Appendix B. IPv6 Header Format

Although this specific material is not tested on the ROUTE exam, it might help you gain a better understanding of the structure of IPv6.

The IPv6 header is similar to the IPv4 header. The largest changes have to do with the larger addresses, aligning fields to 64-bit boundaries, and moving fragmentation to an extension header.

The fields are

Version: 6.

Priority: Similar to DSCP in version 4, this 8-bit field describes relative priority.

Flow: 20-bit flow label enables tagging in a manner similar to MPLS.

Length: The length of the data in the packet.

Next Header: Indicates how the bits after the IP header should be interpreted. Can indicate TCP or UDP, or it can show an extension header.

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