Redundant Power Supplies
The Cisco Catalyst 6500 and 4500R platforms can accept two power supply modules in a single chassis. The power supplies must be identical, having the same power input and maximum power output ratings. The switch can be configured to operate in one of two possible power modes:
■ Combined mode—Both power supplies work together to share the total power load for all modules that are installed in the switch chassis. The total load required can exceed the maximum power output rating of one power supply but must not exceed the sum of both supplies.
Combined mode is useful for meeting large power requirements if many switch modules are installed or if Power over Ethernet (PoE) is being used to supply power to end devices such as IP telephones. However, combined mode does not provide power redundancy. If one power supply fails, the switch powers down some of its modules until the required power load can be met by the one functioning power supply.
■ Redundant mode—Each of the installed power supplies can supply the total power load that is required by the whole switch chassis. If one power supply fails, the other immediately can carry the total power load of the switch without powering down any modules.
By default, a switch is configured for redundant mode. If two power supplies are installed and functioning, they are managed as redundant replacements for each other. Both supplies are enabled and active, as if they were both supplying power. In fact, you probably won't be able to tell which supply is actually powering the switch until one of them is turned off or fails.
You can display the current power configuration and status of a switch with the following command:
Switch# show power [redundancy-mode | status | available | used | total]
If you don't use any of the optional keywords, the resulting output yields all information about the system power. For instance, notice that the switch in Example 13-11 is in redundant mode and that both power supplies are operational.
Example 13-11 Verifying Switch Redundant Mode and Power Supply Operational Status
|
Switch# show power |
||||||
|
system power redundancy |
mode = redundant |
|||||
|
system power total = |
1153.32 Watts |
(27.46 |
Amps @ |
42V) |
||
|
system power used = |
693.42 Watts |
(16.51 |
Amps @ |
42V) |
||
|
system power available |
459.90 Watts |
(10.95 |
Amps @ |
42V) |
||
|
Power-Capacity |
PS-Fan |
Output |
Oper |
|||
|
PS |
Type |
Watts A @42V |
Status |
Status |
State |
|
|
1 |
WS-CAC-1300W |
1153.32 27.46 |
OK |
OK |
on |
|
|
2 |
WS-CAC-1300W |
1153.32 27.46 |
OK |
OK |
on |
|
|
Pwr-Requested |
Pwr-Allocated |
Admin |
Oper |
|||
|
Slot |
Card-Type |
Watts A @42V |
Watts |
A @42V State |
State |
|
|
1 |
WS-X6K-SUP2-2GE |
145.32 3.46 |
145.32 3.46 |
on |
on |
|
|
2 |
145.32 3.46 |
|||||
|
3 |
WS-X6348-RJ45 |
100.38 2.39 |
100.38 2.39 |
on |
on |
|
|
4 |
WS-X6516-GBIC |
142.80 3.40 |
142.80 |
3.40 |
on |
on |
|
5 |
WS-C6500-SFM |
117.18 2.79 |
117.18 |
2.79 |
on |
on |
|
Switch# |
||||||
The show power command also displays information about the status of each switch module, the amount of power it has requested to receive, and the amount of power it is actually being budgeted. Most switch modules have a fixed power requirement, so the power requested and allocated values are equal.
One important exception is any switch module that supplies inline power or PoE to end devices. These end devices can request a power budget when they initialize and can request a different budget at any later time. Cisco IP telephones and wireless access points are good examples of this. Power requests are handled through Cisco Discovery Protocol (CDP) exchanges between the device and the switch. You can display the current power status of inline power switch ports with the show power inline command, as demonstrated in Example 13-12.
Example 13-12 Verifying Inline Power Switch Port Status
Switch# show power inline
Interface Admin Oper Power Device
(Watts)
Switch# show power inline
Interface Admin Oper Power Device
(Watts)
|
Fa3/1 |
auto |
off |
o |
n/a |
||||
|
Fa3/2 |
auto |
on |
6 |
2 |
cisco |
AIR |
-AP1230B-A |
|
|
Fa3/3 |
auto |
on |
6 |
2 |
cisco |
AIR |
-AP1230B-A |
|
|
Fa3/4 |
auto |
on |
5 |
6 |
Cisco |
IP |
Phone |
79o5 |
|
Fa3/5 |
auto |
on |
5 |
6 |
Cisco |
IP |
Phone |
79o5 |
|
Fa3/6 |
auto |
on |
6 |
3 |
Cisco |
IP |
Phone |
794o |
|
Fa3/7 |
auto |
on |
6 |
3 |
Cisco |
IP |
Phone |
794o |
|
Fa3/8 |
auto |
on |
6 |
3 |
Cisco |
IP |
Phone |
794o |
|
Fa3/9 |
auto |
off |
o |
n/a |
||||
|
Fa3/10 |
auto |
on |
6 |
3 |
Cisco |
IP |
Phone |
7912 |
|
Fa3/11 |
auto |
off |
o |
n/a |
||||
|
Fa3/12 |
auto |
on |
6 |
3 |
Cisco |
IP |
Phone |
794o |
|
Fa3/13 |
auto |
on |
6 |
3 |
Cisco |
IP |
Phone |
794o |
|
Fa3/14 |
auto |
on |
6 |
3 |
Cisco |
IP |
Phone |
794o |
|
[output |
omitted] |
|||||||
You can change the power supply mode by using the following command:
Switch(config)# power redundancy-mode {redundant I combined}
You also can control the power that is being supplied to a switch module. For example, if you want to remove a module for repair or relocation, you can disable its power before it is pulled out of the chassis. Use the following command to control the power to the module in chassis slot number slot:
Switch(config)# [no] power enable module slot Without the no keyword, the module is powered on; include the no keyword to remove power from the module.
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