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The answer to this trouble is dependent upon the sort of site traffic distinctions you would like to produce, also the edition of IOS you're operating inside of your routers.

There will have to be a little something that defines the various different types of page views you want to prioritize. In general, the more simple the distinctions are in making, the better. It is because every one of the assessments consider router resources and introduce processing delays. The most prevalent guidelines for distinguishing among visitors varieties make use of the packet's input interface and hassle-free IP header particulars such as TCP port numbers. The following examples demonstrate learn how to set an IP Precedence price of quick (2) for all FTP management visitors that arrives via the serial0/0 interface, and an IP Precedence of priority (1) for all FTP information website traffic. This distinction is feasible given that FTP handle targeted traffic usages TCP port 21, and FTP information employs port 20.

The brand new solution for configuring this takes advantage of class maps. Cisco very first introduced this function in IOS Edition twelve.0(5)T. This process first defines a class-map that specifies how the router will establish this sort of visitors. It then defines a policy-map that truly makes the modifications for the packet's TOS industry:

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 before IOS versions, where exactly class-maps had been not around, you have got to use policy-based routing to change the TOS area in a packet. Making use of this coverage into the interface tells the router make use of this coverage to test 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#

Ahead of you may tag a packet for particular treatment method, you've got to own a particularly crystal clear strategy of what different types of website traffic really want particular therapy, coupled with precisely what sort of specific therapy they will might need. In the example, now we have made a decision to give a unique priority to FTP site visitors acquired on a specific serial interface. We demonstrate the best way to do that applying both equally the aged and new configuration methods.
This may show up to become a rather synthetic instance. Soon after all, why would you treatment about tagging inbound site visitors that you simply have presently received from a low-speed interface? Definitely, among the list of most crucial principles for applying QoS within a network is always that make sure you continuously tag the packet as early as is possible, ideally with the edges of your network. Then, as it passes throughout the network, each router only needs to examine the tag, and does not should do any increased classification. In this instance, we'd ensure which the FTP targeted traffic returning from the other gestion is tagged from the 1st router that receives it. And so the outbound site visitors has presently been tagged, and it's a waste of router resources to reclassify the outbound packets.

A lot of organizations honestly get this idea of marking on the edges a particular step even more, and remark each and every acquired packet. This may help to make certain that end users are not requesting unique QoS privileges that they are not allowed to obtain. But, you need to be cautious of this simply because it might frequently disrupt respectable markings. As an example, a real-time software might use RSVP to reserve bandwidth with the network. It happens to be imperative that the packets for this software hold the applicable Expedited Forwarding (EF) DSCP marking or even the network may not deal with them thoroughly. Regardless, additionally you never want to allow other non-real-time programs from this exact same resource have the same EF priority degree. So, for everybody who is heading to configure your routers to remark all incoming packets on the edges, make sure you comprehend what incoming markings are legitimate.

In that case, the routers are working DLSw to bridge SNA page views by an IP network. So the routers themselves truly develop the IP packets. This creates an additional challenge due to the fact there may be no incoming interface. Making sure that recipe usages community policy-based routing. The actual fact the router produces the packets also provides it a very important advantage considering that it doesn't have to contemplate any DLSw packets which may just come about to pass through.

The benefits of the more recent class-map system aren't apparent in this particular example, but one of the many primary tremendous merits seems if you need to make use of the more current DSCP tagging scheme. Since the older policy-based routing system doesn't right help DSCP, you will have to pretend it by setting both the IP Precedence plus the TOS separately 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 may even be useful afterwards in this particular chapter once we mention class-based weighted reasonable queuing and class-based targeted visitors shaping.
It is very important to notice that in the course of this whole illustration, we've only place a wonderful price to the packet's TOS or DSCP industry. This, by itself, does not affect how the packet is forwarded via the network. To carry out that, you must guarantee that as each router while in the network forwards these marked packets, the interface queues will react appropriately to this important information.

Ultimately, we should be aware that though this recipe shows two helpful strategies of marking packets, employing Dedicated Access Price (Vehicle) benefits. Car or truck tends for being a whole lot more effective on greater velocity interfaces.