19216811.live030-300613 Rev A
111
August 2009
User Guide
VersaLink Wireless Gateway (Model 7500)
Enable QOS Services
Click this check box to enable or disable QOS Services. By default,
Enable QOS
Services
is enabled (checked).
WAN Upstream Rate
Displays the effective WAN upstream rate in kbps (kilobits per second). This value is
used to calculate Bandwidth Restrictions. The valid range is between 100 (100 kbps)
and 100000 (100 mbps). Leave blank to use the automatically determined rate.
Turbo TCP Enabled
Click this check box to enable or disable Turbo TCP. By default,
Turbo TCP
Enabled
is disabled (unchecked).
IP Fragmentation Enabled
Click this check box to enable or disable IP Fragmentation. IP Fragmentation
fragments (breaks apart) large, fragmentable, low-priority packets to reduce latency
for higher-priority traffic. For large, non-fragmentable, low-priority packets, the
Gateway sends back an ICMP message specifying the fragment size as the link MTU.
When enabled, and packets larger than 1500 bytes total are received by the Gateway,
these packets will be fragmented. By default,
IP Fragmentation Enabled
is disabled
(unchecked).
Note: Later versions of the Windows OS may not honor this ICMP message for any
except the very largest fragment size. If this occurs, then many Web operations may
not work if a voice call is in progress.
IP Fragmentation Size
Click this drop-down menu to select the size (bytes) that the packets will be
fragmented into. The available numbers consider ATM cell size boundaries, ATM
Ethernet encapsulation, IP headers, and PPPoE encapsulation: 100, 148, 244, 292,
340, 388, or 436 bytes.
Class of Service
Displays the supported classes of service (ordered from lowest priority to highest
priority).
•
Network Control (NC)
•
Expedited Forwarding (EF)
•
Assured Forwarding (AF4)
•
Assured Forwarding (AF3)
•
Assured Forwarding (AF2)
•
Assured Forwarding (AF1)
•
Best Effort (BE)
Peak Info Rate
Displays the maximum allowed rate for this Class of Service, expressed as a
percentage of the WAN rate. Packets will be discarded if the offered rate exceeds this
value. The Peak Information Rate can be used to prevent higher priority traffic from
using all available bandwidth. No limit is necessary for the lowest priority traffic
(BE). No limit is necessary for the lowest priority traffic (BE). A value of zero causes
the modem to drop all packets for this class of service.
Committed Info Rate
Displays the committed rate (for Assured Forwarding classes), expressed as a
percentage of the WAN rate. Packets may have the drop priority of the DSCP
increased if the offered rate exceeds this value. Note that this only occurs for non-
zero committed rates (i.e., a value of zero turns off the committed filter).
Enable QOS Filter Rules
Click this check box to enable or disable Enable QOS Filter Rules, allowing
remarking of the packet DiffServ CodePoint (DSCP). Various filtering (matching)
options can be set to determine which packets should be re-marked. Changing the
DSCP of a packet changes its priority for transmission. QOS Services does not have
to be enabled for filter rules to be activated. By default,
Enable QOS Filter Rules
is
enabled (checked).
Edit QOS Filter Rules
Click this button to edit QOS Filter Rules using the
QoS Filters
screen. Refer to
section 14.4.6.1, “QoS Filters—Edit Filter Rules.”