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1AC_055_2000 © 2000, Cisco Systems, Inc. Fast IP Routing Axel Clauberg Consulting Engineer Cisco Systems Axel Clauberg Consulting.

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Presentation on theme: "1AC_055_2000 © 2000, Cisco Systems, Inc. Fast IP Routing Axel Clauberg Consulting Engineer Cisco Systems Axel Clauberg Consulting."— Presentation transcript:

1 1AC_055_2000 © 2000, Cisco Systems, Inc. Fast IP Routing Axel Clauberg Consulting Engineer Cisco Systems Axel Clauberg Consulting Engineer Cisco Systems

2 2AC_055_2000 © 2000, Cisco Systems, Inc. Agenda The Evolution of IP Routing Transmission Update: 10GE Router Architectures So, its all just speed ?

3 3AC_055_2000 © 2000, Cisco Systems, Inc. The Evolution of IP Routing

4 4AC_055_2000 © 2000, Cisco Systems, Inc. Heard around the corner ? IP Routers are slow, sw-based IP Routers cause high latency IP Routers are undeterministic IP Routers do not support QoS

5 5AC_055_2000 © 2000, Cisco Systems, Inc. WAN Customer Access Speed Evolution Late 1980s: 9.6 Kb/s.. 64 Kb/s Early 1990s:64 Kb/s.. 2 Mb/s Late 1990s:2 Mb/s.. 155 Mb/s Early 2000s:155 Mb/s.. 10 Gb/s

6 6AC_055_2000 © 2000, Cisco Systems, Inc. Backbone Evolution Late 1980s: 56/64 Kb/s Early 1990s: 1.5/2 Mb/s Mid 1990s: 34 Mb/s, 155 Mb/s Late 1990s: 622 Mb/s, 2,5 Gb/s Early 2000s: 10 Gb/s, 40 Gb/s Late 1980s: 10 Mb/s Early 1990s: 100 Mb/s (FDDI) Mid 1990s: 155 Mb/s (ATM) Late 1990s: nx FE, 155 Mb/s, 622 Mb/s, GE Early 2000s: 10 Gb/s, n x 10 Gb/s WAN Campus

7 7AC_055_2000 © 2000, Cisco Systems, Inc. Transmission Update: 10GE

8 8AC_055_2000 © 2000, Cisco Systems, Inc. Lower Cost and Overhead MAN/WAN IP Transport Alternatives IP ATM Optical B-ISDN IP Optical IP SONET/SDH Optical ATM SONET/SDH IP Optical Multiplexing, Protection and Management at every Layer IP over ATM IP over SDHIP over Optical IP Ethernet Optical IP over Ethernet GE 10GE

9 9AC_055_2000 © 2000, Cisco Systems, Inc. Ethernet Scaling History 1981: Shared 10 Mbit1x 1992: Switched 10 Mbit10x 1995: Switched 100 Mbit100X 1998: Switched 1 Gigabit1000X 200x: Switched 10 Gigabit 10000X

10 10AC_055_2000 © 2000, Cisco Systems, Inc. Moving the Decimal Point: 10 GbE Performance and Scalability 19961997199819992000 1 Gbps 100 Mbps 10 Gbps Ethernet Gigabit Ethernet Fast Ethernet Fast EtherChannel Gigabit EtherChannel STM-64 20012002 10 GbE IEEE 802.3ae Standard LAN applications Metro applications WAN applications

11 11AC_055_2000 © 2000, Cisco Systems, Inc. Why 10 Gigabit Ethernet Aggregates Gigabit Ethernet segments Scales Enterprise and Service Provider LAN backbones Leverages installed base of 250 million Ethernet switch ports Supports all services (packetized voice and video, data) Supports metropolitan and wide area networks Faster and simpler than other alternatives

12 12AC_055_2000 © 2000, Cisco Systems, Inc. IEEE Goals for 10 GbE (Partial List) Preserve 802.3 Ethernet frame format Preserve minimum and maximum frame size of current 802.3 Ethernet Support only full duplex operation Support 10,000 Mbps at MAC interface Define two families of PHYs LAN PHY operating at 10 Gbps Optional WAN PHY operating at a data rate compatible with the payload rate of OC- 192c/SDH VC-4-64c

13 13AC_055_2000 © 2000, Cisco Systems, Inc. IEEE 802.3ae Task Force Milestones 1999200120022000 PARDrafted PARApproved802.3aeFormed FirstDraft WorkingGroupBallot LMSCBallot Standard HSSG= Higher Speed Study Group PAR= project authorization request 802.3ae= the name of the project and the name of the sub-committee of IEEE 802.3 chartered with writing the 10GbE Standard Working group ballot= task force submits complete draft to larger 802.3 committee for technical review and ballot LMSC: LAN/MAN Standards Committee ballot. Any member of the superset of 802 committees may vote and comment on draftHSSGFormed First 10GE deliveries

14 14AC_055_2000 © 2000, Cisco Systems, Inc. 10 Gigabit Ethernet Media Goals 1300 nm Laser CDWM (4x2.5) 1300 nm Laser standard reach Media Type Type 1550 nm Laser extended reach 40-100 km std/dispersion free fiber single mode fiber 2-10 km multimode fiber multimode fiber 300 m 200 m ribbon multimode fiber Max Distance 780 nm VCSEL multichannel

15 15AC_055_2000 © 2000, Cisco Systems, Inc. IEEE Status 802.3ae Meeting 10.-14. Juli 2000 75% Consensus 1550nm Transceiver 40 Km @ SMF 1300nm Transceiver 10 Km @ SMF No Consensus yet Multimode Support 300m mit 62.5µ 160/500 Mhz*Km MM 50µ 2000/500 MHz*Km MM

16 16AC_055_2000 © 2000, Cisco Systems, Inc. Router Architectures

17 17AC_055_2000 © 2000, Cisco Systems, Inc. Components Memory Architecture Interconnect Forwarding Engine Scalability Stability Queueing / QoS

18 18AC_055_2000 © 2000, Cisco Systems, Inc. Basic Design Data are of random sizes Arrival is async, unpredictable, independantly on i/f Data have to be buffered TCP/IP traffic is bursty, but short-term congestion only Router... Inputs Outputs Forwarding Engine Route Processor Buffer Memory Interfaces

19 19AC_055_2000 © 2000, Cisco Systems, Inc. How much buffers ? Rule of Thumb: RTT x BW (Villamizer & Song, High Performance TCP in ANSNET, 1994) STM-16 @ 200 ms: ~ 60 MB buffering capacity

20 20AC_055_2000 © 2000, Cisco Systems, Inc. How to Buffer ? SRAM Fast, Power-hungry, Density 8 Mb -> 16 Mb, Simple Controller Design DRAM / SDRAM Slower, Less Power, Density 64 Mb -> 256 Mb, Complex Controller Design

21 21AC_055_2000 © 2000, Cisco Systems, Inc. Interconnect Switch Fabric / Crossbar Shared Memory Variations

22 22AC_055_2000 © 2000, Cisco Systems, Inc. Switch Fabric / Crossbar Packet forwarding decision done on each linecard Ingress and Egress Buffering on Linecards Possible Problem: Head of Line Blocking Solution: VOQ Line Card 0 Line Card 0 Switch Fabric Switch Fabric Scheduler Line Card 1 Line Card 1 Line Card N Line Card N Line Card 0 Line Card 0 Line Card 1 Line Card 1 Line Card N Line Card N RP Ingress Line CardsEgress Line Cards

23 23AC_055_2000 © 2000, Cisco Systems, Inc. Linecard in Detail Physical Layer (Optics) Physical Layer (Optics) Layer 3 Engine Layer 3 Engine Fabric Interface Fabric Interface RX TX CPU To Fabric From Fabric Switch Fabric Switch Fabric Scheduler HOL Blocking can occur when packet cannot flow off transmit linecard Packet will be buffered on receiving linecard Packet blocks other packets to other linecards Solution: Virtual Output Queues, one per egress linecard

24 24AC_055_2000 © 2000, Cisco Systems, Inc. Receive Line Card Transmit Line Card Group of 8 CoS Queues Per Interface (M-DRR) Input Ports Output Ports Crossbar Switch Fabric W-RED CAR CEF Virtual Output Queues DRR GSR Queuing Architecture

25 25AC_055_2000 © 2000, Cisco Systems, Inc. Shared Memory Architecture Physically Centralized One large memory system, data passing through it Simple memory management High speed memory Simple Linecards Needs SRAM for high speeds Interconnects & Forwarding Engine Interconnects & Forwarding Engine 2.5Gbps Line Cards 1-8 Memory Controller 40 G

26 26AC_055_2000 © 2000, Cisco Systems, Inc. Shared Memory Architecture Distributed Memory distributed over linecards Memory controller treats sum of pieces as shared memory Packet forwarding decision in central engine(s) Difficult to maximize interconnect efficiency Egress line cards simply request packets from shared memory Causes Head of Line (HOL) blocking and high latency, worsening under moderate-to- heavy system load or with multicast traffic Memory Controller & Forwarding Engine(s) Memory Controller & Forwarding Engine(s) Memory System 2.5Gbps Memory System 2.5Gbps Line Cards 1-8

27 27AC_055_2000 © 2000, Cisco Systems, Inc. Switch Fabric vs. Shared Memory Shared Memory requires only half the buffer space HOL Blocking in Shared Memory, especially for Multicast Involvement of distributed shared memory causes more points of failure

28 28AC_055_2000 © 2000, Cisco Systems, Inc. Forwarding Engine Classifying the packet IPv4, IPv6, MPLS,... Packet validity (TTL, length,...) Next Hop Basic Statistics Optional: Policing, Extended Statistics, RPF check (security, Multicast), QoS, Tunnel,... Distributed vs. Central

29 29AC_055_2000 © 2000, Cisco Systems, Inc. Central Forwarding ? IP Longest match Hash vs. TCAM vs. Tree Lookup Tree Lookup requires high number of routing table lookups Need SRAM Danger to run out of SRAM Forwarding speed dependant on depth of routing table

30 30AC_055_2000 © 2000, Cisco Systems, Inc. Distributed Forwarding One copy of forwarding info per linecard Parallel processing without sync or communication between linecards Able to use TCAMs and SDRAMs

31 31AC_055_2000 © 2000, Cisco Systems, Inc. So, its all just speed ?

32 32AC_055_2000 © 2000, Cisco Systems, Inc. So, its just speed ? Services IP Multicast IP QoS Security IPv6 MPLS Manageability Availability Investment protection

33 33AC_055_2000 © 2000, Cisco Systems, Inc. Interdomain Multicast Campus Multicast Multicast Solutions End-to-End Architecture End Stations (hosts-to-routers): IGMP Switches (Layer 2 Optimization): IGMP Snooping Routers (Multicast Forwarding Protocol): PIM Sparse Mode Multicast routing across domains MBGP Multicast Source Discovery MSDP with PIM-SM ISP B Multicast Source Y ISP A Multicast Source X ISP B DR RP DR IGMP PIM-SM CGMP MBGP MSDP ISP A

34 34AC_055_2000 © 2000, Cisco Systems, Inc. Summary IP Routers have evolved during the past years Line rate up to 10 Gb/s Crossbar architectures with distributed forwarding seem to scale better than shared memory architectures Services remain the most decisive factor

35 35AC_055_2000 © 2000, Cisco Systems, Inc. Outlook 10 Gb/s Interfaces supported in 2000 10GE, STM-64/OC-192 High density of 10 Gb/s interfaces soon in a PoP Next step will be STM-256/OC-768 = 40 Gb/s Will these routers be Palm-Size ? Probably not...


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