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:

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.

Table of Contents

IPv4

Functionality

Example use