Alcatel-Lucent 1643 AMS Applications And Planning Manual page 230

Ethernet Overview
Service level agreements
On the 1643 AM the responsibility for admission control is left to the operator. This
means there is no check that the Service Level Agreements on already existing
connections can be fulfilled, when a new user starts sending data from node A to B.
In this respect the notion of over-subscription factor is important. This is the factor by
which the calculated bandwidth, based on e.g. the traffic matrices of the operators
sharing a link, exceeds the physically available bandwidth. Although theoretically the
bandwidth can only be guaranteed for an over-subscription factor ≤ 1, in practice an
over-subscription factor of 5-10 can be used without giving problems. Due to the
effects of statistical multiplexing it is safe to "sell the bandwidth more than once". The
burstiness of the traffic from individual customers that share a common link makes this
possible. The Service Level Agreements give a quantification for the "statistics" of the
multiplexing.
Provisioning LAN and WAN ports details
The provisioning of the classifier and rate controller per flow is done only on the
ingress customer-role port (LAN port). On the network ports (WAN port), only the
scheduler for the egress queues is provisionable.
It is important that some of the QoS settings are provisioned consistently on all ports
throughout the whole customer's VPN domain. In the LAN-VPN (M-LAN) operation
mode, the rate controller mode (none, strict policing, oversubscription) must be
provisioned consistently (per virtual switch). The latter applies to the only. For the
scheduler, for each egress queue the mode = strict_priority/weighted_bandwidth and
corresponding weights (per virtual switch) must be provisioned consistently. This is
ensured by a background aging function of the system. The parameter will be enforced
to be set equally.
....................................................................................................................................................................................................................................
11-54 Alcatel-Lucent - Proprietary
See notice on first page
Quality of Service (QoS) overview
365-312-801R7.2
Issue 3, May 2007