Lancom Systems LCOS 3.50 - Manual (Page 172)

LANCOM Reference Manual LCOS 3.50 ̈ Chapter 9: Quality of Service
172
Quality of
Service
9.2.2 Limited maximum bandwidths
Hereby you limit e.g. the entire or connection-related maximum bandwidth
for server accesses.
An example:
You operate both a Web server and a local network on a shared Internet
access.
To prevent that your productive network (LAN) is paralyzed by many Internet
accesses to your Web server, all server accesses are limited to half of the avail-
able bandwidth. Furthermore, in order to guarantee that your server services
are available equally to many users at the same time, a certain maximum
bandwidth per each server connection is set.
Combination possible
Minimum and maximum bandwidths can be used together in combination.
Thus the available bandwidth can be distributed accordingly depending on
your requirements, e.g. on certain user groups or applications.
9.3 The queue concept
9.3.1 Queues in transmission direction
Quality of Service requirements are realized in LCOS by using different queues
for the data packets. For the transmission side, the following queues are uti-
lized:
̈ Urgent queue I
This queue is always processed at first before all others. The following
data packets are handled here:
୴ Packets with ToS “Low Delay“
୴ Packets with DiffServ “Expedited Forwarding“
୴ All packets that have been assigned a certain minimum bandwidth, as
long as the guaranteed minimum bandwidth is not exceeded.
୴ TCP control packets can be likewise dispatched by this queue prefer-
entially (see ’SYN/ACK speedup’
→ page 73).
̈ Urgent queue II
This is for all packets that have been assigned a guaranteed minimum
bandwidth, but whose connection has exceeded this minimum band-
width.