CCIE Voice Training, Environment the DSCP or TOS Area

The answer to this challenge varies according to the kind of site traffic distinctions you wish to create, likewise the version of IOS you could be running inside your routers. CCIE Voice Training

There should be anything that defines the different sorts of customers that you need to prioritize. Generally, the more simple the distinctions are to create, the better. It is because all the tests just take router assets and introduce processing delays. The commonest rules for distinguishing between page views varieties make use of the packet's input interface and straightforward IP header specifics this sort of as TCP port figures. The next examples demonstrate the best way to set an IP Precedence value of fast (2) for all FTP command page views that arrives through the serial0/0 interface, and an IP Precedence of priority (1) for all FTP info site visitors. This distinction is feasible seeing that FTP regulate site visitors utilizes TCP port 21, and FTP knowledge utilizes port twenty.

The newest way for configuring this takes advantage of class maps. Cisco initially released this feature in IOS Version twelve.0(5)T. This process first defines a class-map that specifies how the router will recognize this type of potential customers. It then defines a policy-map that truly makes the modifications to the packet's TOS discipline:

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 variations, wherever class-maps ended up not readily available, you will have to make use of policy-based routing to change the TOS industry within a packet. Applying this policy into the interface tells the router to use 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#

Previously you can easlily tag a packet for unique remedy, you have to get a particularly obvious notion of what kinds of customers ought exceptional therapy, combined with precisely what kind of unique remedy they may absolutely need. Around the instance, we now have decided to give a particular concern to FTP customers obtained on a distinct serial interface. We present the best ways to do this making use of both the old and new configuration solutions.
This might appear for being a considerably synthetic illustration. After all, why would you care about tagging inbound traffic you have presently acquired from a low-speed interface? Realistically, among the list of most crucial concepts for applying QoS inside a network is you really should constantly tag the packet as early as is possible, ideally with the edges belonging to the network. Then, as it passes throughout the network, every router only must take a look at the tag, and doesn't should do any even more classification. In this case, we would guarantee the FTP customers returning from the other intendance is tagged through the initially router that receives it. So the outbound site visitors has presently been tagged, and it is a waste of router sources to reclassify the outbound packets.

Numerous organizations basically get this concept of marking with the edges an individual action additionally, and remark each individual received packet. This allows to make sure that users aren't requesting amazing QoS privileges which they are not authorized to have. Even so, you ought to be cautious of this because it will probably now and then disrupt respectable markings. Such as, a real-time application would possibly use RSVP to reserve bandwidth with the network. It is important that the packets for this application possess the best suited Expedited Forwarding (EF) DSCP marking or the network may not manage them accurately. However, additionally you do not desire to allow other non-real-time programs from this similar supply have the exact same EF priority degree. So, for anybody who is heading to configure your routers to remark all incoming packets on the edges, be sure that you realize what incoming markings are legitimate.

In that scenario, the routers are managing DLSw to bridge SNA site visitors through an IP network. And so the routers by themselves in fact design the IP packets. This produces a further challenge as there may be no incoming interface. In order that recipe makes use of neighborhood policy-based routing. The very fact which the router makes the packets also gives it a significant benefit due to the fact it doesn't have to contemplate any DLSw packets which may just take place to pass through.

The benefits within the more recent class-map solution are not noticeable on this instance, but among the list of number one enormous strengths appears if you need to make use of the more contemporary DSCP tagging scheme. Because the more mature policy-based routing methodology isn't going to specifically help DSCP, you've gotten to pretend it by environment the two the IP Precedence in addition to 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 also be practical later on in this particular chapter when we talk about class-based weighted fair queuing and class-based website traffic shaping.
It will be important to notice that all the way through this complete instance, we've only place a particular price to the packet's TOS or DSCP subject. This, by by itself, does not affect how the packet is forwarded as a result of the network. To complete that, you have got to be certain that as just about every router during the network forwards these marked packets, the interface queues will react appropriately to this content.

Last but not least, we must always observe that though this recipe displays two handy methods of marking packets, employing Committed Access Rate (Motor vehicle) features. Automobile tends for being a little more successful on larger speed interfaces.