2.0 KiB
id, aliases, tags
| id | aliases | tags | |
|---|---|---|---|
| 1777801183-SYMV |
|
The Life of a Packet
Network Topology
We will follow a packet from PC1 to PC4
mac address for the machine
PC 1 -> 1111 R1 -> G0/2 aaaa -> G0/0 -> bbbb R2 -> G0/0 cccc -> G0/1 -> dddd R4 -> G0/0 eeee -> G0/1 -> ffee PC 4 -> 4444
SRC: 192.168.1.1 DST: 192.168.4.1
PC 1 is in the 192.168.1.0/24 network it need to send the packet in another network
First PC will use An ARP request it need to find the next interface for the sending the packet
SRC IP: 192.168.1.1 DST IP: 192.168.1.254 -> gateway DST MAC: ffff.fff.fff -> all of the interface Src MAC: 1111
ARP request = Broadcast ARP requply = UNICAST
R1 will answer with an ARP Reply
SRC IP: 192.168.1.254 DST IP: 192.168.1.1 -> PC1 DST MAC: 1111 Src Mac: aaaa
Now PC1 now the Mac address of the default gateway and will encapsulated the packet with the internet header
+-----------------+--------+ |SRC: 192.168.1.1 |Dst:aaaa| |DST: 192.168.4.1 |Src:1111| +-----------------+--------+
R1 Receive the packet and watch the routing table and see
Destination Next Hop 192.168.4.0/24 192.168.12.2
R1 will encapsulated the packet for sending to R2 He will have tot do an ARP request R2 send a arp reply Same process as above
+-----------------+--------+ |SRC: 192.168.1.1 |Dst:cccc| |DST: 192.168.4.1 |Src:bbbb| +-----------------+--------+
R2 Receive the packet and watch the routing table R2 will encapsulated the packet for sending to R4 He will have tot do an ARP request R4 send a arp reply Same process as above
+-----------------+--------+ |SRC: 192.168.1.1 |Dst:eeee| |DST: 192.168.4.1 |Src:dddd| +-----------------+--------+
R4 Receive the packet and watch the routing table R4 will encapsulated the packet for sending to PC4 He will have tot do an ARP request PC4 send a arp reply Same process as above
+-----------------+--------+ |SRC: 192.168.1.1 |Dst:4444| |DST: 192.168.4.1 |Src:ffee| +-----------------+--------+