IPv6, 2nd Edition

170 Part Two • IPv6 Protocols

trades places with the first node on the Routing Header list (Node C). Once

this packet is received at Node C, the Segments Left field goes from 2 to 1,

and Node C’s address goes back to the Routing Header to be replaced by

Node D’s address. The process repeats for Node E, the final destination,

where the Routing Header list contains just the nodes that were originally

specified to be stops en route from Node A to Node E.

Routers may be required to modify Routing Headers of the packets they

process, but some header extensions may not be modified at all, like the

Fragment Header.

9.3 Fragment Header

To send a payload that is too ...