doc: Add build instructions for Arch Linux

Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com>

doc/developer/building-frr-for-archlinux.rst

@@ -0,0 +1,129 @@
+Arch Linux
+================
+
+Installing Dependencies
+-----------------------
+
+.. code-block:: console
+
+   sudo pacman -Syu
+   sudo pacman -S \
+      git autoconf automake libtool make cmake pcre readline texinfo \
+      pkg-config pam json-c bison flex python-pytest \
+      c-ares python systemd python2-ipaddress python-sphinx \
+      systemd-libs net-snmp perl libcap
+
+.. include:: building-libyang.rst
+
+Protobuf
+^^^^^^^^
+
+.. code-block:: console
+
+   sudo pacman -S protobuf-c
+
+ZeroMQ
+^^^^^^
+
+.. code-block:: console
+
+   sudo pacman -S zeromq
+
+Building & Installing FRR
+-------------------------
+
+Add FRR user and groups
+^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code-block:: console
+
+   sudo groupadd -r -g 92 frr
+   sudo groupadd -r -g 85 frrvty
+   sudo useradd --system -g frr --home-dir /var/run/frr/ \
+   -c "FRR suite" --shell /sbin/nologin frr
+   sudo usermod -a -G frrvty frr
+
+Compile
+^^^^^^^
+
+.. include:: include-compile.rst
+
+Install FRR configuration files
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code-block:: console
+
+   sudo install -m 775 -o frr -g frr -d /var/log/frr
+   sudo install -m 775 -o frr -g frrvty -d /etc/frr
+   sudo install -m 640 -o frr -g frrvty tools/etc/frr/vtysh.conf /etc/frr/vtysh.conf
+   sudo install -m 640 -o frr -g frr tools/etc/frr/frr.conf /etc/frr/frr.conf
+   sudo install -m 640 -o frr -g frr tools/etc/frr/daemons.conf /etc/frr/daemons.conf
+   sudo install -m 640 -o frr -g frr tools/etc/frr/daemons /etc/frr/daemons
+
+Tweak sysctls
+^^^^^^^^^^^^^
+
+Some sysctls need to be changed in order to enable IPv4/IPv6 forwarding and
+MPLS (if supported by your platform). If your platform does not support MPLS,
+skip the MPLS related configuration in this section.
+
+Edit :file:`/etc/sysctl.conf`[*Create the file if it doesn't exist*] and 
+append the following values (ignore the other settings):
+
+::
+
+   # Enable packet forwarding for IPv4
+   net.ipv4.ip_forward=1
+
+   #  Enable packet forwarding for IPv6
+   net.ipv6.conf.all.forwarding=1
+
+Reboot or use ``sysctl -p`` to apply the same config to the running system.
+
+Add MPLS kernel modules
+"""""""""""""""""""""""
+
+To
+enable, add the following lines to :file:`/etc/modules-load.d/modules.conf`:
+
+::
+
+   # Load MPLS Kernel Modules
+   mpls_router
+   mpls_iptunnel
+
+
+And load the kernel modules on the running system:
+
+.. code-block:: console
+
+   sudo modprobe mpls-router mpls-iptunnel
+
+Enable MPLS Forwarding
+""""""""""""""""""""""
+
+Edit :file:`/etc/sysctl.conf` and the following lines. Make sure to add a line
+equal to :file:`net.mpls.conf.eth0.input` for each interface used with MPLS.
+
+::
+
+   # Enable MPLS Label processing on all interfaces
+   net.mpls.conf.eth0.input=1
+   net.mpls.conf.eth1.input=1
+   net.mpls.conf.eth2.input=1
+   net.mpls.platform_labels=100000
+
+Install service files
+^^^^^^^^^^^^^^^^^^^^^
+
+.. code-block:: console
+
+   sudo install -m 644 tools/frr.service /etc/systemd/system/frr.service
+   sudo systemctl enable frr
+
+Start FRR
+^^^^^^^^^
+
+.. code-block:: shell
+
+   systemctl start frr

doc/developer/building.rst

@@ -26,3 +26,4 @@ Building FRR
    building-frr-for-ubuntu1404
    building-frr-for-ubuntu1604
    building-frr-for-ubuntu1804
+   building-frr-for-archlinux