Cisco Ccnp Bcmsn Exam Tutorial Switches Qos And Ciscos Networking Model

Cisco Ccnp Bcmsn Exam Tutorial Switches Qos And Ciscos Networking Model

Cisco CCNP / BCMSN Exam Tutorial: Switches, QoS, and​ Cisco's Networking Model
QoS is​ a​ big topic on your BCMSN and​ CCNP exams, and​ for​ good reason .​
as​ more and​ more traffic flows through today's networks, accurately applying QoS to​ both your routers and​ switches becomes more important.
Note the​ phrase accurately applying .​
You must have a​ plan in​ place before you start configuring QoS on your switches, and​ to​ create such a​ plan you should use Cisco's Three-layer Hierarchical Model.
This model breaks switches down into three main groups - Access, Distribution, and​ Core .​
You're familiar with these groups from your CCNA studies, and​ now you've got to​ apply this knowledge.
The QoS workload should be borne by the​ Access and​ Distribution layers, because the​ Core layer switches need to​ be left alone as​ much as​ possible to​ their primary purpose - switching!
Traffic should generally be classified and​ marked at​ the​ Access layer .​
This allows traffic to​ be assigned the​ desired QoS values and​ carry that value throughout the​ network .​

If you choose to​ change CoS-DSCP mappings, this will generally be done at​ the​ Distribution layer .​
Since distribution layer switches will be receiving frames and​ packets with QoS values from the​ access layer switches, the​ appropriate trust and​ no trust statements should be configured on the​ appropriate distribution layer switches.
Any traffic received by core switches should already be classified and​ marked as​ needed .​
the​ key with core switches is​ to​ use a​ simple queuing setup to​ keep the​ switching process fast .​
Fast, fast, fast!
Real-world note - Low Latency Queuing (LLQ) is​ an​ excellent choice for​ core switches .​
the​ name says it​ all - low latency! the​ configuration of​ LLQ is​ not a​ BCMSN topic, but a​ quick search on the​ term low latency queuing will quickly bring up several Cisco LLQ configuration documents.
Knowing the​ three layers of​ Cisco's networking model and​ the​ basic QoS operation and​ commands is​ vital to​ passing the​ CCNP exams, but even more importantly, you've got to​ apply this knowledge carefully and​ accurately to​ make QoS work for​ you in​ today's production networks.

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