packet optical integration plans for otn and mpls switching technologies
DESCRIPTION
Following a period of intense research activities with our main vendors and the definition of our mid-to-long term strategy, Colt has started a project to execute the integration of the long-haul DWDM L1, the Carrier Ethernet L2 and the IP L3 layers into a single platform. Our presentation at WDM & Next Generation Optical Networking 2012 examines in particular the reality of circuits versus packets at Colt as well as two hot cases in the industry: router by-pass and OTN switching versus MPLS switching.TRANSCRIPT
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© 2012 Colt Telecom Group Limited. All rights reserved.
Packet optical integration plans for OTN and MPLS switching technologies
Network & IT Platform Strategy and Architecture
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Contents
1 Three separate networks today
2 Benefits to integrate L1 & L2 & L3 onto one network
3 Review of integration plans and packet optical
5 Router by-pass and OTN versus MPLS switching
4 Circuits and OTN as the serving layer
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A network of depth and breadth
• High capacity long distance network - 35,000km
• Connecting 21 countries, 39 metro networks and >100 cities
• 19 (+1) data centres and 18,000 connected buildings
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Network layer integration – Historical situation
NB: Colt managed CPE (not customer’s)
L2 packet core
L3 packet core
L3 service
L3 CPE
IP services over Ethernet access (metro)
Ethernet services (metro & inter-metro)
L2 access &aggregation
L3 PE
L2 PEL2 service
L2 CPE
L2 CPE
L2 serviceIP NNI
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Benefits associated with network integration
Improved service unit costs (CAPEX/OPEX reduction, statistical multiplexing), better delivery lead time and TTR, L2 & L3 service blending (Integrated Routing & Bridging on PE)
Statistical multiplexing gain in the core
Reduced CAPEX (less devices per service, “pay as you grow” core) and OPEX (simplified delivery & assurance)
Operations, architecture, service nodes (PEs)Simplification
Technical
Product
Cost
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Network layer integration – L2/L3 CPE
L2 packet core
L3 packet core
L2 access &aggregation
L3 PE
L2 PEL2 service
L2 CPE
L2 CPE
L2 serviceIP NNI
L3 service
L3 features moving to the PE layer
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Network layer integration – L2/L3 edge
L2 packet core
L3 packet core
L2 access &aggregation
L2 service
L3 service
L2 service
L2 CPE
L2 CPE
L2/L3 PE
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Network layer integration – L2/L3 packet optical core
L2 access &aggregation
L2 service
L3 service
L2 service
L2 CPE
L2 CPE
L2/L3 packet optical core
L2/L3 PE
L3 featuresL3 features moving to the
core layer / cloud
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Vision on the best packet optical platform
• Multi-layer switching platform– WDM (colour-less, contention-less, etc.)
– OTN
– Packet
• OTN switching– Fill-in the high speed waves
• Packet switching– MPLS switching (LSR)
– No LER (VPN, VPLS, GRE, MC), no BGP
– CP protocols (IS-IS, OSPF, TE, LDP, RSVP)
L2/L3 packet optical core
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Network layer integration – Design thoughts
Network design considerations
•L2 and L3 services integrated on the same physical infrastructure but kept logically separated through the use of dedicated VLANs
– Service QoS characteristics uncompromised thanks to no queue sharing (8xL2 queues + 8xL3 queues)
•Key protocols for L2 and L3 services
•No mandatory requirement of MPLS-TP for L2 services– To start with MPLS properly tuned seen good for the job (OAM included)
– … but over time MPLS-TP might be useful for service assurance activities
Functions L2 services L3 services
IGP OSPF IS-IS
Path computation NMS/OSS based IGP (core)
Topology discovery OSPF-TE (booked bandwidth) IGP
Path creation ERO + RSVP-TE IGP + LDP
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The reality of circuits versus packets at Colt
• Demand for SDH services (2.5 and 10Gbps) still exists– No foreseeable time for end of sale (not within the next 2 years)
– But largely outnumbered by Ethernet services (1 and 10Gbps)
• No demand for OTN services (wholesales) exists– And no early signs this is going to change
– But OTN switching capability (as an internal network feature) remains attractive
• High speed Ethernet services (1 and 10Gbps point-to-point) are provisioned over the optical transport layer– But 1 and sub-10Gbps are being moved to the MPLS packet transport layer as scale of
this layer increases
• Sub-1Gbps Ethernet, IP and VoIP services are provisioned over MPLS– Integrated packet optical core to become more prominent in the future
Proportion of circuits decreasing over time
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Circuits supported by different flavours of OTN
• OTN framing– Proven track record with G.709 digital wrapper with FEC
– Even used in packet platforms (IP over WDM with coloured optics)
• OTN multiplexing– Must have LO ODU to efficiently fill-in waves in point to point topology
1G circuits
10G wave
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Circuits supported by different flavours of OTN
• OTN framing– Proven track record with G.709 digital wrapper with FEC
– Even used in packet platforms (IP over WDM with coloured optics)
• OTN multiplexing– Must have LO ODU to efficiently fill-in waves in point to point topology
• OTN switching– Useful to more efficiently use waves in transit situations (bus topology)
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Circuits supported by different flavours of OTN
• OTN framing– Proven track record with G.709 digital wrapper with FEC
– Even used in packet platforms (IP over WDM with coloured optics)
• OTN multiplexing– Must have LO ODU to efficiently fill-in waves in point to point topology
• OTN switching– Useful to more efficiently use waves in transit situations (bus topology)
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Router bypass and circuit versus MPLS switching
PEPOTN
MPLS
service VLAN
transport tunnel
service tunnel
What type of inter-PE connectivity on transit sites?
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Router bypass and circuit versus MPLS switching
Router bypass not seen too hot for Colt… if technically achievable
What type of inter-PE connectivity on transit sites?
•No router bypass but MPLS switching on transit nodes– Simplified architecture hence simplified operations (less tunnels, one case policy)
– Only marginal extra costs as co-located OTN and LSR functions
– Statistical multiplexing benefit (assuming minimum traffic variability)
– Additional latency reasonably negligible
– Potential scale concerns for large tier-1
•Router bypass i.e. circuit switching on transit nodes– Challenge to map inner LSP transport tunnel to separate circuit (burn dedicated ports
on P and OTN as an expensive mitigation step)
– Circuit bandwidth tax (more controllable if using low granularity ODUFlex)
– Better latency in general (unless store & forward mapping scheme used)
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Summary
• Packet transport layer likely to become the pivotal transport layer– Services run packets and use only 1/15th of their contracted bandwidth
• Great stories in optics to bring in 100G+, SD-FEC, flexible grid, etc.– Unclear rationale to massively scale the optical and OTN layers if the network
would run no actual traffic
• Different implementation scenarios for packet optical– LSR switching on optical core (with packet CP) or, in a later timescale,
Software Defined Networks controller (ONF or IETF definition)
MPLS switching: yes
OTN switching (infra): yes today
Decision factors: demand, scale, pricing