Policy-Based QOS Configuration

:The latest 4.4.0 and 4.2.12 distributions utilize an improved policy-based configuration for quality of service. The default rc.qos script has examples that use a new QoS library of functions, greatly simplifying QoS configuration.

:Services define a type of traffic or service. Policies prioritize services, define how the traffic is queued and set minimum and maximum rates as a percentage of the maximum rate. Interface definitions apply a policy to an interface and define the maximum input and output rates as well as the maximum allowed latency for queued traffic. Because policy rates are specified using percentages a policy can be applied to multiple interfaces which may have differing input and output rates.

====QOS_SERVICE====
:The QOS_SERVICE command defines parameters that match a type of service such as Web traffic or SMTP traffic. ImageStream [[QOS Pre-Defined Services|pre-defines many services]] that can be added to or modified.

:Currently only tc filter matches are supported. See the Linux Advanced Routing and Traffic Control guide for more information on tc filter matching.

:'''Usage:''' QOS_SERVICE --name <service_name> [--init] --tc_match <tc_filter_command_match>
:'''Example:'''
:Create a new service called ims1 that matches traffic to and from 205.159.243.5
 QOS_SERVICE --name ims1 --init --tc_match protocol ip u32 match ip src 205.159.243.5
 QOS_SERVICE --name ims1 --tc_match protocol ip u32 match ip dst 205.159.243.5

:It is also possible to add on to a pre-defined service. Simply omit the '--init' option to add another match to a service.
:'''Example:'''
:In addition to the IP ToS bit matches also match on the SIP server's IP at 205.159.243.5.
 QOS_SERVICE --name voip --tc-match protocol ip u32 match ip src 205.159.243.5
 QOS_SERVICE --name voip --tc-match protocol ip u32 match ip dst 205.159.243.5

====QOS_POLICY====
:The QOS_POLICY command prioritizes and rate-limits services. Low latency queueing and class-based queueing are supported.
:Low latency queueing provides a strict priority-based first-in-first-out (FIFO) queue which does not rate shape the traffic. This queueing method is preferred for real-time traffic such as VoIP and routing protocols.
:Priorities range from 0 to 9. Lower values indicate higher priority.
:Minimum and maximum values are expressed as percentages ranging from 1 to 100. The actual rate will be calculated using this percentage and the interface's real bandwidth.
:Class-based queueing provides prioritization but also performs rate shaping. This queueing method is preferred for non-realtime traffic such as Web and E-mail.
:'''LLQ Usage:''' QOS_POLICY --name <policy_name> --type llq --service <service_name> --prio <priority 0-9> --max <max_percent>
:'''Example:'''
 QOS_POLICY --name default --type llq --service voip --prio 0 --max 90

:'''CBQ Usage:''' QOS_POLICY --name <policy_name> --type cbq [--default | --service <service_name>] --prio <priority 0-9> --min <min_percent> --max <max_percent>
:'''Example:'''
:Set the default traffic class to priority 5 and prioritize TCP ACKs higher than other traffic.
 QOS_POLICY --name default --type cbq --default --prio 5 --min 10 --max 75
 QOS_POLICY --name default --type cbq --service ack --prio 3 --min 10 --max 40

====QOS_IFACE====
:The QOS_IFACE command applies a policy to an interface. The maximum input and output rates are specified in Kbps (Kilobits per second). Latency is specified in milliseconds.
:Fair queueing can also specified on the interface. ImageStream's PUFQ, standard fair-queueing and simple first-in-first-out (FIFO) queueing are options.

:'''FIFO Usage:''' QOS_IFACE --name <interface_name> --policy <policy_name> --max_in <input_rate_in_Kbps> --max-out <output_rate_in_Kbps> --max-latency <max_latency_in_ms>
:'''Example:'''
:Assign the default policy to Ethernet0 which has a 3.0 Mbps input and 640 Kbps output rate. We want 150 ms max latency.
 QOS_IFACE --name eth0 --policy default --max_in 3000 --max_out 640 --max_latency 150

:'''Fair-Queueing Usage:''' QOS_IFACE --name <interface_name> --policy <policy_name> --max_in <input_rate_in_Kbps> --max-out <output_rate_in_Kbps> --max-latency <max_latency_in_ms> --fair_queue 
:[[sfq advanced options]]

:'''Example:'''
:Assign the default policy to Ethernet0 using fair queueing which has a 3.0 Mbps input and 640 Kbps output rate. We want 150 ms max latency.
 QOS_IFACE --name eth0 --policy default --max_in 3000 --max_out 640 --max_latency 150 --fair_queue

:'''PUFQ Usage:''' QOS_IFACE --name <interface_name> --policy <policy_name> --max_in <input_rate_in_Kbps> --max-out <output_rate_in_Kbps> --max-latency <max_latency_in_ms> --pufq --pufq_iface_type <inside | outside | nat_inside | nat_outside>
:[[pufq advanced options]]

:'''Example:'''
:Assign the default policy to Ethernet0 using PUFQ which has a 3.0 Mbps input and 640 Kbps output rate. We want 150 ms max latency.
 QOS_IFACE --name eth0 --policy default --max_in 3000 --max_out 640 --max_latency 150 --pufq --pufq_iface_type outside

:'''ATM/DSL Adjustments'''
:Starting in 4.4.0-72 and 4.2.12-46 a new ''--calc_atm'' parameter was added to the QOS_IFACE statement to allow the QOS subsystem to calculate ATM/AAL5 overhead for each packet being transmitted. This allows the system to specify the exact ATM data rate for the link.

:'''Example:'''
:An 3.0 Mb / 512 K DSL link has synced up at 3520000 bps down and 768000 bps up.
 QOS_IFACE --name eth0 --policy default --max_in 3520 --max_out 768 --max_latency 150 --fair_queue --calc_atm

====Advanced Example====
<pre>
################################################################################
#
# Advanced example
# Override the voip service definition. We define voip as traffic to/from
# 192.168.0.35
# Policy:
#  Low Latency Queues:
#   voip: Low Latency Queue with highest priority and maximum of 90% of the
#         interface's bandwidth.
#  Class-Based Queues:
#   telnet: Highest priority with min of 10% and max 40%.
#   ssh: Lower priority than telnet with min 10% and max 40%.
#   tcp acks: Lower priority than ssh with min of 10% and max of 40%.
#   smtp: Lowest priority with min of 10% and max 60%.
#   default: Priority 5 (just above smtp) with min 10% max 95%
#
# Interface:
#  Apply the policy "default" to interface eth0 with the maximum input rate of
#  3000 Kbps (3.0 Mbps) and maximum output rate of 640 Kbps with a maximum
#  queueing latency of 150 ms. Configure PUFQ with nat_outside as the interface type
#  since this interface performs SNAT on user traffic.
#
QOS_SERVICE --name voip --init --tc_match protocol ip u32 match ip src 192.168.0.35/32
QOS_SERVICE --name voip        --tc_match protocol ip u32 match ip dst 192.168.0.35/32
QOS_POLICY --name default --type llq --service voip     --prio 0 --max 90
QOS_POLICY --name default --type cbq --init --default   --prio 5 --min 10 --max 95
QOS_POLICY --name default --type cbq --service telnet   --prio 1 --min 10 --max 40
QOS_POLICY --name default --type cbq --service ssh      --prio 2 --min 10 --max 40
QOS_POLICY --name default --type cbq --service ack      --prio 3 --min 10 --max 40
QOS_POLICY --name default --type cbq --service smtp     --prio 6 --min 10 --max 60

QOS_IFACE --name eth0 --policy default --max_in 3000 --max_out 640 --max_latency 150 --pufq --pufq_iface_type nat_outside
</pre>