IPv6 library

Table of Contents

• IPv6
  • Functionality
  • Example use

IPv6

The IPv6 library provides functions for creating and manipulation IPv6 packets.

Functionality

• Create IPv6 packets of any length
• Create and extract IPv6 headers including extension headers
• Verify checksum of IPv6 packets

Other libraries in IPv6 are:

• UDP
• ICMP
• TCP

More details in nw_ipv6_pkg

Example use

Include the libraries:

library nw_util;
context nw_util.nw_util_context;
library nw_ipv6;
context nw_ipv6.nw_ipv6_context;

Assume the variable v_payload contains the IPv6 payload, for example an UDP packet. The variables are defined:

variable v_header   : t_ipv6_header; -- header record
variable v_ipv6_pkt : t_slv_arr(0 to 1500)(7 downto 0); -- byte array
variable v_len      : natural;

First setup the header, then calculate the total IPv6 packet length before creating the packet.

v_header                   := C_DEFAULT_IPV6_HEADER; -- copy default header
v_header.src_addr          := f_ipv6_addr_2_slv_arr("2102:ec7::2"); -- change source address
v_len                      := f_ipv6_create_pkt_len(v_header, v_payload); -- calculate total packet length
v_ipv6_pkt(0 to v_len - 1) := f_ipv6_create_pkt(v_header, v_payload); -- create the packet

Extension headers are used by first defining a variable holding a list of extension headers, then adding individual extension headers to this list.

v_ext_header_list : t_ext_header_list := C_DEFAULT_EXT_HEADER_LIST; -- init the extension header list to empty
v_ext_header      : t_extension_header; -- extension header to be added to list

Extension headers can added to the list in any order (note that RFC 2460 recommends a specific order).
Add Hop-by-Hop Options Header:

v_ext_header              := C_DEFAULT_EXT_HEADER; -- start with a default header
v_ext_header.header_type  := C_HOPOPT; -- Hop-by-Hop Options
v_ext_header.hdr_ext_len  := 1; -- 16byte total length
v_ext_header.data(0 to 1) := (x"01", x"0c"); -- PadN option
v_ext_header_list         := f_ipv6_add_ext_header(v_ext_header_list, v_ext_header); -- add header to list. Note that v_ext_header.next_header is updated here.

Add Routing Header:

v_ext_header               := C_DEFAULT_EXT_HEADER; -- start with a default header
v_ext_header.header_type   := C_IPV6_ROUTE; -- Routing Header
v_ext_header.routing_type  := x"00";  -- routing type 0
v_ext_header.segments_left := x"01";
v_ext_header.hdr_ext_len   := 1; -- 16byte total length
v_ext_header.data(0 to 7)  := f_ipv6_addr_2_slv_arr("4200:8a::44");
v_ext_header_list          := f_ipv6_add_ext_header(v_ext_header_list, v_ext_header); -- add header to list. 

Add Fragment Header:

v_ext_header                  := C_DEFAULT_EXT_HEADER; -- start with a default header
v_ext_header.header_type      := C_IPV6_FRAG; -- Fragment header
v_ext_header.framgment_offset := "0011001000000"; -- 13bit offset
v_ext_header.m_flag           := '0'; -- last fragment
v_ext_header.identification   := x"00000042"; 
v_ext_header.hdr_ext_len      := 0; -- 8byte total length
v_ext_header_list             := f_ipv6_add_ext_header(v_ext_header_list, v_ext_header); -- add header to list.

Add Destination Options Header:

v_ext_header              := C_DEFAULT_EXT_HEADER; -- start with a default header
v_ext_header.header_type  := C_IPV6_OPTS; -- Destination Options
v_ext_header.hdr_ext_len  := 0; -- 8byte total length
v_ext_header.data(0 to 3) := (x"01", x"02"); -- PadN option
v_ext_header_list         := f_ipv6_add_ext_header(v_ext_header_list, v_ext_header); -- add header to list.

Add Authentication Header (RFC 2402):

v_ext_header               := C_DEFAULT_EXT_HEADER; -- start with a default header
v_ext_header.header_type   := C_AH; -- Authentication Header
v_ext_header.hdr_ext_len   := 4; -- Note! Number of 4byte words minus 2
v_ext_header.spi           := x"12345678"; -- Security Parameters Index
v_ext_header.seq_no        := x"000000f4"; -- sequence number
v_ext_header.data(0 to 11) := f_gen_prbs(C_POLY_X16_X15_X13_X4_1, 8, 12); -- random payload
v_ext_header_list          := f_ipv6_add_ext_header(v_ext_header_list, v_ext_header); -- add header to list.

Finally create the IPv6 packet with extension headers:

v_len                      := f_ipv6_create_pkt_len(v_header, v_payload, v_ext_header_list); -- calculate total packet length
v_ipv6_pkt(0 to v_len - 1) := f_ipv6_create_pkt(v_header, v_payload, v_ext_header_list); -- create the packet

See further examples in the test bench nw_ipv6_tb.vhd.