 |
Cisco CCNP Certification: Introduction To BGP |
 |
|
Cisco certification candidates are introduced to BGP at the
CCNP level, but the reaction to its introduction always reminds
me of something I see often as the CCNA level.
Whenever I teach distance-vector protocols in my Ultimate
CCNA Boot Camp or Fast Track classes, I make sure my students
understand the many rules of distance-vector routing thoroughly.
After that, we move on to OSPF and link-state routing.
And what do I tell my students before we move on to OSPF
and link-state? "Take all that great stuff you just learned
about distance-vector routing and put it aside, because none
of it applies here!"
That's about the time I get astonished looks and a few things
thrown at me. :)
What's this got to do with BGP? Well, when you start studying
BGP, you have to put a lot of preconceptions aside. It sounds
like just another routing protocol, like RIP or OSPF, but
it's not.
So... before we start studying BGP and looking at some of
its many features, let's take a look at what BGP is and what
it's not.
What BGP Does And Who Uses It
If you're in a position where you're used to seeing or working
with routing protocols such as EIGRP and OSPF, you're probably
now working with BGP. BGP is not a protocol you're going to
configure at the office LAN. BGP is used to connect autonomous
systems, which are very large "collections" of networks.
(Those of you who have studied IGRP and EIGRP are familiar
with the concepts of an AS.)
As opposed to routing protocols such as EIGRP and OSPF, BGP
is an exterior routing protocol. BGP is not used to find a
specific network instead, it's used to find the AS where that
given network can be found.
A good way to look at it is that networks are contained in
Autonomous Systems BGP helps you find the AS where a given
network is found. Routing protocols such as OSPF and EIGRP
take it from there.
BGP Terminology
You'll be happy to know that BGP has a terminology all its
own. Well, you might not be happy about it, but it does! I'm
not going to throw a bunch of terms at you right now, since
these terms are better introduced to you when you can see
what they do. Having said that, here are a couple of basic
BGP terms that will help you make the transition from IGPs
to BGP.
aggregation - This is just the BGP term for summarization.
You're familiar with route summarization from your CCNA studies,
and if not, it's time for a review from my Ultimate CCNA Study
Guide. I told you you'd be using those skills for a long time!
IGP - Interior Gateway Protocol. These are routing protocols
that run within an Autonomous System, such as OSPF and EIGRP.
EGP - Exterior Gateway Protocol. Remember from your CCNA
studies that EIGRP routes are indicated by the letter "D"
in your routing table? Ever wonder why? EGP, that's why. Run
show ip route and take a look at the routing table key. EGP
was BGP's predecessor, and is still in the routing table.
EGP was there before EIGRP, so that's why "E" in
the routing table doesn't indicate an EIGRP route.
We'll be adding to this list a great deal in the next few
weeks.
Now that you've got a grasp on the differences between BGP
and the IGPs you've been working with up to this point, it's
time to start looking at some basic BGP concepts and configurations.
Look for Part II of this BGP tutorial over the next few days!
About the Author:
Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage,
home of free CCNP and CCNA tutorials, The Ultimate CCNA Study
Package, and Ultimate CCNP Study Packages. For a FREE copy
of his latest e-books, “How To Pass The CCNA” and
“How To Pass The CCNP”, just visit the website!
You can also get FREE CCNA and CCNP exam questions every day!
Pass the CCNP exam with The Bryant Advantage!
|
|
|
|
Relevant Resources |
|
|
|
|
|
Need Cisco Hardware for your Cert? |
|
|
| Call 813.852.6400 now for more information to find the best router or switch to best help you with your certification exam. Having "real" hands-on experience is extremely beneficial not just for testing, but also ensures you are actually familiar with the device you are working on.
|
|
|
|
|
Cisco Routers |
|
|
|
|
|
Cisco Switches |
|
|
|
|
|
