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Now you're not expected to know this for the CCMA exam but I'm going to demonstrate an example of quality

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of service on two Cisco routers in this example.

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I've got two routers running in genius three show run interface serial to slash zero shows us the configuration

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these routers simply have IP addresses configured and I have no shut to the interfaces no other configuration

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has been done.

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Show interface several to slash zero shows us the speed of the interface which is using the default

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of one point five four megabits per second so on this interface of the router we can use the command

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auto cores.

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Now notice we do have the discovery option where we can configure the Rada to discover traffic that

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traverses that interface.

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But in this example I'm simply going to enable the interface for VoIP and I'm not going to specify the

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option Trust which means it's not going to trust the markings that it receives from Roorda to now typically

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in the real world you would do that you would trust traffic from one writer to another unless rather

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1 is a service provider and wrote it to as a customer as an example.

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Now here I'm going to use order cause VoIP trust so that you can see the difference between trusting

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and not trusting a neighboring router.

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So rather one doesn't trust it to write it to trusts rather one based on the order cost configuration

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now order quotes creates a large amount of configuration so rather than you manually typing configuration

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it's done for you because write it to trusts rather one it's created a quality of service class map

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that matches DCF so essentially if it to received traffic from write a one marked as E.F. it's going

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to go into this order cause VoIP RTP trust CLOs that's referenced by this policy map the configuration

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that you see here is an example of in QC or the modular quality of service command line interface it

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consists of two main parts.

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We've got class maps and we've got policy maps and policy maps then bound onto interfaces so in this

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example we've got the service policy which references the policy map bound to the serial to slash the

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zero interface so going back to our class maps we've got two class maps one matching DCP E.F. and one

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matching either.

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Notice the match any keyword class selector 3 or IP precedence 3 and assured forwarding Class 3 1 or

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a 3 1 rather tooth trusting the markings that it receives from reader 1.

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So it's looking for traffic that matches E.F. and that class is then matched within this policy map.

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So notice the name or the quoted voice RTP trust is matched here and it's given 70 percent of the interface

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bandwidth.

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When there's congestion.

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So in other words voice traffic match by E.F. will be given a priority bandwidth of 70 percent.

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That's a priority queue.

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This is an example of low latency queuing.

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We've got classes of traffic but we've also got a priority key.

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So this is the priority key in low latency killing of voice will be given 70 percent of the bandwidth

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other traffic.

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So in this case we've got a VoIP control is given 5 percent of the bandwidth notice.

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This matches the class configured over here which is matching C S three and a half 31.

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That's essentially called signalling protocols such as sip H3 3G 3 and skinny.

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In other words those are protocols you use to set up telephone calls so notice what order quizzes done.

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It's allocated 75 percent of the interface bandwidth to voice calls so the actual voice traffic the

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RTP traffic gets 70 percent call signaling gets 5 percent and the remaining traffic is shared using

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fake queuing.

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So this is an example of waited for queuing on the default class default.

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Class is going to match anything not explicitly matched so a low latency queue is actually pretty key.

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Class based weighted fake queuing but that's too much of a mouthful.

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So we call it low latency queuing.

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There's the pretty key.

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Here's an example of a class and this is an example of waited for queuing within a class low latency

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queuing is pretty queuing class based waited for queuing.

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And in this example we approach rising VoIP traffic over other traffic types.

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70 percent of the bandwidth can be taken by voice calls.

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It's a priority queue so it will be serviced first.

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5 percent of the interface bandwidth could be taken by call signalling.

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But this is a guaranteed minimum bandwidth not a priority.

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This is a guaranteed minimum bandwidth of 70 percent of the interface bandwidth.

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But it's a priority queue so voice traffic will be poor terrorized over all other traffic if voice traffic

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is only using 20 percent of the interface bandwidth other traffic can use whatever is not reserved for

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voice.

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So this is a maximum amount of bandwidth that voice can take and voice will be policed at that level.

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But in the worst case scenario other traffic will only get 25 percent of the bandwidth.

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This policy is applied on the serial to slash a zero interface outbound so any traffic leaving the Rada

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will be prior terrorised or cute.

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Based on this configuration.