CHASSIS ARCHITECTUREBrandon Wagner

Office of Information Technology

Infrastructure Design Solutions

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)

What do you know?

Lecture Series• October 5th

• Chassis Architecture

• October 7th • Chassis Demo & Convergence/Virtualization

• October 12th

• Routing Protocols• Evolution of BYU Campus Routing

• October 14th

• MPLS• Review

• Email: brandon_wagner@byu.edu

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.

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?

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

Why the Chassis?• Flexibility

• 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

Chassis• Basic Chassis

• Fan Tray• 35 – 70 CFM per slot• Pulls air instead of pushing

air out.

• Cost: $2,000 - $7,000

Backplane

• Shared Bus

• 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

Supervisor• MFSC – Multilayer Switch

Feature Card• 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

Line Cards• Various ports of

• 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

Power Supplies• Output ranges

• 950W to 8700W per supply

• Provides power to:• Supervisor• Line cards (functionality)• Line cards (PoE)• Fan tray

• Cost: $1,000 – 8,000

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.

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.

Case StudyFabric Utilization Methods in a Cisco 6500

• Classic• Centralized forwarding• All traffic traverses the shared

bus.

• CEF256 (2x8 x 8 x 2)• Centralized forwarding• Bus and Fabric (8Gbps)

connection.

• dCEF256• Distributed forwarding• Fabric (8Gbps) connection only.

• CEF720 (2x20 x 9 x 2)• Centralized forwarding• Bus and Fabric (20Gbps)

connection.

• dCEF720• Distributed forwarding• Fabric (20Gbps) connection only.

CEF256

CEF720 dCEF720

dCEF256

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.

Pro’s and Con’s• Pro’s

• 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?

Questions?

Chassis Around Campus

TNRB Building Router JKB Building Router ITB Building Router