1. Chassis Architecture Brandon Wagner Office of Information Technology
Infrastructure Design Solutions

2. Who Am I? BS, Information Technology
Work for BYU OIT - 5 years (2 part-time, 3 full-time)
Primary Responsibilities:
Cisco NAC / Wireless
Packetshaping
Packet Analysis
Data Center Design
New Construction Design
Secondary Responsibilities:
Firewalls
Routing/Switching
QoS
Network Security
A Cisco guy (for Ekstrom)

3. What do you know?

4. Lecture Series October 5th October 7th October 12th October 14th
Chassis Architecture
October 7th
Chassis Demo & Convergence/Virtualization
October 12th
Routing Protocols
Evolution of BYU Campus Routing
October 14th
MPLS
Review

5. Learning Outcomes Understand the need for a chassis style switch.
Components of a Chassis switch.
Two types of backplane connectivity.
Two methods of forwarding traffic within a chassis.

6. Scenarios
A sysadmin has three clusters of 48 servers in a data center. They need low latency, high bandwidth connectivity between them. How do you do it?
A service provider is building out their core infrastructure. They need gigabit Ethernet ports, Optical carrier ports, and T1 ports. They need all of them to be able to talk to each other. How do you do it?

7. The Chassis Switch
Chassis - Frame of switch, provides slots for line cards and supervisors, fan tray, power supplies
Backplane – Connects all modules together.
Supervisor - Central CPU for switch
Line Cards - Provide ports for edge or feed connections
Power Supplies – Provide power for line cards, supervisors
Cisco 6509 Chassis
Brocade FastIron SX

8. Why the Chassis? Flexibility Bandwidth Port Density
Service modules – firewalls, wireless controllers, NAMs
Bandwidth
Inter-switch bandwidth. Greater than 100Mb or 1Gb. Ports aren’t used for up-links.
Port Density
A 13 slot chassis can support up to 528 gigabit Ethernet ports.
Centralized Intelligence and Management

9. Chassis Basic Chassis Fan Tray Cost: $2,000 - $7,000
35 – 70 CFM per slot
Pulls air instead of pushing air out.
Cost: $2,000 - $7,000

10. Backplane Shared Bus Switch Fabric
Provides shared bandwidth to all cards.
One connection at a time
Integrated into Chassis
Ex: Cisco 6500 – 32Gbps shared
Switch Fabric
Dedicated bandwidth between slots/cards.
Full Duplex
Standalone line card or integrated into Supervisor
Ex: Cisco 6500 – 16 or 40 Gbps

11. Supervisor MFSC – Multilayer Switch Feature Card Switch Fabric
RP – Route Processor
SP – Switch Processor
Switch Fabric
Provides 16 or 40Gbps
400 Mpps
PFC – Policy Feature Card
MAC Table
Routing/Forwarding Table
ACL/QoS
Management Panel
Cost: $20,000 to $60,000 each

12. Line Cards Various ports of Wire speed vs shared
10/100/1000 Ethernet
Gigabit Fiber Ethernet
10 Gigabit Ethernet
DSx, OCx, T1, T3
Wire speed vs shared
ASIC – Application Specific Integrated Circuit
Centralized vs Distributive Forwarding
Cost: $4,000 – 45,000

13. Power Supplies Output ranges Provides power to: Cost: $1,000 – 8,000
950W to 8700W per supply
Provides power to:
Supervisor
Line cards (functionality)
Line cards (PoE)
Fan tray
Cost: $1,000 – 8,000

14. Centralized Forwarding
Forwarding process:
Packet header (not data payload) is sent over the bus
Supervisor examines packet and determines forwarding decision
Supervisor sends decision over bus
Line card then sends full payload over fabric to destination ASIC
Central because all forwarding decisions are centralized in the supervisor.

15. Distributive Forwarding
Requires line card to have a DFC
Forwarding Process:
Routing/Forwarding config is pushed to DFC on line card.
When packet enters linecard, a decision is made locally.
Data is forwarded over fabic.
No Bus interaction
Distributive because all forwarding decisions are distributed among each line card.

16. Case Study Fabric Utilization Methods in a Cisco 6500
Classic
Centralized forwarding
All traffic traverses the shared bus.
CEF256 (2x8 x 8 x 2)
Bus and Fabric (8Gbps) connection.
dCEF256
Distributed forwarding
Fabric (8Gbps) connection only.
CEF720 (2x20 x 9 x 2)
Bus and Fabric (20Gbps) connection.
dCEF720
Fabric (20Gbps) connection only.
dCEF256
CEF256
dCEF720
CEF720

17. Chassis Design at the Edge
Backplane’s are now being used in Edge Switches.
Stacking Cables daisy chain switches together
Example: Cisco 3750
Provides 32 Gbps shared bus.
New 3750-E Series provides 64 Gbps bus.

18. Pro’s and Con’s Pro’s Con’s Others?
Able to manage hundreds of ports via one management interface.
Very fast backplane for local switching
Doesn’t require using physical ports for switch to switch connectivity.
Con’s
Expensive. Price per port higher for initial deployment.
Greater outage experienced when there is a failure.
Others?

19. Questions?

20. Chassis Around Campus TNRB Building Router JKB Building Router
ITB Building Router