In this video we're going to discuss Oh SPF designated rowdies or bras and backup designated Rodders
or BDO.
This is one of multiple videos and in this first video let's see if we can answer some basic questions
in this topology.
How many designated riders are there.
In other words how many dealers will be elected in this topology.
Second question how many backup designated routers or BDO cars are they in this topology
and thirdly how many D or others or druthers are they in this topology.
So can you answer how many dealers how many BD hours how many days are others are there in this topology
notice that brought one rider to write a three and Rod a four or connected to a layer to switch.
There is no configuration on the switch route a force connected to ratify via serial link and route
of five is connected to wrote a six via an Ethernet link.
How many dealers how many BDO hours how many days or others.
So let's configure the topology and find out in this topology of only configured IP addresses.
I haven't configured always SPF so not a one show IP protocols or SPF is not configured
Let's paste a basic o SPF configuration onto the rudder we've enabled or SPF on all interfaces on the
router show IP or SPF interface.
Brief SPF is enabled on gigabit 00 current state is weight that's the link here gigabit 00 is the link
to the switch
after a while the state should change but the rudder waits to see if other route are configured on the
same segment in this example the Rada has become the designated Rada that would make sense because there
are no other routers configured on the layer to switch and brought it to show IP protocols SPF is not
currently running paste the OSP SPF config in neighbor relationship has been established and the state
has gone to full show IPO SPF neighbor we can see that Rider 2 has formed a relationship with Rod a
1 rather 1 is the D.R. a full relationship exists to that broader show IPO SPF interface brief shows
us that the local Rada is a backup a designated Rada What about Rada 3 show IP protocols or SPF is not
currently enabled on the strata salt paste in the configuration the Rada has formed to neighbor relationships
one with a one one with Robert to sort of show IP 0 SPF interface brief who SPF is enabled on the local
gigabit 00 interface the router is a D or other.
In other words SPF is running on this interface gigabit 00 router 3 has become a D or other or draw
the show IP who is P.F. Neighbor to Neighbor relationships exist one to right of one who's the D.R.
another 2 rod a 2 which is the BTR notice full relationship which means that rod so exchanged between
these routers so Rada 3 will synchronize its 0 SPF database with a 1 and Rod a 2.
Okay so Rod 4 show IP protocols who Piff is not enabled on this Rhonda
the output is different here because this road is running version twelve four of IAW with these other
riders are running fifteen point six.
They are Iowa's v riders whereas this rider is a C 30 725 rider so IP protocol shows no writing protocols
all enable or SPF on all interfaces on this rider show IP 0 SPF interface brief this Rada is acting
as a D or other on the fast ethernet interface and it has a point to point connection on the serial
interface we can see that a relationship was formed to route a two and wrote a one so show IP SPF neighbor
it only forms a full relationship with Russia one and wrote it two.
In other words the D.R. and the PDR it does not form a full relationship was wrote a three on route
a three we should see something similar previously rudder three had a full relationship with rudder
one and rudder too it still has that but it has a two way relationship or half formed relationship with
Russia for so on this Ethernet segment we have one the D.R. will ADR and BDO are be elected on this
link so let's test that three out of five show IP protocols no protocols are running let's enable SPF
show IP 0 SPF interface brief 0 SPF is enabled on the serial interface as well as the first Ethernet
interface of router 5.
So it's running here and here currently it's set to wait on first Ethernet it's point to point on the
serial notice stall point to point on the serial show IP who SPF neighbor this Rada has a full relationship
to root a for but we don't have an election OSP FDR and PDI elections do not take place on cereal point
to point links so in a fool once again it's formed a full relationship to write a five but no election
took place on the serial link on the serial interface there was no election and election did take place
on the ether net link and therefore we have a D.R. BTR and in this example another D or other so on
this part of the network the switch we have a designated Rada elected no designated Rada was elected
on the serial link what about on this Ethan a link between Rada five and wrote a six back on Rada five
notice Rada five became the designated Rada on this segment because there are no other rorters running
Oh SPF on that segment so if we enable o SPF on RORT a 6 1 happens show IP 0 SPF interface brief router
6 has become a PDR it's formed a relationship with Rod a 5 show IPO SPF neighbor we can see that right.
Five is the designated rudder full relationship between rudder six and rudder five right.
Six is the BTR so in answer to the questions How many dealers are elected in this topology.
Answer is to how many BDO hours are elected in this topology.
The answer is to write a one and Root a five or designated Rodders write a two and write a six are backup
designated route or BDO RS write a three and write a four on the segment are D or others.
So what you need to know is that a designated writer is elected on a per segment basis but only on broadcast
multi access or non broadcast multi axis links.
In other words links or interfaces where you can have more than one product connected to that single
segment or single subnet so as an example if we added another link between right of 1 and root of 4
we would end up seeing that one of these writers is the designated Rada on the segment and to show you
that erotic can be ADR as well as a BTR or D or other what all D is no shut the link on Rada for first
and configure rather for first so that it becomes the D.R. on that link.
So show IP or SPF interface brief on Fost Ethan at 0 1 we are in the White state so it's waiting for
another router might take it a while so while we're doing that too let's configure an IP address on
router 1 but I won't no shut the interface so that interface is shut I'll configure an IP address on
the interface but I want to know shut it yet notice a 4 has become the designated Rada on this segment
so now and write a one oh no shut the interface show IP who is P.F. interface brief relationship is
formed and when I present to know we can see that brought a 1 is a backup designated rata on gigabyte
0 1 so we've changed the topology slightly now we have a designated Rata which is rather one over here
at designated Rata here which is not a 4 and it designate errata here which is rather a 5 about a 6
is a backup designated rata on the segment on this layer to segment write it to is a backup designated
rota and on this segment write a 1 is a backup designate Rata so notice on write a 1 it's a designated
rata on one segment and a backup designated rata on another segment designated Rod as backup designated
routers are chosen on a per segment basis but only on multi axis networks or segments I hope you found
the video useful if you enjoyed it please like it and please subscribe to my YouTube channel I wish
you all the very best.