Showing posts from January, 2013

QoS Part II: Congestion Management, Traffic Policing and Shaping

When we are talking about the QoS Congestion Management and Avoidance, the three most important terms are: queuing, dropping and scheduling. Queuing places the packets into the different software queues based on the QoS labels. After the traffic is classified and marked with QoS labels, you can assign the traffic into a certain number different queues based on the QoS labels.

WRED (Weighted Random Early Detection) is the only RED method used by Cisco to drop the last packets in the certain queues. Threshold is a number of packets in a queue that when reached the packets start being dropped. 

The number of QUEUES and THRESHOLDS will depend on the Switch characteristics. Different configurations will be applied accordingly. Refer to the list of devices for details:

Dedicate the BW to each of the queues. Set the VOICE traffic as the single strict priority queue to guarantee a minimum delay, and the WRR scheduling method for the remaining queues to guarantee the bandwidth.

You can check the …

Cisco WAAS Part II: Configuration

Cisco WAAS Part II: Configuration

There are a few things we need to know before we configure our traffic to utilize the WAAS: -          - The protocol WAAS uses is called WCCP (Web Cache Coordination Protocol) -          - 61 and 62 are the Service Identifier Numbers of WCCP protocol (61 for the origin traffic and 62 for the response traffic) -
Create the Access-List with your WAEs (in this case there are 2): ip access-list standard Cisco_WAES  permit  permit Create 2 Access Lists, one for the traffic originated in your own network towards the destination network (where the other end of WAAS service is), and the second one for the response traffic from the other side of WAAS service.
ip access-list extended OUR_SIDE2OTHER_SIDE  deny   tcp host any  permit tcp  permit tcp
ip access-list extended OTHER_SIDE2OUR_SIDE  deny   tcp any host  permit tcp 172.1…

Cisco WAAS Part I: WAN Link Optimization: How does WAAS work?

Cisco WAAS Part I:  WAN Link Optimization
“Cisco WAAS is a software and hardware-integrated, cloud-ready WAN optimization and application acceleration solution. WAAS appliances offer outstanding deployment scalability and design flexibility while WAAS software delivers best-in-class application acceleration for the enterprise network.”
Many companies actually offer the WAN Optimization solutions. I´m not getting into details of why I think that for example Riverbed offers better and more complete solution (at a much higher cost though). I´m a Cisco guy, so I´ll stick to Cisco technologies and tell you about all the advantages Cisco WAAS (Wide Area Application Services) offers you.
WAAS (Wide Area Applications Services) is the name of the technology (software related). WAE (Wide Area Engine) is the name given to the appliances on which WAAS operates (hardware related)
We sure went a long way since we measured the BW by the baud. Now the LANs are a pretty optimized environment, ap…

QoS Part I: Classification and Marking

QoS Part I: Classification and Marking

Quality of Service (QoS) is the ability to provide different levels of performance for individual applications and services that run over the networks.Different application attributes such as constant vs. burst bandwidth consumption, jitter, perceived latency, error rate, availability and admission control can be controlled by the proper implementation and deployment of QoS. The need for QoS has become increasingly necessary, especially within the backbone network where the real time applications like VoIP and Cisco TelePresence needs to be prioritized.QoS has become crucial for the everyday business needs due to the ever changing traffic load on the network from Internet browsing, streaming media, file transfers, data replication etc. The critical applications should take advantage of QoS and be prioritized, in order to get more preference over non-critical applications.

This is how the switch treats frames by default after the QoS is enabled: -A fr…