1.. _networking_with_armfvp:
2
3Networking with Arm FVP User Mode
4#################################
5
6.. contents::
7    :local:
8    :depth: 2
9
10This page is intended to serve as a starting point for anyone interested in
11using Arm FVP user mode networking with Zephyr.
12
13Introduction
14*************
15
16User mode networking emulates a built-in IP router and DHCP server, and routes
17TCP and UDP traffic between the guest and host. It uses the user mode socket
18layer of the host to communicate with other hosts. This allows the use of
19a significant number of IP network services without requiring administrative
20privileges, or the installation of a separate driver on the host on which
21the model is running.
22
23By default, Arm FVP uses the ``172.20.51.0/24`` network and runs a gateway at
24``172.20.51.254``. This gateway also functions as a DHCP server for the GOS,
25allowing it to be automatically assigned with an IP address ``172.20.51.1``.
26
27More details about Arm FVP user mode networking can be obtained from here:
28https://developer.arm.com/documentation/100964/latest/Introduction-to-Fast-Models/User-mode-networking
29
30Using Arm FVP User Mode Networking with Zephyr
31***********************************************
32
33Arm FVP user mode networking can be enabled in any applications and it doesn't
34need any configurations on the host system. This feature has been enabled in
35DHCPv4 client sample.
36See :zephyr:code-sample:`dhcpv4-client` sample application.
37
38Limitations
39*************
40
41* You can use TCP and UDP over IP, but not ICMP (ping).
42* User mode networking does not support forwarding UDP ports on the host to
43  the model.
44* You can only use DHCP within the private network.
45* You can only make inward connections by mapping TCP ports on the host to
46  the model. This is common to all implementations that provide host
47  connectivity using NAT.
48* Operations that require privileged source ports, for example NFS in its
49  default configuration, do not work.
50* If setup fails, or the parameter syntax is incorrect, there is no error
51  reporting.
52