1. 1 Router Design Bruce Davie bsd@cisco.com with help from Hari Balakrishnan & Nick McKeown

2. 2 Router Design 2006 © 2006, Bruce Davie Routers Cisco CRS-1 LinksysJuniper T-series

3. 3 Router Design 2006 © 2006, Bruce Davie Cisco’s moment of fame

4. 4 Router Design 2006 © 2006, Bruce Davie Basic Router Function: Forwarding Lookup IP Address Update Header Header Processing DataHdrDataHdr Forwarding Table Forwarding Table IP AddressNext Hop Queue Packet Buffer Memory Buffer Memory

5. 5 Router Design 2006 © 2006, Bruce Davie d(technology)/dt for networks Moore’s Law 2x / 18 months DRAM Access Time 1.1x / 18months Highest Link Capacity 2x / 7 months Aggregate Internet Traffic 2x / 12 months 1 10 100 1,000 10,000 100,000 1,000,000 19801983198619891992199519982001 Normalized Growth since 1980 Speed of light 0x / 18 months! Bits/s per dollar 2x / 79 months (crude estimate) # Internet hosts 2x / 13.3 months

6. 6 Router Design 2006 © 2006, Bruce Davie “Simple” Crossbar-Based Output-Queued Switch Lookup IP Address Update Header Header Processing Address Table Address Table Lookup IP Address Update Header Header Processing Address Table Address Table Lookup IP Address Update Header Header Processing Address Table Address Table Buffer Manager Buffer Memory Buffer Memory Buffer Manager Buffer Memory Buffer Memory Buffer Manager Buffer Memory Buffer Memory

7. 7 Router Design 2006 © 2006, Bruce Davie Router linecard Physical Layer Framing & Maintenance Packet Processing Buffer Mgmt & Scheduling Buffer Mgmt & Scheduling Buffer & State Memory Buffer & State Memory OC192c linecard  30M gates  2.5Gbits of memory  2-300W  1m 2  $25k cost, $100k price. Lookup Tables Optics Scheduler 40-55% of power in chip-to-chip serial links

8. 8 Router Design 2006 © 2006, Bruce Davie Packet processing gets harder time Instructions per arriving byte What we’d like: (more features) QoS / overload protection, Multicast, Security, VPN, stats, congestion control, IPv_n, MPLS, VLANs, layer-N classification,… What will happen

9. 9 Router Design 2006 © 2006, Bruce Davie Crossbar Linecards Switch Linecards Trend: Multi-rack routers Reduces power density

10. 10 Router Design 2006 © 2006, Bruce Davie Self-routing Fabric (Banyan)