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+BRAS tuning
+===========
+
+Recommendations for BRAS (Broadband Remote Access Server) performance.
+
+
+Network tuning
+--------------
+
+Disable kernel mitigations to maximize performance
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Edit file ``/etc/default/grub``
+
+.. code-block:: sh
+
+  GRUB_CMDLINE_LINUX_DEFAULT="intel_idle.max_cstate=0 processor.max_cstate=1 idle=poll quiet mitigations=off"
+
+Additional GRUB CMD arguments:
+
+  * ixgbe.allow_unsupported_sfp=1 - Allow to use not original Intel SFP+ modules
+  * pcie_aspm=off - Disable Active-State Power Management
+
+After saving, please update grub settings 
+
+.. code-block:: sh
+
+  $sudo update-grub
+
+Warning! Enabling the idle loop  (``idle=poll``) parameter can cause 100% CPU utilization on your VM (if you're using virtual enviroments like ProxMox, VMWare, etc.)
+
+
+Disable NIC offloads
+^^^^^^^^^^^^^^^^^^^^
+Disable hardware offloads,increase Tx/Rx buffers and queue length on your NICs to prevent speed problems.
+Please note, that GSO offload changed to tx-gso-partial in Linux kernels 4.15 and later.
+
+Debian ``/etc/network/interfaces``:
+
+
+.. code-block:: sh
+  
+    allow-hotplug eth0
+    iface eth0 inet manual
+        up ethtool -K eth0 tso off gso off gro off rxvlan off txvlan off rx-vlan-filter off ntuple on &> /dev/null
+        up ethtool -K eth0 tx-gso-partial off &> /dev/null
+        up ethtool -G eth0 rx 4096 tx 4096 &> /dev/null
+        up ip link set eth0 txqueuelen 10000 &> /dev/null
+
+Please determine your NIC queue and buffers limit before increase:
+
+.. code-block:: sh
+
+
+  ethtool -g eth0
+
+
+Fix Download speed problem (shaper)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Change shaper from htb to tbf
+
+.. code-block:: sh
+
+  [shaper]
+  …
+  down-limiter=tbf 
+
+
+Default rate limits (shaper)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If radius-server Access-Accept answer has no compatible speed attributes - to prevent unlimited session speed you can add default rate-limits (in Kbps).
+
+``nano /etc/accel-ppp.conf``
+
+.. code-block:: sh
+
+  [shaper]
+  rate-limit=888/888
+
+
+Change PPPoE MTU
+^^^^^^^^^^^^^^^^
+
+You can adjust allowed PPPoE min/max MTU/MRU settings:
+``nano /etc/accel-ppp.conf``
+
+.. code-block:: sh
+
+  [ppp]
+  verbose=1
+  min-mtu=1280
+  mtu=1492
+  mru=1492
+
+Hotplug optimization
+^^^^^^^^^^^^^^^^^^^^
+To generate hotplug events on IPoE interfaces (Debian 10):
+
+``nano /lib/udev/ifupdown-hotplug``
+
+.. code-block:: sh
+
+    case "$ACTION" in
+    add)
+    # these interfaces generate hotplug events *after* they are brought up
+    case $INTERFACE in
+        ppp*|ippp*|isdn*|plip*|lo|irda*|ipsec*
+
+just add ``|ipoe*`` after ``|ipsec*``
+
+repeat with file ``/lib/udev/net.agent``
+
+SYSTEMD-UDEV optimizations
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+1. Delete ``99-default.link`` from ``/lib/systemd/network/`` directory
+
+.. code-block:: sh
+
+    rm /lib/systemd/network/99-default.link
+
+2. Change ``/lib/udev/rules.d/99-systemd.rules``
+
+.. code-block:: sh
+
+    ACTION=="add", SUBSYSTEM=="net", KERNEL!="lo|ppp*|ipoe*", RUN+="/lib/systemd/systemd-sysctl --prefix=/net/ipv4/conf/$name --prefix=/net/ipv4/neigh/$name --prefix=/net/ipv6/conf/$name --prefix=/net/ipv6/neigh/$name"
+
+Add ``|ppp*|ipoe*`` to ``KERNEL!="lo"``
+
+3. Change ``/lib/udev/rules.d/80-ifupdown.rules``
+
+.. code-block:: sh
+
+    SUBSYSTEM=="net", ACTION=="add|remove", KERNEL!="ppp*|ipoe*", RUN+="ifupdown-hotplug"
+
+Add ``KERNEL!="ppp*|ipoe*"``