node segment
to PE2
IPv4 over MPLS/IGP
VPN over MPLS/IGP
Internet over MPLS/IGP
PW over MPLS/IGP
IPv6 over MPLS/IGP
• Efficient packet networks leverage ecmp-aware shortest-path!
node segment!
• Simplicity
no complex LDP/ISIS synchronization to troubleshoot
one less protocol to operate
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PE
PE
PE
PE
PE
PE
P
PE
• SR router scales much more than with RSVP-TE
The state is not in the router but in the packet
Node + Adj vs. Node^2
• No requirement of RSVP-TE protocol
And knobs such as LDPoRSVP etc.
Node
Segment
Ids
Adjacency
Segment
Ids
PE
In Label
Out Label
Out
Inter face
L1
L1
Intf1
L2
L2
Intf1
…
L8
L9
…
L8
Pop
…
Intf4
Intf2
L10
Pop
Intf2
…
…
…
Ln
Pop
Intf5
FIB
remains
constant
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draft-francois-segment-routing-ti-lfa
• Guaranteed Link/Node FRR in any topology
Backbone
even w ith asymmetric metrics
• No Directed LDP session
C1
• Simplicity
C2
entirely automated (no need for customization)
• Incremental deployment
E1
E4
Applicable to LDP and IP primary traffic
Only the repair tunnel is SR-based
• For networks with symmetric metric & link protection
No extra computation
Simple repair stack
1000
E2
E3
Node segment
to P node
Adj segment
to Q node
Node segment to P node
Adjacency segment from P to Q
• Demo available
Default metric: 10
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28
SR with WAN Orchestration
 WAN O allows for the best possible simplification of SR
– Optimum state computation
– A single touch-point at the Source Node
– Instant set-up time
Ask for path to G
w ith certain SLA
(delay, bandw idth,
duration, etc)
 Also a stateful PCE, as with MPLS-TE, can be help to:
– Compute globally optimum paths for traffic-engineered SR tunnels
1
B
– Instantiate SR tunnels based on requests from applications
– Instantiate traffic steering onto the instantiated tunnel
F
0
D
C
G
E
A
 Minimal changes
–
–
–
–
–
PCEP capability to negotiate SR between PCE and PCC
IGP capability used by PCE’s to advertise their SR/PCE capability
Extension to BGP-LS to convey the segments
Extension to IR2S policy retrieval to include segment information
Minimal changes in (Cisco) CLI and look and feel stays same
SDN WAN O
Indentify best
path and
segments (B, D,
C, E, G)
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Summary
30
Summary
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SDN WAN
PCEP
BGP Link State
BGP Flowspec
Segment Routing
Technology Objectives
Configurable Networks
Orchestrated Networks
Apps-aware Networks
Network-aware Apps
Network Interfaces
Programmatic Interfaces (& Overlays)
Simplify Networks
Segment Routing,
IP+Optical Convergence
M ake everything go faster, easier and more agile
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Scenario 1: Using ECMP
Scenario 2: Using One Path of
ECMP
Scenario 3: Using Anycast
Segment
Scenario 4: Not Using
Shortest Path
Scenario 5: Traversing Links
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