OSPF is a major topic on both the CCNA and CCNP exams, and it's also the topic that requires the most attention to detail. Where dynamic routing protocols such as RIP and IGRP have only one router type, a look at a Cisco routing table shows several different OSPF route types.
Laptop Battery R1#show ip route
Occasionally, during your CCNA and CCNP studies, you'll run into a term that just doesn't quite make sense to you. (Okay, more than occasionally!) One such term is "reverse telnet". As a Cisco certification candidate, you know that telnet is simply a protocol that allows you to remotely connect to a networking device such as a router or switch. But what is "reverse telnet", CCNP home lab setup
Thinkpad Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
In this tutorial, we'll take a look at the difference between two of these route types, E1 and E2.
Route redistribution is the process of taking routes learned via one routing protocol and injecting those routes into another routing domain. (Static and connected routes can also be redistributed.) When a router running OSPF takes routes learned by another routing protocol and makes them available to the other OSPF-enabled routers it's communicating with, that router becomes an Autonomous System Border Router (ASBR).
Let's work with an example where R1 is running both OSPF and RIP. R4 is in the same OSPF domain as R1, and we want R4 to learn the routes that R1 is learning via RIP. This means we have to perform route redistribution on the ASBR. The routes that are being redistributed from RIP into OSPF will appear as E2 routes on R4:
R4#show ip route ospf
Passing the BCSI exam and earning your CCNP certification requires you to know OSPF stub areas inside and out. Stub areas, total stub areas, stub stub areas ... and pretty soon your head is swimming. Then when you hear that EIGRP offers stub routing, your first reaction may be unprintable! But while EIGRP stub routing is effective in the right situation, it's not as complex as OSPF stub routing. Let's take a look at basic EIGRP stub routing.
Microsoft O E2 5.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet0
821, the first exam in Cisco' exam Cisco Certified Network Associate (CCNA) certification track. Understand networking for the small or home office market, prepare for the exam, and acquire the skills you need with this comprehensive guide. Inside you'
Laptop Computers 6.0.0.0/32 is subnetted, 1 subnets
Errata Description Author Information Cisco Certified Network Associate Study Guide, 6th Edition ( 04700110082) -The Cisco Certified Network Associate (CCNA) tier certification and by far its most popular. depth coverage of every exam objectives, plus updates that reflect technology developments over the past years. It addition, it offers expanded coverage on key topics reflected in the new version of the exam. Finally, the enhanced CD contains over an hour of useful video and audio files, as well as the Sybex Test Engine, Flahscards, and entire book in PDF format.
Laptop Computer O E2 6.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet0
level certification. or user requirements. They should also be able to develop and test a prototype network that validates the design to the user's satisfaction. Candidates must possess a valid CCNA or CCDA certification prior to taking these exams. For rmation on the CCDP program, visit the related page on the Cisco Web site.
Desktop Computer 172.12.0.0/16 is variably subnetted, 2 subnets, 2 masks
Notebooks O E2 172.12.21.0/30 [110/20] via 172.34.34.3, 00:33:32,
Ethernet0
Lenovo O E2 7.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet0
Hard Drive 15.0.0.0/24 is subnetted, 1 subnets
Travelstar O E2 15.1.1.0 [110/20] via 172.34.34.3, 00:33:32, Ethernet0
Gateway E2 is the default route type for routes learned via redistribution. The key with E2 routes is that the cost of these routes reflects only the cost of the path from the ASBR to the final destination; the cost of the path from R4 to R1 is not reflected in this cost. (Remember that OSPF's metric for a path is referred to as "cost".)
In this example, we want the cost of the routes to reflect the entire path, not just the path between the ASBR and the destination network. To do so, the routes must be redistributed into OSPF as E1 routes on the ASBR, as shown here.
R1#conf t
Laptop Parts Enter configuration commands, one per line. End with CNTL/Z.
Software R1(config)#router ospf 1
Hard Drives R1(config-router)#redistribute rip subnets metric-type 1
Electronics Now on R4, the routes appear as E1 routes and have a larger metric, since the entire path cost is now reflected in the routing table.
O E1 5.1.1.1 [110/94] via 172.34.34.3, 00:33:21, Ethernet0
Canon 6.0.0.0/32 is subnetted, 1 subnets
Desktop Pc O E1 6.1.1.1 [110/100] via 172.34.34.3, 00:33:21, Ethernet0
Desktop Computers 172.12.0.0/16 is variably subnetted, 2 subnets, 2 masks
Think Pad O E1 172.12.21.0/30 [110/94] via 172.34.34.3, 00:33:32, Ethernet0
Repair O E1 7.1.1.1 [110/94] via 172.34.34.3, 00:33:21, Ethernet0
Data Recovery 15.0.0.0/24 is subnetted, 1 subnets
Cisco O E1 15.1.1.0 [110/94] via 172.34.34.3, 00:33:32, Ethernet0
Keyboard
Monitor Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, Ultimate CCNP Study Packages, and CCNA CBT video training. Pass the CCNA exam ,BSCI exam , and BCMSN exam with Chris Bryant, CCIE #12933!
For a copy of his FREE "How To Pass The CCNA" or "How To Pass The CCNP" ebook and receive a FREE CCNA and CCNP question every day, just visit the website and claim your free copies!
