Cisco CCNP / BSCI Exam Tutorial: Introduction To Policy Routing

Policy Routing is one of the major topics on your BSCI exam, and you will see very little policy routing happening in today& 39;s production networks. But what is a policy routing?
Policy based routing, commonly referred to as a political " Routing & quot; is the use of routes to find out how the package will take to reach their final destination. As you progress through your CCNP studies and move to CCIE (Cisco or on the quality of services, certification), you will find that traffic can be marked " & quot; on the routing policy, in order to provide different levels of service for different classes of traffic. (This is done by marking traffic and traffic facilities of different classes in different queues in the router, which allows the administrator to provide some traffic higher priority for the transfer.)
There some basic routing policy rules you should know:
Policy not routing & quot ; t influence the appointment package, but does not affect the path taken to get there.
Policy routing can send traffic through the IP address of the source and destination IP addresses (using the extended ACL).
Policy routing can be configured on the interface level, or globally.
Applying routing policy on the interface affects only packages arriving at that interface:
R2 (config) int s0
R2 (configuration-if) ip route-map policy CHANGE NEXT HOP
Applying policy applies worldwide route map for the packets generated on the router , and not all packets from all interfaces.
Whether you work in the routing policy on the interface level at the packages created locally, or both, has always run the command show ip policy to make sure you have the right routes on the proper interfaces.
R2 show ip route map policy
Interface
local CHANGE NEXT HOP
Serial0 CHANGE NEXT HOP
And here in a big rule to remember ....
If package does not match any of the specific criteria on the route map, or not in accordance with the line, which is obviously denies the statement, the data are sent to the routing process, and will be handled as usual. If you do not want to route packages that do not meet any criteria, the route map, a set of command should be used to send those packets to the null0 interface. This set of commands is to be the final set of commands in the route map.
There four opportunities for the incoming packet, when the route maps in use. The following example illustrates all of them.
R2 (config) 29 access list allow 20.1.1.1
R2 (config) 30 access list allow 20.2.2.2
R2 (config) 31 access list allow 20.3.3.3
R2 (config) access list 32 allow 20.4.4.4
R2 (config) route map permission EXAMPLE 10
R2 (configuration-route-map) ip address of 29 matches
R2 (configuration-route-map) ip next set-hop 40.1.1.1
R2 (configuration -- route-map) route map permission EXAMPLE 20
R2 (configuration-route-map) ip address of 30 matches
Assuming route map has been used for router ethernet0 interface, the package comes with 20.1.1.1 will meet on the first line on the map of the route, and its next-hop IP address set to 40.1.1.1.
A package comes with 20.2.2.2 will conform to the following statement permit (number 20). Since there is no action listed, the package will be returned to the routing engine undergo normal routing procedures. All traffic, which do not meet these two addresses will also be sent as a rule - no action would be taken on the route map.
Perhaps we want to specifically block traffic coming from 20.3.3.3 or 20.4.4.4. We can use several statements coincided with a single route map " and packages that match these two addresses sent to the bucket a little bit - null0 interface.
R2 (config) route map permission EXAMPLE 30
R2 (configuration-route-map) ip address of 31 matches
R2 (configuration-route-map) ip address of 32 matches
R2 (configuration-route-map) set?

as Prepend-way line for BGP AS-path attribute
automatic tag automatically calculate the value of TAG
comm list BGP community set list (deleted)
community BGP community attribute
dampening Set BGP routing valve moistening
default Set Defaults information
extcommunity BGP Attribute extended community Result
interface
ip IP interface specific information
level Where import preferences BGP routing
local local preferences
metric Metric path attribute importance to the destination routing protocol
metric type metrics for the type of destination routing protocol BGP
origin origin code tags
tag importance to the destination routing protocol
weight BGP routing tables weight

R2 (configuration-route-map) install interface null0
Any movement, the relevant ACL is 31 or 32 will be sent to null0, resulting in his discarded to the router. Any movement that does not match any of the route map applications will be returned to the routing engine for normal processing.
Knowing routing policies, and how to apply it is necessary skills to pass the exam BSCI, earning your CCNP, and becoming increasingly valuable in today& 39;s job market. Get some hands-on practice in CCNA / CCNP home lab or rack rental go to the study of theory, and you will be writing and application routing policies in a short time. ramal jaymie



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