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Cisco Aironet 1520, 1130, 1240 Series Wireless Mesh Access Points, Design and Deployment Guide, Release 6.0
OL-20213-01
Connecting the Cisco 1520 Series Mesh Access Point to Your Network
Bridging Packets from and to a LAN
Packets received from a station on a LAN are not modified in any way. There is no override value for the
LAN priority. Therefore, in bridging mode the LAN must be properly secured. The only protection
offered to the mesh backhaul is that non-CAPWAP control frames that map to the platinum queue are
demoted to the gold queue.
Packets are transmitted to the LAN precisely as they are received on the Ethernet ingress at entry to the
mesh.
The only way to integrate QoS between Ethernet ports on AP1520 and 802.11a is by tagging Ethernet
packets with DSCP. AP1520s will take the Ethernet packet with DSCP and place it in the appropriate
802.11e queue.
AP1520s do not tag DSCP itself:
•
On the ingress port, the 1520 sees a DSCP tag and encapsulates the Ethernet frame and apply the
corresponding 802.11e priority.
•
On the egress port, the AP1520 decapsulates the Ethernet frame and places it on the wire with an
untouched DSCP field.
Ethernet devices such as video cameras, should have the capability to mark the bits with DSCP value to
take advantage of QoS.
Note
QoS only is relevant when there is congestion on the network.
Guidelines For Using Voice On The Mesh Network
•
Voice is only supported on indoor mesh access points, 1130 and 1240.
•
When voice is operating on a mesh network, calls must not traverse more than two hops.
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Each sector must be configured to require no more than two hops for voice.
•
RF considerations for voice networks:
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Coverage hole of 2 to 10 percent
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Cell coverage overlap of 15 to 20 percent
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RSSI and SNR values that are at least 15 dB higher than data requirements. For example, Cisco
recommends an RSSI of -67 dBm for an 11 or 12 Mb/s link and an SNR of no more than 25 dB.
Likewise, an RSSI of -56 dBm for a 56 Mb/s link is recommended with an SNR of no more than
40 dB.
–
An RSSI of -62 dBm is recommended on a 24 Mb/s 802.11a backhaul when universal access is
configured and client traffic is present.
–
Packet error rate (PER) must be configured for a value of one percent or less.
–
Channel with the lowest utilization (CU) must be used. Check the CU when no traffic is running.
–
Radio resource manager (RRM) can be used to implement the recommended RSSI, PER, CU,
cell coverage and coverage hole settings on the 802.11 b/g radio. RRM is not supported on the
802.11a radio.
•
On the
802.11a
or
802.11b/g/n >
Global
parameters window:
–
Enable dynamic target power control (DTPC)
–
Disable all data rates less than 11 Mb/s