CAT6500 line card power consumption

[pete.pmp]

Hi, I would like to ask if it is normal behavior of the CAT6500 switch to have 2 same line cards with different power consumption. I experience this situation with line card WS-X6724-SFP.

Output of my HW configuration is as below:

Switch module HW configuration::

Mod Ports Card Type                              Model             

--- ----- -------------------------------------- ------------------

  2   24  CEF720 24 port 1000mb SFP              WS-X6724-SFP      

  3   40  DCEF2T 8 port 40GE / 32 port 10GE      C6800-32P10G      

  4   40  DCEF2T 8 port 40GE / 32 port 10GE      C6800-32P10G      

  5    5  Supervisor Engine 2T 10GE w/ CTS (Acti VS-SUP2T-10G      

  6   24  CEF720 24 port 1000mb SFP              WS-X6724-SFP      

  7   48  48-port 100FX SFP Ethernet Module      WS-X6148-FE-SFP  

Switch power consumption output::

system power redundancy mode = redundant

system power total =     2771.16 Watts (65.98 Amps @ 42V)

system power used =      2478.84 Watts (59.02 Amps @ 42V)

system power available =  292.32 Watts ( 6.96 Amps @ 42V)

                        Power-Capacity PS-Fan Output Oper

PS   Type               Watts   A @42V Status Status State

---- ------------------ ------- ------ ------ ------ -----

1    WS-CAC-3000W       2771.16 65.98  OK     OK     on

2    WS-CAC-3000W       2771.16 65.98  OK     OK     on

                        Pwr-Allocated  Oper

Fan  Type               Watts   A @42V State

---- ------------------ ------- ------ -----

1    WS-C6509-E-FAN      210.00  5.00  OK

                        Pwr-Requested  Pwr-Allocated  Admin Oper

Slot Card-Type          Watts   A @42V Watts   A @42V State State

---- ------------------ ------- ------ ------- ------ ----- -----

2    WS-X6724-SFP        125.16  2.98   125.16  2.98  on    on

3    C6800-32P10G        588.00 14.00   588.00 14.00  on    on

4    C6800-32P10G        588.00 14.00   588.00 14.00  on    on

5    VS-SUP2T-10G        435.54 10.37   435.54 10.37  on    on

6    WS-X6724-SFP        435.54 10.37   435.54 10.37  on    on

7    WS-X6148-FE-SFP      96.60  2.30    96.60  2.30  on    on

system auxiliary power mode = off

system auxiliary power redundancy operationally = non-redundant

system primary connector power limit =   10920.00 Watts (260.00 Amps @ 42V)

system auxiliary connector power limit = 10500.00 Watts (250.00 Amps @ 42V)

system primary power used =              2478.84 Watts (59.02 Amps @ 42V)

system auxiliary power used =            0 Watt

May I assume it as some kind of bug, or HW fault?

[Rich Uline]

Pet86,

If you issue the 'show module' command, there should be a section below the main output which lists daughterboards. I suspect the daughterboards are not the same for slots 2 and 6. I suspect you have a CFC in slot 2 and a DFC in slot 6. See this article for an explanation of those.

[pete.pmp]

Hi Rich, thank you for fast reply.

I issued show module command and found out that both linecards have the same CFC as you can see below. Cards number 2 & 6.

Any other idea?

Mod Sub-Module Model Hw Status
---- --------------------------- ------------------ ------- -------
2 Centralized Forwarding Card WS-F6700-CFC 2.0 Ok
3 Distributed Forwarding Card C6800-DFC 1.2 Ok
3 Distributed Forwarding Card C6800-DFC 1.1 Ok
4 Distributed Forwarding Card C6800-DFC 1.2 Ok
4 Distributed Forwarding Card C6800-DFC 1.1 Ok
5 Policy Feature Card 4 VS-F6K-PFC4 3.0 Ok
5 CPU Daughterboard VS-F6K-MSFC5 3.1 Ok
6 Centralized Forwarding Card WS-F6700-CFC 4.1 Ok

[Rich Uline · Accepted solution]

Pet86,

That is strange. I have another idea, though. The 6509 backplane connectors are a little different in slots 5 and 6 as these slots must accommodate the supervisors. I wonder if the physical characteristics of the slot are influencing how much power is allocated. I'm curious if the power reading would be different if the card was moved from slot 6 to another slot (slot 1, for example). But, obviously, this is something that shouldn't be done if the device is in production.

[pete.pmp]

Fairly good idea, thanks.

Luckily, we have one chassis and some of mentioned line cards so we could test tomorrow. I will let you know.

[pete.pmp]

Hi Rich,

We performed simple test with CAT6500 chassis. We used chassis 6506-E with VS-SUP2T-10G supervisor and different combination of available line cards.

First test was performed with supervisor engine without line cards. You can see show power outcome below. Interesting thing I was not aware of is that power for slot 6 is allocated regardless of module 6 is installed or not.

Router>sh power
system power redundancy mode = redundant
system power redundancy operationally = non-redundant
system power total = 2771.16 Watts (65.98 Amps @ 42V)
system power used = 1011.78 Watts (24.09 Amps @ 42V)
system power available = 1759.38 Watts (41.89 Amps @ 42V)
Power-Capacity PS-Fan Output Oper
PS Type Watts A @42V Status Status State
---- ------------------ ------- ------ ------ ------ -----
1 WS-CAC-3000W 2771.16 65.98 - - off
2 WS-CAC-3000W 2771.16 65.98 OK OK on
Pwr-Allocated Oper
Fan Type Watts A @42V State
---- ------------------ ------- ------ -----
1 WS-C6506-E-FAN 140.70 3.35 OK

Pwr-Requested Pwr-Allocated Admin Oper
Slot Card-Type Watts A @42V Watts A @42V State State
---- ------------------ ------- ------ ------- ------ ----- -----
5 VS-SUP2T-10G 435.54 10.37 435.54 10.37 on on
6 (Redundant Sup) - - 435.54 10.37 - -

We found out, that when you put line card WS-X6724-SFP to any chassis slot except 5 or 6 (allocated primarily for supervisor engine), allocated power is almost as Cisco says (Cisco doc says 99W, reality says 125W). 

When you put it to slot allocated for supervisor engine (5 or 6), allocated power is same or higher value as for supervisor engine.

Pwr-Requested Pwr-Allocated Admin Oper
Slot Card-Type Watts A @42V Watts A @42V State State
---- ------------------ ------- ------ ------- ------ ----- -----

6    WS-X6724-SFP        435.54 10.37   435.54 10.37  on    on

Pwr-Requested Pwr-Allocated Admin Oper
Slot Card-Type Watts A @42V Watts A @42V State State
---- ------------------ ------- ------ ------- ------ ----- -----

6    C6800-32P10G        588.00 14.00   588.00 14.00  on    on

Official Cisco doc states that power consumtion of line cards and SUP2t are:

C6800-32P10G  588.00W

WS-X6724-SFP 99.66W

VS-SUP2T-10G 285W

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/hardware/Chassis_Installation/Cat6500/6500_ins/0dpwrht.html

[Joseph W. Doherty]

Different HW revs though?

Also, card's power draw might be also determined by how many ports are actually active. How do those two card compare regarding active ports?

[Rich Uline]

Joseph,

Unless there is a bug, I expect a higher hardware revision number to consume less power. While a card may actually use varying amounts of power depending on the number of active interfaces, it is my experience that the 6500 reserves the full amount of power regardless. Even if that were not the case, Cisco SFPs use somewhere in the neighborhood of 1 watt each. A fully populated vs. not fully populated card would, therefore, have a difference of 24 watts which doesn't explain the observed difference of 310 watts. Finally, I think it's very suspicious that the 6500 has reserved the exact same amount of power for the SFP line card as it did the supervisor.

[pete.pmp]

HI Joseph, it does not make sense to me.

Why would line card with older HW version take less power? I assume new products should take less power, but you never know.

Ok, back to number of active ports. It is almost the same. Card seated in slot 2 has little bit more active ports (+5) than card seated in slot 6 with less power consumption.

[Joseph W. Doherty]

I think Rich's is probably the most likely correct answer, barring a bug. I.e. the chassis sets asides the power needed for a sup.