Whenever you're making ready to cross the BSCI exam on the best way to the coveted Cisco CCNP certification, you will be shortly overwhelmed by the sheer quantity of BGP and OSPF knowledge you must reveal a mastery of. One set of particulars that some BSCI and CCNP candidates underestimate are the differences between the OSPF router types.
An OSPF Inner router has one rule - it must have all its interfaces in a single area. It does not mean that area must be Space 0.
An OSPF Backbone router is a router with no less than a single space within the OSPF backbone space, Space 0. A router can be both an Internal and Backbone router if all its interfaces are in Space 0.
An Area Border Router has at least one interface in Area 0 and another interface in a non-spine area. ABRs are also one among two router types that can carry out OSPF route summarization. (To promote an abstract route from one OSPF space to a different, use the realm vary command on the ABR.)
Finally, an ASBR is an OSPF router that's performing route redistribution by injecting routes from another source into the OSPF domain. This is the opposite OSPF router kind that may carry out route summarization; to summarize routes being redistributed into OSPF, use the summary-tackle command on the ASBR.
There are several instructions you need to use to find out the router types in a given OSPF area. The command "present ip ospf" will show fairly a bit of information relating to the native router, and this consists of whether that router is performing as an ABR or ASBR. To see the routes to the ABRs and ASBRs from the local router, run "show ip ospf border-routers".
Making ready to move the BSCI examination and earn your Cisco CCNP? Route summarization is simply one of many many skills you will must grasp in order to earn your CCNP. Whether or not it's RIP model 2, OSPF, or EIGRP, the BSCI exam will demand you could flawlessly configure route summarization.
Route summarization isn't just necessary for the BSCI exam. It is a priceless skill to have in the real world as well. Accurately summarizing routes can result in smaller routing tables that are still in a position to route packets accurately - what I wish to name "concise and complete" routing tables.
The primary skill you've got to have in order to work with route summarization is binary math more particularly, you need to be capable to take multiple routes and give you each a summary route and mask to advertise to downstream routers. Given the networks 100.16.0.zero /16, 100.17.0.zero /sixteen, 100.18.0.0 /sixteen, and 100.19.0.zero /16, may you quickly come up with both the abstract address and masks? All it's essential to do is break the four network numbers down into binary strings. We all know the last two octets will all convert to the binary string 00000000, so in this article we'll solely illustrate how to convert the primary and second octet from decimal to binary.
100 16 = 01100100 00010000
100 17 = 01100100 00010001
one hundred 18 = 01100100 00010010
100 19 = 01100100 00010011
To provide you with the summary route, simply work from left to proper and draw a line the place the 4 networks no longer have a bit in common. For these four networks, that time comes between the 14th and fifteenth bits. This leaves us with this string: 01100100 000100xx. All it is advisable do is convert that string back to decimal, which gives us a hundred for the primary octet and 16 for the second. (The two x values are bits on the suitable side of the road, which aren't used in calculating the summary route.) Since we know that zero is the value for the last octets, the resulting abstract network number is 100.16.0.0.
However we're not accomplished! We now need to come up with the abstract mask to promote together with the summary route. To arrive on the summary route, write out a mask in binary with a "1" for each bit to the left of the road we drew previously, and a "0" for every bit to the right. That gives us the next string:
11111111 11111100 00000000 00000000
Changing that to dotted decimal, we arrive at the abstract masks 255.252.0.0. The right summary network and masks to advertise are 100.16.0.0 252.0.0.0.
For the BSCI exam, emphasis is placed on figuring out learn how to promote these abstract routes in RIPv2, EIGRP, and OSPF. For RIP v2 and EIGRP, route summarization occurs on the interface level - it isn't configured beneath the protocol. On the interface that ought to promote the summary route, use the command "ip abstract-address". Listed below are examples of how the above summary route could be configured on ethernet0 in each RIPv2 and EIGRP.
R1(config-if)ip summary-tackle rip 100.16.0.0 255.252.0.zero
R1(config-if)ip abstract-handle eigrp one hundred 100.16.0.zero 255.252.0.0
The main difference between the two is that the EIGRP command should specify the AS number - that is what the "one hundred" is in the course of the EIGRP command. Since RIPv2 doesn't use AS numbers, there's no further value wanted within the configuration.
For OSPF, the instructions differ. If you happen to're configuring inter-space route summarization, use the "space vary" command. The number following "space" is the realm containing the routes being summarized, not the world receiving the summary.
R1(config)router ospf 1
R1(config-router)area 1 vary 100.16.0.0 255.252.0.0
If you're summarizing routes which are being redistributed into OSPF, use the abstract-tackle command beneath the OSPF routing course of on the ASBR.
R1(config)router ospf 1
R1(config-router)abstract-handle 100.16.0.zero 255.252.0.zero
I communicate from experience after I tell you that apply makes perfect on the BSCI exam, particularly with binary and summarization questions. The beauty of these questions is that there are no grey areas with these questions - you either know how you can do it otherwise you don't. And with practice and one eye on element, you can master these expertise, pass the examination, and change into a CCNP. Here is to your success on these powerful Cisco certification exams!
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