The solution to this downside will depend on the type of potential customers distinctions you want to make, in addition the model of IOS that you are operating on your routers.

There should be anything that defines the different styles of customers that you just need to prioritize. Normally, the less complicated the distinctions are to build, the better. This is because every one of the assessments take router assets and introduce processing delays. The most prevalent guidelines for distinguishing between customers types use the packet's input interface and easy to understand IP header important information these as TCP port quantities. The next examples exhibit how you can set an IP Precedence price of quick (two) for all FTP regulate traffic that arrives by using the serial0/0 interface, and an IP Precedence of concern (1) for all FTP info customers. This distinction is feasible considering the fact that FTP management targeted visitors takes advantage of TCP port 21, and FTP information utilizes port 20.

The brand new procedure for configuring this utilizes course maps. Cisco number one launched this attribute in IOS Version 12.0(5)T. This process primary defines a class-map that specifies how the router will recognize this type of targeted visitors. It then defines a policy-map that truly helps make the variations 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 earlier IOS versions, wherever class-maps were not offered, you've got to employ policy-based routing to change the TOS area in a very packet. Making use of this coverage towards the interface tells the router to use 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 one can tag a packet for exceptional therapy, you will have to own an especially crystal clear idea of what varieties of targeted visitors really want amazing procedure, and even precisely what kind of extraordinary therapy they'll really want. During the instance, we have now made a decision to give a amazing priority to FTP site traffic obtained on a special serial interface. We display the way to do this by using each the previous and new configuration techniques.
This may show up to get a relatively artificial example. Following all, why would you treatment about tagging inbound targeted traffic you have by now obtained from a low-speed interface? Basically, on the list of most critical rules for utilizing QoS in a network is the fact that be certain to frequently tag the packet as early as possible, preferably at the edges in the network. Then, since it passes in the network, just about every router only must consider the tag, and isn't going to will want to do any further classification. In cases like this, we might make certain which the FTP traffic returning while in the other path is tagged from the first router that receives it. So the outbound site visitors has presently been tagged, and this is a waste of router sources to reclassify the outbound packets.

A variety of organizations ultimately get this concept of marking for the edges an individual stage further, and remark each and every obtained packet. This can help to guarantee that customers aren't requesting distinctive QoS privileges that they are not allowed to have. At the same time, you need to be cautious of this seeing that it could now and then disrupt legit markings. To illustrate, a real-time application could use RSVP to order bandwidth in the network. It is actually necessary which the packets for this application hold the ideal Expedited Forwarding (EF) DSCP marking or even the network might not deal with them effectively. At the same time, additionally you never aspire to let other non-real-time programs from this exact source possess the identical EF priority stage. So, for anyone who is heading to configure your routers to remark all incoming packets for the edges, confirm you appreciate what incoming markings are genuine.

In that scenario, the routers are operating DLSw to bridge SNA visitors because of an IP network. So the routers themselves truly set up the IP packets. This makes an extra problem mainly because there's no incoming interface. To ensure recipe works by using lieu policy-based routing. The very fact the router makes the packets also provides it a vital advantage simply because it does not have to look at any DLSw packets that might just occur to pass through.

The benefits within the newer class-map technique aren't obvious on this case in point, but one of several initial enormous benefits appears if you would like to make use of the greater fashionable DSCP tagging scheme. Because the mature policy-based routing solution would not straight assistance DSCP, you've to pretend it by environment both equally the IP Precedence also, 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 may even be handy later in this chapter when we discuss class-based weighted reasonable queuing and class-based customers shaping.
It can be crucial to note that during this entire illustration, we've only place a special price into the packet's TOS or DSCP industry. This, by alone, would not influence how the packet is forwarded by the network. To complete that, it's essential to guarantee that as each router with the network forwards these marked packets, the interface queues will react appropriately to this content.

At long last, we should notice that when this recipe shows two helpful tactics of marking packets, employing Dedicated Entry Fee (Motor vehicle) attributes. Car tends to get added effective on higher pace interfaces.