+
+ +
+

BRAS tuning

+

Recommendations for BRAS (Broadband Remote Access Server) performance.

+
+

Network tuning

+
+

Disable kernel mitigations to maximize performance

+

Edit file /etc/default/grub

+
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

+
$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:

+
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:

+
ethtool -g eth0
+
+
+
+
+

Fix Download speed problem (shaper)

+

Change shaper from htb to tbf

+
[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

+
[shaper]
+rate-limit=888/888
+
+
+
+
+

Change PPPoE MTU

+

You can adjust allowed PPPoE min/max MTU/MRU settings: +nano /etc/accel-ppp.conf

+
[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

+
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

    2. +
+
rm /lib/systemd/network/99-default.link
+
+
+
    +

  1. Change /lib/udev/rules.d/99-systemd.rules

    2. +
+
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"

+
    +

  1. Change /lib/udev/rules.d/80-ifupdown.rules

    2. +
+
SUBSYSTEM=="net", ACTION=="add|remove", KERNEL!="ppp*|ipoe*", RUN+="ifupdown-hotplug"
+
+
+

Add KERNEL!="ppp*|ipoe*"

+
+
+
+ + +
+