Showing results for 
Search instead for 
Did you mean: 
Join Customer Connection to register!

Using WS-X6708-10GE with WS-F6700-DFC3C powered down

Hi All

I have installed a WS-X6708-10GE module into a 6509 chassis running a WS-SUP720-3BXL supervisor.  As per the cisco documentation, if I install this line card without powering down the switch, the DFC card will not be powered up (OIR is not supported between 3BXL SUP and 3C DFC card).  As far as I can tell, this will only limit the use of DFC with the module and it will revert to CFC mode to switch frames, is this correct?

Thanks in advance.

Matthew Blanshard
Cisco Employee

Hello Adam,

The 6708 will not be powered up until a reload is done on the chassis.  There is no revert to CFC mode when you have a DFC installed, you have either a CFC or DFC line card, they are different daughter cards.  So in short you will need to insert the card and then reboot in order for it to come up.


Thanks for the reply but i'm not sure that is the case as the module is up and the interfaces are configurable, it is only the DFC that has not been powered up?

Hello Adam,

the real issue is that DFC 3C does not support all the prefixes that PFC 3BXL can support.

if this chassis receives internet full table > 256,000 IP prefixes it will start to process switch for prefixes in excess causing main supervisor cpu to hit 100%

It happened to us when a WS-6708 with DFC 3CXL has been replaced by a WS-6708 with DFC 3C only.

The card had to be removed to make the system usable again!

So this setup is acceptable only if the system is not used for full BGP internet peering otherwise you need to get a DFC 3CXL.

Hope to help


Hi Giuesppe    This is not an Internet facing device so the prefix limitation is not a concen.  Do you know a way to have the module function without a reboot?

Hello Adam,

you said that the module is online and configurable and also in our case it was inline without reboot

you can check the state of sub module DFC  with show module output, I don't think you need to reload the system

I may be wrong but I saw  notes for RSP-720 not for sup720 3BXL (in case of RSP-720 the reload may be needed because it uses a PFC mode 3CXL and it has to revert to 3C only and so the need for the reload, there was another recent thread about this in that case the linecard was not powered)

Hope to help


Pavol Golis
Cisco Employee

"Mixing DFCs and PFCs also impacts on-line insertion and removal (OIR). If a line card with DFC3B is inserted into a switch with SUP720-3BXL, the line card does not power up.

In order to use DFC3A-equipped switching modules with a PFC3BXL or PFC3B, the DFC3A-equipped switching modules must be installed at boot up. In order to use DFC3B-equipped switching modules with a PFC3BXL, the DFC3B-equipped switching modules must be installed at boot up."