IP Routing 36 Steps

[Pravin]

Can anyone provide some guidance please?

So that I am clear on this, I just wanted some clarification with regards the 36 steps. CCNA book sixth edition.

Page 334

Step 20- "A packet is then created including the source and destination addresses, Protocol filed and payload. The destination is now Host A"

Is the Destination: Host A IP and MAC Address or the Default gateway IP and Mac Address?

and Source: Host B IP and MAC Address? or just IP Address?


Step 24 (page 335) "The Data Link layer frames the packet of information and includes the following in the header:

The destination and source hardware addresses (I'm i correct in saying that this is Host B and the default gateway MAC address?)

On page 336 (near the bootom of the page)
"C:\ >arp -a
Interface: 172.16.10.2--- 0x3"
IP Address- 172.16.10.1
Physical Address- 00-15-05-06-31-b0
Type- Dynamic

Internet Address- 172.16.20.1
Physical Address- 00-15-05-06-31-b0
Type- Dynamic"


1: what is the 0x3?
2: The Physical address for both IP addresses are the same here but different to the ones on page 334 ie:

for 172.16.10.1 it shows as 00d0.58ad.06aa
and 172.16.20.1 shows as 00d0.58ad.05f4

Why is this different? Have I got things mixed up?


it says
"Did you notice that the hardware (MAC) address that Host A uses to get to Host B is the LAB E0 interface?

Many thanks in advance.

[enerside]

Step 20 - The destination IP in the packet will be the IP address of host A and the source IP will be the IP address of host B.

Keep in mind - Packet = network layer = IP address
Frame = data link layer = mac address.

The IP in the packet will not change during transit, the mac used in the frame will change based on where the frame is made and where it is going keeping in mind that mac addressing is used on a local network segment only and is not used to get to a remote segment.

Step 24 - The source address in the frame will be the mac of host B and the destination address in the frame will be the mac of the router.

The question about the arp cache on the host is not a typo. Remember that mac addressing is only used on the local segment, so in order for the host to talk to 172.16.20.1, it still must go through the router, therefore the frame from host A must still be addressed to 00-15-05-06-31-b0.

I wouldn't worry about the 0x3, I think it's just an identifier that corresponds to a particular interface on the computer.

[Pravin]

Thanks for the information. The 36 steps makes a lot more sence now.