24.4. IPv4 Versus IPv6IPv6 is very similar to IPv4 as far as the L3 to L4 protocol interface is concerned. L4 protocols can register via inet6_add_protocol and deregister them via inet6_del_protocol, both defined in net/ipv6/protocol.c. Handlers are stored in a table called inet6_protos of the same size (MAX_INET_PROTOS) used by IPv4. L4 protocols that run on top of IPv6 are represented by inet6_protocol data structures (defined in include/net/protocol.h), whose definition is almost identical to the one used by IPv4. The only differences are in the prototypes of the handler and err_handler function pointers and the use of a flag instead of an integer to store such information as the presence of security policies. The field used by IPv6 to identify the upper-layer protocol in the IPv6 header is called next_header and is an 8-bit value like the one used by IPv4. See Figure 24-8 for the location of the field in the header. Figure 24-8. IPv6 header and next_header protocol identifier |
Tuesday, October 20, 2009
Section 24.4. IPv4 Versus IPv6
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