The solution to this main problem depends on the kind of targeted traffic distinctions you want to produce, at the same time the version of IOS you will be running in your routers. CCIE Voice Training

There ought to be something that defines the different sorts of page views that you just want to prioritize. Typically, the simpler the distinctions are to produce, the better. It's because each of the checks take router assets and introduce processing delays. The most prevalent principles for distinguishing between site traffic styles make use of the packet's input interface and simple and easy IP header answers these as TCP port figures. The subsequent examples present proven methods to set an IP Precedence worth of instant (two) for all FTP management site traffic that arrives as a result of the serial0/0 interface, and an IP Precedence of concern (one) for all FTP information customers. This distinction is feasible simply because FTP regulate site visitors uses TCP port 21, and FTP knowledge works by using port 20.

The brand new technique for configuring this uses class maps. Cisco to start with released this attribute in IOS Version twelve.0(5)T. This method initial defines a class-map that specifies how the router will recognize this sort of customers. It then defines a policy-map that truly helps make the alterations for the packet's TOS subject:

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 earlier IOS variations, where class-maps have been not available, you've gotten to employ policy-based routing to change the TOS discipline inside of a packet. Making use of this coverage with the interface tells the router make use of this policy to test all incoming packets on this interface and rewrite the ones 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#

Earlier than one can tag a packet for extraordinary procedure, you have got to possess a particularly obvious strategy of what different types of site visitors ought particular treatment method, along with exactly what kind of wonderful treatment method they're going to will want. Around the case in point, we have chose to give a exclusive concern to FTP customers obtained on a precise serial interface. We display techniques to try this implementing both the old and new configuration approaches.
This will likely seem to be a rather artificial example. Right after all, why would you treatment about tagging inbound customers that you have currently received from a low-speed interface? In fact, one of several most significant ideas for implementing QoS in a network is the fact that you have to nearly always tag the packet as early as you possibly can, ideally for the edges in the network. Then, as it passes with the network, each and every router only must look at the tag, and would not should do any supplemental classification. In this case, we might guarantee which the FTP site visitors returning within the other route is tagged by number one router that receives it. And so the outbound traffic has definitely been tagged, and it is a waste of router assets to reclassify the outbound packets.

Loads of organizations in fact take this concept of marking for the edges one particular action additional, and remark each acquired packet. This aids to guarantee that people aren't requesting unique QoS privileges which they aren't allowed to have. Though, you need to be cautious of this due to the fact that it may possibly frequently disrupt authentic markings. Such as, a real-time application will probably use RSVP to reserve bandwidth from the network. It is critical the packets for this software have the best suited Expedited Forwarding (EF) DSCP marking or even the network might not take care of them appropriately. But, you also never hope to permit other non-real-time apps from this same exact supply hold the very same EF priority amount. So, for anybody who is heading to configure your routers to remark all incoming packets with the edges, make certain you recognize what incoming markings are legitimate.

In that scenario, the routers are managing DLSw to bridge SNA site traffic by an IP network. And so the routers on their own truly establish the IP packets. This generates an extra problem simply because there exists no incoming interface. To ensure that recipe usages neighborhood policy-based routing. The fact the router makes the packets also gives it a significant benefit for the reason that it does not have to look at any DLSw packets that may just transpire to pass through.

The advantages within the more recent class-map process are not clear in this illustration, but among the list of to start with great benefits seems if you need to make use of the more contemporary DSCP tagging scheme. Since the older policy-based routing approach does not immediately support DSCP, you will have to faux it by environment both the IP Precedence along with the TOS independently 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 will likely be advantageous later on during this chapter when we discuss class-based weighted reasonable queuing and class-based potential customers shaping.
It is crucial to notice that in the course of this whole example, we've only put a special value in to the packet's TOS or DSCP area. This, by itself, will not have an impact on how the packet is forwarded because of the network. To complete that, you have to be sure that as just about every router from the network forwards these marked packets, the interface queues will react appropriately to this important information.

Eventually, we should always note that even while this recipe shows two invaluable procedures of marking packets, making use of Dedicated Access Fee (Vehicle) capabilities. Car or truck tends to be a bit more reliable on increased speed interfaces.