Cisco Certified Network Associate Day 43
Welcome back everyone, I am Imran
Rafai, your trainer for this entire
series. today we are going to talk about
distance vector versus links state and
this video is going to act like a
precursor to our most sought-after video
which is OSPF and EIGRP. so
we'll be starting OSPF and EIGRP. The next
may be about four or six videos are
going to be the most important of your
entire CCNA... right so they
are going to be the most critical videos
the next four videos or maybe I might
stretch to six videos right
we'll cover OSPF and EIGRP and today
it's going to a very brief video we
would just look at few concepts that you
need to know before we start into OSPF
and EIGRP right so without wasting much
time let's get straight into today's
class and like always before we get into
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imran dot rafai @ nwking dot org
so if you have any query with
regard to this course or anything in
particular regarding a career or IT
please feel free to write to me and I will
try and answer all your queries what are
we going to look at in this video? so we
in our last video we looked at 2.1
so in this video we would be looking at
2.2 which is compare and
contrast distance vector and link-state
routing protocols and also we will look
at 2.3 which is compare and
contrast interior and exterior routing
protocols so these are the two things we
would look into in this video and I
think that is going to be a precursor to
our next maybe six videos like I said
that is going to be our core it's going
to be OSPF
version 2 and version 3. EIGRP for IPv4
amia EIGRP for ipv6 and this is going to
be the core and it is one of the most
requested topic in our entire series
here so without wasting much time let's
get into today's video so two important
topics that I want you to understand and
this is interview questions I have had a
lot of my students come and ask me this
question because this has been asked by
interviews whenever they go for an
interview they've asked him what is
rotting protocol and what's the
difference between routing protocol and
router protocol or double protocol so if
the difference between routing protocol
and order protocols routing protocol is
a protocol used by routers so we looked
at RIP in our I seen the one video and
RIP is a routing protocol so other
routing protocols are a jarppi and OSPF
is is BGP whatever it is all routing
protocol so basically what a lot in
protocol does is it's a way routers talk
to each other right routers talk to each
other and make like they exchange
Network information so takes in network
information and the ultimate objective
is to fill the routing table so routing
table filling by both the devices right
so this is what for a routing protocol
is not in protocol they exchanged at
route information that they have
connected to them or that they learn
from some other source so they share
with each others and ultimate objective
is to fill the routing table and once
you have the routing table they know how
to make routing decision so that's what
a routing protocol is routable
and router attack all is once the rota
makes the decision to fill the routing
table it needs to sell the traffic so
there's some traffic that means to be
sent to that particular network right
they use routed or out table protocols
like ipv4 like for in ipv4 ipv6 right
these are router protocol
to protocol so routed protocol audible
protocols are used to send traffic right
so routing protocol is used to fill the
routing table without a protocol
inaudible protocol like ipv4 and ipv6
are used to send traffic so data is
encapsulated in IP headers right so IP
is a protocol that is used so they
encapsulate data they break the data
into IP packets and thin this in so IP
protocol right ipv4 ipv6 is used by the
routers to send traffic so the
difference we're not team protocol and
router the router protocol is this the
next difference is the discussion that
we need to have is in tt protocol an
exterior gateway protocol now interior
gateway now they say gateway here so
don't get confused ok - basically what
they're trying to say is ami routing
protocol used within an autonomous
system right autonomous system let's say
for instance if it's your company right
your company you have let's say 50 or
routers so this whatever IP protocol
that you use within your company right
this is one autonomous system autonomic
system is something that you call which
is managed by one company or one
organization right so this is autonomous
system so whatever IP protocol that you
use within your company or or autonomous
system that is why it's calling tier so
everything that is used within an
autonomous system is calling teaser gave
your protocol and the protocol that is
used to communicate between two
different autonomous systems that is
called exterior right so this is
interior and the ones that is used
outside the art from a system is called
a next year autumn protocol so basically
this autonomous system also could be
your ISP right your ISP
we would have maybe 200 devices 200 out
isn't within that so that is one
autonomous system and what is used in
between is a nod from a system so what I
intended you two protocols include
protocols that we discuss rip OSPF EIGRP
right
our interior gateway protocols the HTTP
protocol today the only exterior gateway
protocol that's in use is called as bgp
Prada gateway protocol right so this is
a protocol that is used exterior so
exceeding gateway protocol the protocols
used to connect towards from a system
right so that is the difference between
CV give you protocol and exterior
gateway protocol the next two terms that
you need to understand is distance
vector and link state right so these are
the two types of routing protocols for
interior gateway protocols the two types
of interior gateway protocols one is
distance vector right distance vector
and the other is called link state so
let's say for instance we have three
routers right we have three routers and
they connect with each other so let's
assume there is one network 192 168 10.0
/ 24 Network now let's say let's call
this a router a router be and router C
now in the way the trip in I seen d1 we
know that if rip is enabled router
be-because ought to be is connected to
one edge 160 10.0 router be would
advertise this network on this on this
link to router a and also it would
advertise the same network to router C
now Rob you see put it in turn advertise
that to router a so from rod is
perspective let's assume this is f 0 / 0
and this F 0 / 1 right so from a
perspective snob is perspective it is
learning this network 192 168 10.0 from
B and from C if you're using wrap
because it makes use of a metric called
as hop count it would take this because
this is it's saying I have access to
this network with one hop and bit and
see that it has access to
network with one hop see tells a that it
has access to the same network from two
hops so from is perspective from F zero
slash zero it's getting a one hop
distance to this network and why are we
bout to see it is getting the top
distance to this router so obviously a
because it is using rip and rip is a
distance vector routing protocol it
decides on router B so with the
information that we have on the screen
you say that's the right decision to do
because that's the shortest distance but
what if I told you this is a 64 kbps
line whereas this is let's say 100 Mbps
line and this is also a 100 Mbps line
now which what do you think is the
better link do you think the slow 64
kbps line is better or do you think this
100 Mbps line is better
obviously this 100 Mbps line is much
better even though it is 2 hops right so
that even if this information is given
to it that doesn't consider this
information in their routing decisions
it is going to choose the low the least
hop count which is 1 in this case but
the other type of routing protocol is
link-state and OSPF uses link-state
right it is a link-state routing
protocol so what is before do is oils PF
would look at the link state like this
is 64 this is hundred and this is 100
OSPF will decide to go through this
instead right which is a correct thing
to do that's why OSPF is a much much
complicated and much comprehensive
routing protocol compared to rate which
is it is a very basic routing protocol
now both of them have their own
advantages and disadvantages rip like I
said is very basic it's easy to
configure OSPF really complicated you
need to understand a lot of our factors
before we configure that usually is a
cisco proprietary or at least one cisco
proprietary
till very reason
me today it was open standard so eh I'll
be combined the best of both worlds so
it looked at distance vector and it
looked at link state and it made routing
protocol which took into consideration
bandwidth and it took in to consider the
delay right so it took like for delay if
it's longer link it is one we know it's
if it's got more hops obviously there's
going to be more delay if it looks at
the bandwidth so it knows which is a
higher bandwidth link right so it looks
into both if you look at the when you do
a very soon you'll understand what I'm
talking about there is a formula for
which it connects it derives their
metrics so bandwidth of delay is part of
the formula right so that's how it makes
the decision so that's the difference
between distance vector and link state
where distance vector looks at only the
distance in link state looks at only the
link State like the speed and the
bandwidth well eh our Beach is known as
a hybrid routing protocol and it is con
hybrid because it looks at both its
takes a little bit of distance vector
and it takes a little bit of link state
right so hybrid protocol like eh IP does
much better so from a Cisco perspective
ERG Rd is the best route info to call to
use so all the Cisco engineers would
prefer that because if we look at the
next line you will see that it has got a
better believability we will talk about
that in a while
but OSPF is the most used shorting
protocol in the world if it's a non
Cisco environment OSPF is most sought
after because it's an open standards
always been an open standard but here's
our B recently it has gone open standard
so people are starting to use that
because it's a much more advanced
operating a routing protocol so I talked
about believability now normally like in
this case when router a gets to where it
gets information about the same
two different sources it had a formula
through which it makes a decision and
only one of them goes into the routing
table right that's very easy because it
looks at this option it looks at this
option and it knows what to compare and
it makes a decision and one of the entry
goes here
of course OSPF can do load balancing if
it's a similar cost so if both of them
have exactly the same cost you can do
load balancing and don't worry about all
that we will come back into load
balancing a little bit of OSPF in our
next video but for this video understand
that load balancing is possible but the
load balancing for a bit it makes a
decision whatever that decision it makes
a decision and one of the network goes
into the routing table right it's easy
to make a decision but consider this now
you have plotted a route of B let's call
it a and this is B and router C and this
is a company like it's your company
right now let's assume you your company
acquired another company this happens
merge and acquisition keep happening in
in the real world so let's assume you
quired
or your company acquired another company
which has router a1 b1 and c1 and then
you have ABC
let's assume this old company of yours
so this is company 1 and this is your
quiet company and let's assume you have
been using ERP and your new company that
you have acquired uses OSPF now changing
something that's happening some of this
being like it's not annotates are
possible to change this company over to
eigrp or move your company for me a job
you to OSPF but it's a lot of
administrative headache right and and
and then the whole process of change
management then it's a big
administrative headache if the company
is big it's huge if it's small company
yes you can do
there's none of you don't really have to
do that you can do something called as
free distribution right so you could
take routes from here grp andrey dispute
to OSPF and take rods from OSPF and
redistribute it to be happy this is
possible how do we do that once a router
in your network would do both right so
you do EIGRP and OSPF right so let's
assume this router you be router know to
be put to eeh we're bein OSPF so it
thinks it has a routing table in the
routing table you will have routes that
is denoted by learned by EIGRP then you
and have some rods learnt by OSPF right
so you have both the networks so if you
have unique networks then there is no
problem you know that like for instance
in this company you have some network
that is there only in this company and
there's some network that's there in
this company so whatever there in the
company on the right would be only on
OSPF whatever networks that you have on
your own network atonia but for some
reason let's assume this some type of
interconnection now you have a
particular network that is learnt by
both OSPF also has a link to that
network right there some network and
EIGRP also has linked to that network
now both of them both of them yogya GRP
the routes routing table also turns okay
there is this sort of table I've learned
through the HRP now LSBF also says I
have learnt this route through my
routing protocol now you can't compare
this apple on ology there is no way that
I can compare between two different
routing protocol without having a way to
have a believer be disabled so that's
why we have something called as the
admin distance now adding distance
it's if it's a directly connected route
right if if this road you're talking
about this network then it's a connected
network it will have an ad of zero
that's the most believable right so if
you have somebody like for instance
about this route if B is directly
connected that that and if a is saying
that I have access to this particular
route right whatever this route he is
sailing he also knows about bid through
C right obviously we will say thank you
so much for giving me that information
but he is directly connected to me and I
believe that more than anybody else oh I
don't need your information right that's
believability so connected is zero
that's the most believable then you have
starting route if your administrator has
statically configured around that's the
second most believable then ERG RP is 90
it's better than OSPF which is 110 which
is better than rip which is 120 right
so if HR P must be both half and I both
advertise in the same network the router
will believe we are GRP because ERG RP
is cos 90 which is more believable so
that is going to be used most of the
time right so this is what admin
distances admin distance is a way to
have believability when you are using
multiple routing protocols right so like
I said this is a brief video it's more
like a precursor just wanted to get you
all up to date or up to speed with some
of the topics some of the topics that is
part of our exam topics on CNN like you
know that we are following i Cindy - so
these are two examples that was there
2.2 and 2.3 so we have covered that and
next is 2.4 we will get straight into
your most sought after topic in our
entire
not icnd2 icnd1 I'm talking about entire
CCNA to program to be running here this
is the more sought after we have had
multiple requests we will have a square
as ro SP we do is erp video you know
what that is the video that's gonna come
next week right
so stay tuned and we will see you right
back bye bye