ELTEX MES3108 - 5.31 Quality of Services (QoS); 5.31.1 QoS Configuration

208 MES3000 Ethernet switch series
5.31 Quality of Services (QoS)
All ports of switch apply FIFO principle for packets queue that means "first in—first out". This
principle may cause some issues in case of intensive traffic because the device will ignore all packets
which are not included to the FIFO queue buffer, i. e. such packets will be permanently lost. This can be
solved by organising queues by traffic priority. The QoS mechanism (Quality of Service) implemented in
MES3000 switches allows organisation of 8 queues by packets priority depending on the type of data
being sent.
Queue service
Queuing algorithms allow providing traffic of different classes with different level of QoS. Every
queue deals with packets with certain priorities. High-priority traffic must be processed with minimal
delay and must not hold the entire bandwidth. Also traffic with another type of priority must be processed
according to its priority. Queuing algorithm is implemented through tail-drop mechanism, use of virtual
packet buffers and queue size settings.
Queue size and virtual packet buffer parameters are set by default in a switch. These settings can be
changed if it is necessary by «qos tail-drop profile» mechanism.
5.31.1 QoS Configuration
Global Configuration Mode Commands
Command line request in the global configuration mode appears as follows:
console(config)#
Table 5.254 Global configuration mode commands
Command
Value/Default Value
Action
qos [basic | advanced
[portstrusted |
portsnottrusted]]
-/basic
Enables QoS in the switch.
- basic—QoS basic mode;
- advanced—QoS advanced configuration mode which
provides all commands of QoS configuration;
- ports-trusted–in this sub-mode packets are transmitted to
egress queue according to the fields in that packets;
- ports-not-trusted–in this sub-mode all packets are directed
to egress queue 0 by default. To transmit packets to another
queue, assign policy-map on the incoming interface.
no qos
Sets FIFO data transfer mode.
QoS settings will be deleted in this case.
qos advanced-mode trust
{cos | dscp |cos-dscp}
-/disabled
Set trust mode on the ports in QoS advanced configuration
mode and ports-trusted sub-mode.
- cos–port trusts 802.1p User priority value;
- dscp–port trusts DSCP value in IPv4/IPv6 packets;
- cos-dscp–port trusts both levels, however DSCP takes
precedence over 802.1p.
no qos advanced-mode
trust
Set the mode by default
qos statistics interface
-/disable
Enable mode for traffic classifying statistics on physical
interfaces
no qos statistics interface
Disable statistics mode
qos tail-drop profile
profile_id
profile_id: (1..4)
Create qos tail-drop profile.
no qos tail-drop profile
profile_id
Remove qos tail-drop profile.