The solution to this concern is dependent upon the type of targeted traffic distinctions you desire to make, likewise the model of IOS you will be running as part of your routers. CCIE Voice Training

There will have to be some thing that defines the different different types of page views you want to prioritize. In most cases, the simpler the distinctions are to produce, the better. It is because every one of the tests get router sources and introduce processing delays. The most typical policies for distinguishing involving targeted visitors variations utilize the packet's input interface and rather simple IP header details these kinds of as TCP port figures. The next examples show tips to set an IP Precedence value of fast (two) for all FTP command potential customers that arrives because of the serial0/0 interface, and an IP Precedence of priority (1) for all FTP data targeted visitors. This distinction is feasible seeing that FTP management site visitors takes advantage of TCP port 21, and FTP info makes use of port twenty.

The newest method for configuring this usages course maps. Cisco very first launched this attribute in IOS Version 12.0(5)T. This method foremost defines a class-map that specifies how the router will establish this sort of targeted visitors. It then defines a policy-map that actually helps make the changes towards the packet's TOS field:

Router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#access-list 101 permit any eq ftp any
Router(config)#access-list 101 permit any any eq ftp
Router(config)#access-list 102 permit any eq ftp-data any
Router(config)#access-list 102 permit any any eq ftp-data
Router(config)#class-map match-all ser00-ftpcontrol
Router(config-cmap)#description branch ftp control traffic
Router(config-cmap)#match input-interface serial0/0
Router(config-cmap)#match access-group 101
Router(config-cmap)#exit
Router(config)#class-map match-all ser00-ftpdata
Router(config-cmap)#description branch ftp data traffic
Router(config-cmap)#match input-interface serial0/0
Router(config-cmap)#match access-group 102
Router(config-cmap)#exit
Router(config)#policy-map serialftppolicy
Router(config-pmap)#description branch ftp traffic policy
Router(config-pmap)#class ser00-ftpcontrol
Router(config-pmap-c)#set ip precedence immediate
Router(config-pmap-c)#exit
Router(config-pmap)#class ser00-ftpdata
Router(config-pmap-c)#set ip precedence priority
Router(config-pmap-c)#exit
Router(config-pmap)#exit
Router(config)#interface serial0/0
Router(config-if)#ip route-cache policy
Router(config-if)#service-policy input serialftppolicy
Router(config-if)#exit
Router(config)#end
Router#

For previously IOS versions, where by class-maps happen to be not around, you've got to implement policy-based routing to change the TOS subject within a packet. Making use of this coverage on the interface tells the router to employ this coverage to check all incoming packets on this interface and rewrite those that match the route map:Router#configure terminal

Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#access-list 101 permit any eq ftp any
Router(config)#access-list 101 permit any any eq ftp
Router(config)#access-list 102 permit any eq ftp-data any
Router(config)#access-list 102 permit any any eq ftp-data
Router(config)#route-map serialftp-rtmap permit 10
Router(config-route-map)#match ip address 101
Router(config-route-map)#set ip precedence immediate
Router(config-route-map)#exit
Router(config)#route-map serialftp-rtmap permit 20
Router(config-route-map)#match ip address 102
Router(config-route-map)#set ip precedence priority
Router(config-route-map)#exit
Router(config)#interface serial0/0
Router(config-if)#ip policy route-map serialftp-rtmap
Router(config-if)#ip route-cache policy
Router(config-if)#exit
Router(config)#end
Router#

Well before you can easlily tag a packet for particular treatment, you might have to obtain an especially distinct strategy of what styles of targeted visitors absolutely need special cure, plus specifically what kind of extraordinary therapy they are going to have to have. With the example, we've got chose to give a distinctive priority to FTP visitors obtained on the specified serial interface. We exhibit tips to try this using both equally the old and new configuration procedures.
This will look for being a relatively synthetic illustration. Upon all, why would you care about tagging inbound customers you have by now received from a low-speed interface? Realistically, one of several most significant principles for employing QoS within a network is that often you ought to generally tag the packet as early as is possible, ideally for the edges on the network. Then, since it passes with the network, each and every router only needs to evaluate the tag, and isn't going to have to do any additional classification. In this instance, we would ensure the FTP page views returning during the other intendance is tagged with the to begin with router that receives it. So the outbound website traffic has definitely been tagged, and it's a waste of router assets to reclassify the outbound packets.

Countless organizations definitely consider this concept of marking for the edges an individual step further, and remark every acquired packet. This aids to ensure that users are not requesting amazing QoS privileges which they are not permitted to have. Having said that, you need to be thorough of this due to the fact that it can often times disrupt authentic markings. To illustrate, a real-time software would possibly use RSVP to order bandwidth in the network. It's crucial that the packets for this application hold the best suited Expedited Forwarding (EF) DSCP marking or perhaps the network might not cope with them properly. In spite of this, you also don't desire to let other non-real-time apps from this similar supply have the same exact EF priority amount. So, for everybody who is going to configure your routers to remark all incoming packets at the edges, make sure that you figure out what incoming markings are respectable.

In that scenario, the routers are running DLSw to bridge SNA customers through an IP network. Therefore the routers on their own in fact develop the IP packets. This results in an extra problem due to the fact there's no incoming interface. To make sure that recipe usages native policy-based routing. The actual fact which the router results in the packets also presents it a very important edge due to the fact it doesn't have to contemplate any DLSw packets that might just transpire to go through.

The advantages within the newer class-map process are not evident during this illustration, but one of the many primary huge features seems if you'd like to implement the more modern day DSCP tagging scheme. Since the older policy-based routing methodology would not directly assistance DSCP, you may have to pretend it by environment both equally the IP Precedence plus the TOS individually as follows.

Router(config)#route-map serialftp-rtmap permit 10
Router(config-route-map)#match ip address 115
Router(config-route-map)#set ip precedence immediate
Router(config-route-map)#set ip tos max-throughput

In this case, the packet will wind up with an IP Precedence value of immediate, or 2 (010 in binary), and TOS of max-throughput, or 4 (0100 in binary).

Doing the same thing with the class-map method is much more direct:

Router(config)#policy-map serialftppolicy
Router(config-pmap)#class serialftpclass
Router(config-pmap-c)#set ip dscp af21

Class-maps can even be invaluable later on within this chapter after we mention class-based weighted truthful queuing and class-based visitors shaping.
It is important to note that all the way through this whole instance, we now have only put a exceptional value into the packet's TOS or DSCP area. This, by itself, will not affect how the packet is forwarded via the network. To accomplish that, it's essential to ensure that as just about every router inside the network forwards these marked packets, the interface queues will react appropriately to this data.

At last, we should note that as this recipe demonstrates two handy approaches of marking packets, using Committed Access Pace (Car) features. Car or truck tends to become added productive on increased speed interfaces.

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