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̈ Chapter 9: Quality of Service LANCOM Reference Manual LCOS 3.50
171
Quality of Service
9.2.1 Guaranteed minimum bandwidths
Hereby you give priority to enterprise-critical applications, e.g. Voice-over-IP
(VoIP) PBX systems or certain user groups.
Full dynamic bandwidth management for sending
Concerning the sending direction, the bandwidth management takes place
dynamically. This means that e.g. a guaranteed minimum bandwidth is only
available, as long as the corresponding data transfer really exists.
An example:
For the transmission of VoIP data of an appropriate VoIP gateway, a band-
width of 256 Kbps is to be guaranteed always. Thereby, each individual VoIP
connection consumes 32 Kbps.
As long as nobody telephones, the entire bandwidth is at the disposal to other
services. Per adjacent VoIP connection 32 Kbps less is available to other appli-
cations, until 8 VoIP connections are active. As soon as a VoIP connection is
terminated, the corresponding bandwidth is available again to all other appli-
cations.
For correct functioning of this mechanism, the sum of the configured
minimum bandwidth must not exceed the effectively available trans-
mission bandwidth.
Dynamic bandwidth management also for reception
For receiving bandwidth control, packets can be buffered and only belatedly
confirmed. Thus TCP/IP connections regulate themselves automatically on a
smaller bandwidth.
Each WAN interface is assigned a maximum reception bandwidth. This band-
width will be accordingly degraded by every QoS rule that guarantees a min-
imum bandwidth of reception on this interface.
̈ If the QoS rule has been defined connection-related, the reserved band-
width will be unblocked immediately after releasing the connection and
the maximum available bandwidth will increase accordingly on the WAN
interface.
̈ If the QoS rule has been defined globally, then the reserved bandwidth
will be unblocked only after the ending of the last connection.