Exam Essentials

Remember the different IOS traffic-management control features. Access lists, proxy services, compression, encryption, and queuing are IOS traffic-management control features. Access lists are the primary control method for traffic flow. Proxy services allow Cisco routers to respond on behalf of network services. Compression can save bandwidth at the expense of the router CPU. Queuing is required when priority traffic must get through.

Understand the types of access lists. Access lists offer many different types for traffic control. Their primary use is often security.

Know the different types of compression available with the Cisco IOS. Header, payload, and link are all types of compression. Header compression only affects the IP header, whereas payload compression compresses only the data. Link compression affects both the IP header and the data payload.

Understand the different queuing methods. FIFO, weighted fair, priority, and custom queuing are all methods of traffic queuing. FIFO does not help with time-sensitive traffic, because there is no priority placed on the data. Weighted fair queuing provides equal amounts of bandwidth to each conversation but places a higher priority on low-volume traffic. Priority queuing works on a packet-by-packet basis, and custom queuing allows for the customization of traffic types.

Understand the traffic-shaping techniques used to meet QoS requirements. RSVP allows for bandwidth reservation and traffic shaping. RSVP allows the network designer to reserve up to 75 percent of the available bandwidth for time-sensitive traffic and works best when applied to serial WAN links.