Core IP Routing and Switching Technology - Cvt-dallas.org

Core IP Routing and
Switching Technology
February 18, 2003
Tom McDermott
Chiaro Networks
Richardson, Texas

Outline
• Changes in the Carrier Market
• Evolution leading to cost overhead
• Approaches to Network Cost Reduction
– Combine multiple services onto one
network
– Collapse multiple layers of the network
• An IP approach to consolidation
• Technologies Involved to build a large IP
Router / MPLS Switch
– Switch Fabric
– Reliability and Redundancy
– General Purpose (Soft) Packet Processing
2

Market Change: Total Implosion
• Data revenue per bit still going down
• Data traffic still growing
• Voice revenue stabilizing
• It’s not best effort traffic that foots the bill.
• Need Revenue-per-bit > Cost-per-bit
• Must simultaneously:
– Drive equipment cost down
– Less expensive equipment or
– More efficient network design
– Drive operational costs down
– Do more with less complexity
– Provide services with better revenue
profile than best-effort: VPN, VoIP, etc.
3

Where We are Today
• A lot of legacy equipment – designed first to
support TDM then adapted to fit packets.
• Must cross multiple layers to transit the core:
– Outside plant fiber, DWDM transmission
– SONET/SDH multiplex equipment
– Crossconnect equipment (protection, grooming)
– Routing and Switching equipment
• Multiple service devices
– Frame Relay
– ATM
– Ethernet MAN
– Packet over SONET (POS)
– Everything over MPLS (soon…)
• Trend: IP over Everything, Everything over IP 1
– over MPLS?
1
Vint Cerf, Worldcom
4

Backbone Architecture: Old & New
SDH/
SONET
Legacy Network
Circuit Protection
Transport Layer
Next Generation Network
Optical Mesh(& Link) based
GMPLS Protection,
Wavelength-based VPN
OXC
Circuit Grooming & Protection
EXC
EXC
Circuit-based Grooming
Circuit-based VPN
GMPLS Protection?
Core
Router
Aggregation
Packet-based Grooming
Packet-based VPN
Packet Aggregation
(fan-out)
MPLS Grooming
MPLS Switching
Packet-based Grooming
Packet-based VPN
Packet Aggregation
IP /
MPLS
Core
Router
Service
Service
Circuit-switched
voice, data services
VoIP, VPN, Etc.
Service
Service
5

Next Generation Backbone
Network Trends
• Conversion of the backbone network from
circuits to packets is in process
– Fine-grained grooming, aggregation, compression,
switching, and protection is less expensive using
packet technology.
– Data traffic is already IP (although it may be carried by
ATM or FR). VPN desires good TCP performance.
–Voicetraffic slowly starting to migrate to IP
– New long-haul transmission spans going regeneratorless,
and protection-less to reduce cost.
– Debate: switching λ or routing packets?
– Routing packets provides more value-add for carrier
6

Next Generation Backbone
Network Issues - 1
• Truly scalable, reliable packet routers not available
– Clustered routers used for scale today
–Duplicatedrouters used for redundancy today
→ Scalable, reliable router needed
• Protection of simplified spans requires networkwide
solution
– Several approaches:
– Link:
– Protection in the network elements (works also
for legacy spans), ~MPLS-FRR
–Mesh:
– Optical Crossconnect
– Electrical Crossconnect
–MPLS, GMPLS
7

Next Generation Backbone
Network Issues - 2
• Multimedia traffic requires delay and jitter
control (deterministic)
–Approaches:
– Over-provision links
– Hope TCP does not overload, avoid downstream
TCP merge
– Groom traffic (MPLS)
– Keep TCP out of real-time links
– QoS for real-time traffic
– Restrict TCP’s share of bandwidth on a link
→ Need router with traffic management and/or large size
8

Next Generation Backbone
Network Issues - 3
• VPN requires cost/performance tradeoff knobs
(gold, silver, bronze)
– Approaches
– Supply an entire λ (very expensive)
– Electrical multiplexing (expensive, inflexible)
– Packet multiplexing (efficient, flexible, but large
management effort)
– Use packet QoS markers for drop probability,
packet rate-limiting to assure service
– Mark at the edge, tunnel through the core
– Tandem switching architectures scale better
for large networks than a flat core
9

Proposed Network Solutions
• Peer (integrated) transport & packet
networks
– GMPLS provides integrated control-plane
– Issue: all switch-able NE’s require huge routing tables,
intelligent control processor
• Overlay (separated) transport & packet
networks
– Transport layer provides UNI 1.0 API to packet layer
– Issue: NE auto-discovery, IP-to-physical binding
• GMPLS: envisioned for λ switching
– Cost / Benefit tradeoff: another layer vs. lower cost
transparent switch points
– Small-medium networks: poor
– Huge networks: may work
10

Technologies - 1
• Large Routers:
– Require large, fast, non-blocking switch fabric
– Traditional approaches (electronic crossbar, shared
memory) have not scaled very well past 300 Gb/s
– Per-trace bandwidth, Memory bandwidth
limitations
– Distributed Switches are being tried
– Concerns about fault tolerance, rerouting, delay,
reconfiguration difficulty
– New approaches
– High-speed signal I/O (3.125 10 Gb/s per pin)
– All-optical Fabrics – need to switch fast
– Difficult to schedule efficiently
– Need massively parallel scheduling engine
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Crossbar Switching Architecture
Network
Proc.
Line
Card
Crossbar
Switch
Network
Proc.
Line
Card
• Large crossbar switch
can provide scale and
performance
• Redundancy needed
between internal
components
Network
Proc.
Line
Card
Network
Proc.
Line
Card
Global
Arbitration
Optical
Electrical
12

Optical Phased Array –
Multiple Parallel Optical Waveguides
Output
Fibers
• • •
WG #1 WG #128
Air Air Gap Gap
Input
Optical Fiber
13

Optical Switch Die
18 Beam Deflectors per Die
128 Waveguides per Beam Deflector
Magnified
View
0.5 inches
1.2 inches
Flip-chip
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64 x 64 Optical
Switch
• 72 Beam Deflectors
• 30 nanosecond switching
speed
• Optically transparent
• Lab test at 160 Gb/s per
fiber (AT&T Labs)
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Technologies - 2
• Reliable Routers:
– Must be highly reliable
– Avoid duplication of routers, transmission and
operations costs
– Avoid clustering interconnect cost and extra faults
– One approach is an architecture that resembles a
Class 4 tandem switch.
– Cost effective due to internal 1:N redundancy
– Careful design to avoid single-point faults
– Software outages and protocol state loss can be well
addresses with stateful protection and recovery
(backwards compatible to existing routers).
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Technologies - 3
• High-Performance and Flexibility
– Must run at wire-speed
– Packet forwarding and MPLS switching at line rate
– Able to alter function of line card
– Changes in protocols
– Traffic Management and Classification
– Migrate to different service profiles
– MPLS label handler (push, pop, swap)
– Router control must not bog down as the system
scales
– Some autonomy to packet processing
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Technology: Soft Packet Processing
• 2.5 Gb/s and 10 Gb/s Packet Processor Engines
• ‘Soft’ processing of packets
• IPv4 ( IPv6), FR, ATM, MPLS
• Programmable Traffic Management
• Classification processor: look-aside
• VOQ in hardware
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Summary
• Cost reduction and Revenue
enhancement critical to operators
• Network model has to change:
– Eliminate layers in the network
– Converge parallel networks
– Reduce NE duplication via High Availability
• Enhance better revenue-profile services
– Provide appropriate service profile for each
class of service
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