The solution to this predicament will depend on the sort of targeted traffic distinctions you prefer to build, likewise the version of IOS you're working within your routers. CCIE Voice Training

There have to be one thing that defines the various sorts of potential customers that you need to prioritize. Usually, the easier the distinctions are to produce, the better. This is because every one of the exams get router sources and introduce processing delays. The most prevalent guidelines for distinguishing between targeted traffic sorts make use of the packet's input interface and painless IP header information such as TCP port numbers. The following examples show tips to set an IP Precedence worth of rapid (two) for all FTP handle visitors that arrives through the serial0/0 interface, and an IP Precedence of concern (one) for all FTP data targeted traffic. This distinction is feasible on the grounds that FTP handle targeted traffic makes use of TCP port 21, and FTP info utilizes port twenty.

The newest process for configuring this employs course maps. Cisco initially launched this element in IOS Version twelve.0(5)T. This method to begin with defines a class-map that specifies how the router will detect this sort of website traffic. It then defines a policy-map that really makes the changes with 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 before IOS versions, exactly where class-maps ended up not obtainable, you've gotten to implement policy-based routing to alter the TOS industry inside a packet. Applying this policy to the interface tells the router to use this policy 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#

Previous to you can easily tag a packet for distinctive therapy, you have to own an extremely very clear plan of what kinds of site traffic would need exceptional treatment, combined with precisely what sort of exclusive treatment they're going to ought. During the instance, we've made a decision to give a wonderful priority to FTP website traffic obtained on the unique serial interface. We clearly show proven methods to try this implementing both the outdated and new configuration techniques.
This will show up for being a considerably artificial illustration. Subsequent to all, why would you care about tagging inbound page views which you have presently received from a low-speed interface? Basically, one of several most significant rules for applying QoS in the network is the fact it is important to constantly tag the packet as early as is possible, preferably on the edges on the network. Then, because it passes through the network, every single router only must consider the tag, and isn't going to will need to do any additional classification. In cases like this, we'd make certain which the FTP page views returning in the other course is tagged by the 1st router that receives it. Therefore the outbound site visitors has by now been tagged, and it's a waste of router assets to reclassify the outbound packets.

Countless organizations ultimately just take this idea of marking in the edges one action even further, and remark every received packet. This allows to be sure that customers are not requesting particular QoS privileges they aren't authorized to possess. Even so, you should be mindful of this considering that it can now and then disrupt legitimate markings. Such as, a real-time application could possibly use RSVP to order bandwidth in the network. It's essential which the packets for this application possess the acceptable Expedited Forwarding (EF) DSCP marking or perhaps the network might not cope with them adequately. Even so, you also never like to permit other non-real-time programs from this identical resource have the identical EF concern stage. So, if you're heading to configure your routers to remark all incoming packets with the edges, make certain you appreciate what incoming markings are reputable.

In that case, the routers are running DLSw to bridge SNA site traffic by way of an IP network. Therefore the routers by themselves in actual fact set up the IP packets. This generates a further challenge for the reason that there may be no incoming interface. Making sure that recipe takes advantage of community policy-based routing. The actual fact the router produces the packets also provides it a crucial edge due to the fact that it doesn't have to think about any DLSw packets that may just happen to go through.

The advantages with the more recent class-map method are not clear on this example, but one of several initial big rewards seems if you want make use of the more present day DSCP tagging scheme. Because the older policy-based routing way won't directly assistance DSCP, you've gotten to fake 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 even be helpful later on in this particular chapter when we discuss class-based weighted honest queuing and class-based site traffic shaping.
It is necessary to notice that all over this complete illustration, we now have only set a amazing worth into the packet's TOS or DSCP discipline. This, by by itself, won't have an impact on how the packet is forwarded by using the network. To do that, you ought to be sure that as each and every router during the network forwards these marked packets, the interface queues will react appropriately to this detail.

Lastly, we must always note that though this recipe displays two beneficial options of marking packets, making use of Committed Access Rate (Car or truck) attributes. Automotive tends to be considerably more efficient on increased velocity interfaces.