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Appendix A
Specifications
Figure A-5
Examine the sequence of colored wires to determine the type of cable, as follows:
•
•
You can identify a crossover cable by comparing the two modular ends of the cable. Holding the cables
in your hand, side-by-side, with the tab at the back, the wire connected to the pin on the outside of the
left connector (pin 1) should be the same color as the pin on the outside of the right connector (pin 8).
Table A-12
Table A-12
Cable
Crossover
Crossover
Straight-through
Gigabit Ethernet Flow Control Information
Flow control is not configurable. The information in this section explains some of the parameters of flow
control.
GE port 0/3:
•
•
GE ports 0/0, 0/1, and 0/2:
These interfaces function the same as above with the exception that there will never be a pause request
transmitted regardless of mode.
OL-11364-04
Identifying a Crossover or Straight-Through Cable
Straight-through—The colored wires are in the same sequence at both ends of the cable.
Crossover—The first (far left) colored wire at one end of the cable is the third colored wire at the
other end of the cable.
provides information about asynchronous device cabling options.
Asynchronous Device Cabling Options
When the Cisco 7201 GE 0/3 port is set to no negotiation auto, it does not advertise anything in
regard to flow control. The Cisco 7201 GE 0/3 port responds to pause frames if the other side makes
the request, but will not send pause frames.
When the Cisco 7201 GE 0/3 port is set to negotiation auto, flow control is enabled, which means
the peer accepts symmetrical or asymmetical flow control, and sends pause frames. If the peer does
not accept flow control requests, the Cisco 7201 router does not send pause frames. (The Cisco 7201
router always accepts pause frames, whether in fixed mode or auto mode.)
Adapter
RJ-45-to-DB-25M
RJ-45-to-DB-9M
RJ-45-to-DB-25F
Cisco 7201 Installation and Configuration Guide
Gigabit Ethernet Flow Control Information
End Device
Terminal or DTE
Terminal or DTE
Modem or DCE
A-9
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