In this topology we have two routers and two pieces.
This is a newly configured topology.
The writers have just booted up and have no configuration.
So for example show IP interface brief on Route 1 shows that all interfaces are shut down and no IP
addresses are configured.
What I'll do is no shut interface serial to slash a zero.
The waiting to face on route one and I'll do something similar on brought it to write it to also has
no configuration so no shut
show IP interface brief as you can see the interfaces up on both sides
show interface serial to slash a zero but I'd like to point out is the encapsulation used which is HDL
LC by default on Cisco routers serial interfaces use HDL see as the encapsulation.
So what we could do is go into that interface and give the rod an IP address of say 10 to 1 or 2 to
1 and use a session 30 mosque or D something similar on a t IP address tended one to two to two
can write a 1 ping right to yes it can can write a 2 ping wrote a 1 yes it can show run interface serial
to slash 0 all we had to do was no shut the interface we didn't have to configure an encapsulation we
didn't have to configure clock rate you only have to configure clock right if you're using a back to
back cable and your rudder is the DC side of the cable here.
Both sides of the DTV so we didn't have to configure a clock right.
Let's have a look at each DLC frames.
So do why shock capture
on router ones serial interface
what we can see here is the protocol shown is slop
but notice we've got h see and then the Cisco slop protocol which is used for order configuration.
Here we have a CTP message so Cisco HTC C is the encapsulation used at least to notice the protocol
is referenced as 2000 which is Cisco Discovery Protocol and we can see information about the device.
So rather 1 is a 37 25 and is using interface serial to slash 0 his Roddick to or so using serial interface
to slash 0
if we do a ping
we should see ICMP and there we go.
So ICMP
Adelaide to its once again HD you'll see.
So if we look at the actual frame the encapsulation type is HDR you'll see it's not Ethernet so on this
one interface we're using an HDL seeing caps relation.
Notice the protocol reference is the famous x 0 x 800 which means IP version for at least three years
IP version 4.
You can see the source IP address and destination IP address in the packet
the protocol is ICMP you can see it's an echo.
He has the echo reply scrolling back to the top.
It's once again HD see there's the protocol type.
Source IP address is 10 1 1 2 going to 10 1 2 1.
And it's an echo.
Reply
So Cisco HD C or C HD LC has this protocol field denoting the Hialeah protocol.
That's IP vision for let's configure IP version 6 So IP vs 6 address 2001 colon colon 1 colon colon
one slash 64 on route to interface serial to slash zero IP vs 6 address.
2001 colon 1 colon colon 2 slash 64
ping 2001 colon 1 colon 2 ping succeeds in why shock capture we see the ICMP messages.
So this is the ping from Rada want to write it too.
Notice the protocol type 86 D.D..
It's a different protocol type to IP version for Cisco HDFC logic to run multiple Hialeah protocols
across the same link because of this protocol field.
So once again there is IP version 6 and scrolling up here is IP version for and here is CTP all using
different protocol types.
So the layer to encapsulation has referencing a higher layer protocol we would see something similar
on an Ethan at frame.
So on router 1 interface if 0 slash 0.
No shut IP address 10 1 1 1 2 4 5 2 4 5 2 4 5 0.
On the P.C. we'll give it an IP address of 10 to 1 2 1 but eleven with a mosque
and I'll set the gateway to 10 at 1 1 1 so paying tendered wandered wandered 1 P.S. camping wrote a
1 and if we started captcha on that interface.
So we're going to capture traffic on the road.
Notice the frame is Ethan a 2 let's send a ping again so there is ICMP packet.
Notice the protocol type for IP vision for is 0 800 which is what we saw on the HTC frame so he has
HD you'll see.
Notice the protocol field so when you send packets across a to the shows you quite clearly that the
layer to encapsulation changes but the high layer protocols are maintained or kept encapsulation used
Chia is Ethan it to encapsulation used here is HTC encapsulation here would be Ethan to once again in
this example so in order to interface if there is such zero no shut IP address tendered wondered.
3 to 1 as an example.
P.S. 2 IP address tendered 1.0 three to twelve put the mosque in default gateway
paying 10 dot wonder to 3 to 1 that works only enable routing protocol here quickly to allow the writers
to talk to each other and this will give us another protocol to capture in y shock
so enable a whisper from all interfaces started capture on this interface
so we have three wide shot captures going several interface face the seating at interface and the seats
the net interface P.S. One should if SPF has converged be able to paying PCI to which it can.
So the pings are succeeding let's have a look at the frame over here on the Internet segment so there's
the frame you can see the Ethernet type is Ethernet to source MAC address destination MAC address which
is the router protocol is IP vision for just to prove that that's a router
show interface zero slash 0
notice the MAC address is c to a 1
3 f 8 0 0 0 0 which is correct so the P.C. sending the traffic to the local Rada using ethernet to.
In other words Ethernet encapsulation at least 3 the source and destination on the TPC is on the HDL
C capture
there's the same IP addresses of the pieces at layer 3 but notice at layer two the encapsulation is
HDL C and there are no mac addresses MAC addresses are only used on Ethernet they're not used in HDL
C HDL C links are point to point there's no need to have mac addresses anything that you send out of
this interface is going to arrive on this interface and vice versa with Ethernet allows multiple devices
to connect to the same segment so there's no need to have mac addresses in H2 you'll see it simply references
the highlight of protocol and specifies that this is a unique cost packet What about on the side.
So here's the ping source and destination IP addresses of the same.
Notice however that it's Ethernet once again so Ethan at 2 in this case the source MAC address is Rod
to show interface fast ethernet zero slash a zero notice the MAC address C 2 0 2 3 F A 8 for zeros that's
the router talking to the P.C. in this case P.S. to the Ethernet type field specifies IP version for
as the highlight protocol and he has IP packet and here's the ICMP information
the encapsulation changes on every link MAC addresses are used on the Ethernet segments MAC addresses
are not used in HD see.