Cisco Ccnp Certification Bcmsn Exam Tutorial Writing Qos Policy

Cisco Ccnp Certification Bcmsn Exam Tutorial Writing Qos Policy



Cisco CCNP Certification / BCMSN Exam Tutorial: Writing QoS Policy
QoS - Quality of​ Service - is​ a​ huge topic on​ both the​ BCMSN exam and real-world networks .​
QoS is​ so big today that Cisco's created separate specialist certifications that cover nothing but QoS! It can be an​ overwhelming topic at​ first,​ but master the​ fundamentals and you're on​ your way to​ exam and job success.
If you work with QoS at​ any level - and sooner or​ later,​ you will - you've got to​ know how to​ write and apply QoS policies .​
Creating and applying such a​ policy is​ a​ three-step process .​
1. Create a​ QoS class to​ identify the​ traffic that will be affected by the​ policy.
2. Create a​ QoS policy containing the​ actions to​ be taken by traffic identified by the​ class.
3. Apply the​ policy to​ the​ appropriate interfaces.
If the​ phrase identify the​ traffic sounds like it's time to​ write an​ access-list,​ you're right! Writing an​ ACL is​ one of​ two ways to​ classify traffic,​ and is​ the​ more common of​ the​ two .​
Before we​ get to​ the​ less-common method,​ let's take a​ look at​ how to​ use an​ ACL to​ classify traffic.
You can use either a​ standard or​ extended ACL with QoS policies .​
The ACL will be written separately,​ and then called from the​ class map.
SW1(config)#access-list 105 permit tcp any any eq 80
SW1(config)#class-map WEBTRAFFIC
SW1(config-cmap)#match access-group 105
Now that we've identified the​ traffic to​ be affected by the​ policy,​ we​ better get around to​ writing the​ policy! QoS policies are configured with the​ policy-map command,​ and each clause of​ the​ policy will contain an​ action to​ be taken to​ traffic matching that clause .​
SW1(config)#policy-map LIMIT_WEBTRAFFIC_BANDWIDTH
SW1(config-pmap)#class WEBTRAFFIC
SW1(config-pmap-c)#police 5000000 exceed-action drop
SW1(config-pmap-c)#exit
This is​ a​ simple policy,​ but it​ illustrates the​ logic of​ QoS policies .​
The policy map LIMIT_WEBTRAFFIC_BANDWIDTH calls the​ map-class WEBTRAFFIC .​
We already know that all WWW traffic will match that map class,​ so any WWW traffic that exceeds the​ stated bandwidth limitation will be dropped .​
Finally,​ apply the​ policy to​ the​ appropriate interface.
SW1(config-if)#service-policy LIMIT_WEBTRAFFIC_BANDWIDTH in
Getting your CCNP is​ a​ great way to​ boost your career,​ and learning QoS is​ a​ tremendous addition to​ your skill set .​
Like I​ said,​ learn the​ fundamentals,​ don't get overwhelmed by looking at​ QoS as​ a​ whole,​ and you're on​ your way to​ success!




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