About Lesson
IPv4 Packet
Explain the role of the major header fields in the IPv4 packet.
IPv4 Packet Header
- IPv4 is the primary communication protocol for the network layer.
- The network header has many purposes:
- It ensures the packet is sent in the correct direction (to the destination).
- It contains information for network layer processing in various fields.
- The information in the header is used by all layer 3 devices that handle the packet
IPv4 Packet Header Fields
The IPv4 network header characteristics:
- It is in binary.
- Contains several fields of information
- Diagram is read from left to right, 4 bytes per line
- The two most important fields are the source and destination.
- Protocols may have may have one or more functions.
- Significant fields in the IPv4 header:
| Function | Description |
|---|---|
| Version | This will be for v4, as opposed to v6, a 4 bit field= 0100 |
| Differentiated Services | Used for QoS: DiffServ – DS field or the older IntServ – ToS or Type of Service |
| Header Checksum | Detect corruption in the IPv4 header |
| Time to Live (TTL) | Layer 3 hop count. When it becomes zero the router will discard the packet. |
| Protocol | I.D.s next level protocol: ICMP, TCP, UDP, etc. |
| Source IPv4 Address | 32 bit source address |
| Destination IPV4 Address | 32 bit destination address |
Other related topics
| Topic Title | Topic Objective |
|---|---|
| Network Layer Characteristics | Explain how the network layer uses IP protocols for reliable communications. |
| IPv4 Packet | Explain the role of the major header fields in the IPv4 packet. |
| IPv6 Packet | Explain the role of the major header fields in the IPv6 packet. |
| How a Host Routes | Explain how network devices use routing tables to direct packets to a destination network. |
| Router Routing Tables | Explain the function of fields in the routing table of a router. |
Other useful information
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