Cisco Cisco 5508 Wireless Controller Libro blanco
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White Paper: Mobile Access Indoor Wireless Solution and Cisco WLANs
Co-existence of Signaling on the CAT-5e/6 Cable
Co-existence of Signaling on the CAT-5e/6 Cable
On the Ethernet port signaling side of the Mobile Access VCU the cellular traffic is transmitted onto the
cable at a different frequency than the frequency used for the LAN packets to and from the Aironet AP
to prevent interference with each other. The VCU and VAP devices transmit analog radio signals over
the CAT-5e/6 cable by down-shifting the cellular frequencies to intermediate frequencies. Since the
frequency range used of cellular traffic is different from Ethernet traffic; there is no cross talk or
harmonic inference between the two technologies. The cellular frequencies are 140-220 MHz, while the
Ethernet spectrum is 0-125 MHz. The MobileAccessVE device performance is not influenced by the
presence or absence of Cisco switches or APs. The MobileAccessVE devices that share the same cable
run as the Cisco devices are not influenced by the power state(on/off) of the Cisco devices. The
MobileAccessVE devices are passive with concern to Ethernet connectivity. The RJ-45 ports on the VCU
are strictly pass-through. They are not programmable in the sense of switch ports on a Cisco switch.
cable at a different frequency than the frequency used for the LAN packets to and from the Aironet AP
to prevent interference with each other. The VCU and VAP devices transmit analog radio signals over
the CAT-5e/6 cable by down-shifting the cellular frequencies to intermediate frequencies. Since the
frequency range used of cellular traffic is different from Ethernet traffic; there is no cross talk or
harmonic inference between the two technologies. The cellular frequencies are 140-220 MHz, while the
Ethernet spectrum is 0-125 MHz. The MobileAccessVE device performance is not influenced by the
presence or absence of Cisco switches or APs. The MobileAccessVE devices that share the same cable
run as the Cisco devices are not influenced by the power state(on/off) of the Cisco devices. The
MobileAccessVE devices are passive with concern to Ethernet connectivity. The RJ-45 ports on the VCU
are strictly pass-through. They are not programmable in the sense of switch ports on a Cisco switch.
Co-existence of PoE on the CAT-5e/6 Cable
The amount of power that a switch provides at the power sourcing port depends on the switch or line
card of the switch. It also depends on the model of the switch or line card and the power supplies of the
switch. Cisco switches then negotiate the amount of power to provide to the endpoint using the Cisco
Discovery Protocol (CDP). A Cisco switch provides power to the Aironet AP. The VCU provides power
to the Mobile Access VAP. The ability to provide power to Aironet AP from the CAT-5e/6 cable that is
also powering the VAP is done using different wire pairing within the CAT-5e/6 cable for each AP.
CAT-5e/6 cable has four pairs of wire. The Cisco switch provides power on pairs 1-2 and 3-6 for the
Aironet AP per 802.af type A standards. The MobileAccessVE provides power separately for the VAP
on pairs 4-5 and 7-8. Therefore, Aironet AP and the VAP have unique power sources. The
MobileAccessVE and VAP pass the power from the Cisco switch through to the AP passively. This
separate, independent supply of power on the CAT-5e/6 cables provides the VAP full service
functionality and the Aironet AP full 802.11n performance.
card of the switch. It also depends on the model of the switch or line card and the power supplies of the
switch. Cisco switches then negotiate the amount of power to provide to the endpoint using the Cisco
Discovery Protocol (CDP). A Cisco switch provides power to the Aironet AP. The VCU provides power
to the Mobile Access VAP. The ability to provide power to Aironet AP from the CAT-5e/6 cable that is
also powering the VAP is done using different wire pairing within the CAT-5e/6 cable for each AP.
CAT-5e/6 cable has four pairs of wire. The Cisco switch provides power on pairs 1-2 and 3-6 for the
Aironet AP per 802.af type A standards. The MobileAccessVE provides power separately for the VAP
on pairs 4-5 and 7-8. Therefore, Aironet AP and the VAP have unique power sources. The
MobileAccessVE and VAP pass the power from the Cisco switch through to the AP passively. This
separate, independent supply of power on the CAT-5e/6 cables provides the VAP full service
functionality and the Aironet AP full 802.11n performance.
Testing to Identify Co-existence Issues
Cisco engineers tested the following items to identify co-existence issues:
•
Maximum Ethernet Cable Length
•
Ethernet compliance per 802.3 specifications
•
Product Safety and Compliance
•
Cisco device Interoperability
Maximum Cable Length
The highest length of CAT-5e/6 cable that is recommended for a gigabit Ethernet run is a total of 100
meters. It is recommended that only CAT-5e or better be used in any portion of the run. A run is defined
as the total CAT-5e/6 cable connections between the PoE switch port to the final Ethernet client device.
All connections to MobileAccessVE Controller (VCU) and the MobileAccessVE Access Pod (VAP) add
into that total run length. This is because to the gigabit Ethernet signals, the VCU and VAP are passive,
pass-through devices. Therefore, in considering the maximum run length, there will be a minimum of
meters. It is recommended that only CAT-5e or better be used in any portion of the run. A run is defined
as the total CAT-5e/6 cable connections between the PoE switch port to the final Ethernet client device.
All connections to MobileAccessVE Controller (VCU) and the MobileAccessVE Access Pod (VAP) add
into that total run length. This is because to the gigabit Ethernet signals, the VCU and VAP are passive,
pass-through devices. Therefore, in considering the maximum run length, there will be a minimum of