IPv4 library

Table of Contents

• IPv4
  • Functionality
  • Example use

IPv4

The IPv4 library provides functions for creating and manipulation IPv4 packets.

Functionality

• Create IPv4 packets of any length
• Create and extract IPv4 headers
• Verify checksum of IPv4 packets

Other libraries in IPv4 are:

• UDP
• ICMP
• TCP

More details in nw_ipv4_pkg

Example use

Include the libraries:

library nw_util;
context nw_util.nw_util_context;
library nw_ipv4;
context nw_ipv4.nw_ipv4_context;

Assume the variable v_payload contains the IPv4 payload, for example an UDP packet. The variables are defined:

variable v_header   : t_ipv4_header; -- header record
variable v_ipv4_pkt : t_slv_arr(0 to 1500)(7 downto 0); -- byte array
variable v_len      : natural;

First setup the header, then calculate the total IPv4 packet length before creating the packet.

v_header                   := C_DEFAULT_IPV4_HEADER; -- copy default header
v_header.src_ip            := x"c0a820fe"; -- change source IP
v_len                      := f_ipv4_create_pkt_len(v_header, v_payload); -- calculate total packet length
v_ipv4_pkt(0 to v_len - 1) := f_ipv4_create_pkt(v_header, v_payload); -- create the packet

The variable v_ipv4_pkt is an 8-bit array. This can of course be rearranged to any word width with f_repack .

v_ipv4_pkt_64 := f_repack(v_ipv4_pkt, 64, C_MSB_FIRST); -- repack to 64bit words (padded with zeros if required)

See further examples in the test bench nw_ipv4_tb.vhd.