D-Link Unified Access System
Software User Manual
02/15/2011
Page 158
Document 34CS3000-SWUM104-D10
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to update the switch with the values on the screen. If you want the switch to retain the new values across a
power cycle you must perform a save.
Enabling SNMP Traps
If you use Simple Network Management Protocol (SNMP) to manage the D-Link Unified Switch, you can configure the SNMP
agent on the switch to send traps to the SNMP manager on your network from the
Administration > Advanced
Configuration > Global > SNMP Traps
tab.
Figure 75: SNMP Trap Configuration
Tunnel IP MTU Size
Sets the maximum size of the IP packet handled by the network. The MTU is enforced only
on tunneled VAPs. Select one of the following values:
• 1500:
Maps the tunneled IP frame size to 1518 bytes (untagged) and 1522 bytes (tagged).
Use this setting if your network does not support jumbo frames. Using 1500 as the Tunnel IP
MTU size forces the D-Link Unified Access System to limit its maximum message size to
1518/1522 bytes. This setting directs the wireless system to mitigate the problem of
oversized frames by enabling the MTU discovery protocol and limiting the maximum segment
size in TCP connection setup messages.
• 1520:
Maps the tunneled IP frame size to 1538 bytes (untagged) and 1542 bytes (tagged).
Use this setting if your network supports jumbo frames and you have configured the physical
ports between the switch and the APs to support 1538/1542 byte packets.
IP Packets that use the L3 tunnel have an extra 20 bytes in the header for encapsulation. This
means that wireless clients configured with a 1500 byte IP MTU size may exceed the
maximum MTU size of the existing network infrastructure if it is set up to switch and route 1518
(1522-tagged) byte frames.
Setting the Network MTU Size to 1500 or 1520 does not affect physical port MTU size. The
physical ports on the switch and the rest of the network devices must be configured with the
appropriate MTU size.
Note:
If the AP is not connected directly to the wireless switch and the Tunnel IP MTU Size
is set to 1520, any Ethernet segments in the path between the AP and the wireless switch
must support jumbo frames and be configured for jumbo frames.
AP Client QoS
Select this option to apply access control lists (ACLs) and differentiated service (DiffServ)
policies to the AP.
Table 58: General Global Configurations
Field
Description
