The solution to this trouble relies on the kind of traffic distinctions you wish to build, also the edition of IOS you're jogging inside your routers.

There needs to be some thing that defines the different sorts of site visitors that you need to prioritize. Generally speaking, the more simple the distinctions are for making, the better. This is because each of the exams just take router assets and introduce processing delays. The most prevalent policies for distinguishing amongst targeted traffic variations make use of the packet's input interface and relatively easy IP header facts such as TCP port figures. The following examples show tips to set an IP Precedence price of fast (two) for all FTP regulate page views that arrives by the serial0/0 interface, and an IP Precedence of concern (1) for all FTP data targeted traffic. This distinction is feasible since FTP manage targeted traffic makes use of TCP port 21, and FTP data uses port twenty.

The newest solution for configuring this makes use of course maps. Cisco number one introduced this element in IOS Model twelve.0(five)T. This process initially defines a class-map that specifies how the router will detect this sort of visitors. It then defines a policy-map that actually helps make the alterations to your 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 previously IOS variations, where class-maps had been not around, you may have to make use of policy-based routing to alter the TOS industry inside of a packet. Making use of this policy for the interface tells the router to implement this coverage 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#

Previous to you can still tag a packet for wonderful treatment method, you've gotten to get an extremely clear concept of what styles of customers have to have extraordinary therapy, and even exactly what sort of amazing cure they're going to have to have. In the instance, we've got chose to give a particular concern to FTP site visitors received on a specified serial interface. We clearly show how one can try this making use of equally the outdated and new configuration methods.
This may appear to get a considerably synthetic case in point. As a result of all, why would you care about tagging inbound site traffic that you simply have previously acquired from a low-speed interface? Definitely, one of the most critical concepts for implementing QoS in the network is the fact that it is important to forever tag the packet as early as you can, preferably on the edges in the network. Then, as it passes throughout the network, each and every router only has to consider the tag, and does not ought to do any added classification. In cases like this, we might be certain which the FTP website traffic returning from the other administration is tagged by very first router that receives it. So the outbound customers has definitely been tagged, and it is a waste of router sources to reclassify the outbound packets.

Numerous organizations in actual fact consider this idea of marking in the edges 1 stage even more, and remark each individual obtained packet. This can help to make sure that users aren't requesting special QoS privileges which they aren't authorized to have. Having said that, you should be watchful of this because it can generally disrupt legitimate markings. To illustrate, a real-time application may very well use RSVP to order bandwidth throughout the network. It's essential that the packets for this application possess the appropriate Expedited Forwarding (EF) DSCP marking or perhaps the network may not deal with them properly. But nevertheless, you also never would like to let other non-real-time apps from this identical resource hold the exact EF priority degree. So, should you be heading to configure your routers to remark all incoming packets for the edges, be sure that you fully grasp what incoming markings are genuine.

In that situation, the routers are operating DLSw to bridge SNA targeted traffic because of an IP network. And so the routers themselves in actual fact build the IP packets. This creates an additional problem considering there may be no incoming interface. To ensure that recipe works by using area policy-based routing. The fact which the router creates the packets also gives it a crucial gain simply because it does not have to look at any DLSw packets that might just occur to pass through.

The advantages of your newer class-map procedure are not evident within this case in point, but among the many to start with gigantic pros seems if you need to work with the more present day DSCP tagging scheme. As the more mature policy-based routing procedure isn't going to directly assistance DSCP, you've got to faux it by setting both the IP Precedence as well as 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 also be helpful afterwards on this chapter once we talk about class-based weighted fair queuing and class-based potential customers shaping.
It will be important to notice that during this entire instance, now we have only put a distinctive value to the packet's TOS or DSCP field. This, by itself, will not have an effect on how the packet is forwarded by way of the network. To undertake that, you must ensure that as just about every router during the network forwards these marked packets, the interface queues will react appropriately to this specifics.

Last but not least, we should always observe that as this recipe shows two invaluable ideas of marking packets, making use of Committed Access Price (Car or truck) capabilities. Motor vehicle tends for being a bit more efficient on bigger velocity interfaces.

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