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