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Switch fabric modules and distributed forwrding cards !!!!!

Unanswered Question
Oct 23rd, 2003
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Hello all,

I am looking to purchase a 6506 catalyst switch with 2 supervisor engines, a 10/100/1000mbps line card and a fiber line card.

I have been informed by a supplier that we also need :

1. switch fabric module

2. distributed forwarding card

What are these and is this true? Can anyone point me to an area that gives definitive answers on this as i am getting v. confused!!!

if i do need these modules also then i have filled all module slots on the 6506 straight away, which doesnt make it a very modular switch in my eyes!!!

many thanks


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rmcarthur Thu, 10/23/2003 - 01:25
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You may or may not require an SFM and DFC. It depends on your application and line cards.

The DFC is a daughter card for supported linecards (most cef256 cards) so you won't lose a slot to it.

The switch fabric modules deliver an increase in available system bandwidth from the existing 32Gbps to 256Gbps. The Switch Fabric Module allows 30 Mpps of forwarding performance on Supervisor Engine 2 and up to 210 Mpps of distributed forwarding performance. The dfc (WS-F6K-DFC) is required to be installed on the line cards to deliver up to 210 Mpps of distributed forwarding.


r.dufton Thu, 10/23/2003 - 02:30
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many thanks for that reply,

if i can summarise this means that i dont need either to get a switch up and running if i am using 1*10/100/1000mbps line card and 1*8*port gbic module?

the sfm is simply an add on to boost performance?

the dfc is also not neccessary? what is meant by a daughter card and how does this connect to the switch if not through a module slot ?


rmcarthur Thu, 10/23/2003 - 03:15
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Again, it depends. If you have any fabric only linecards, ws-x6816 for eg, then you will need an SFM as these cards have no connection to the classic bus. If you were using a ws-x6516 however, you could use that either with or without an SFM as this card has connections to both the classic bus and the switch fabric.

The DFC mounts directly onto the linecard so does not require a slot.

If you are using cards that begin with WS-X68xx in the chassis then you will require an SFM.

The fabric-only line cards have the DFC embedded in the system.

It is optional for the fabric enabled cards, WS-x65xx etc.

See the link for details



r.dufton Thu, 10/23/2003 - 03:45
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cheers mate this is very helpful advice.

the rj-45 10/100/100mbps 16 port is a ws-65xx and can connect directly to the bus.

the 8 port gbic module however is a ws-6816-gbic but seems to offer a version with fabric enabled and a version without fabric enabled. The fabric enabled version indicates that it can connect direct to the bus but for some reason they both share the same product code. Not sure why that is so i will have to be careful when ordering,


r.dufton Thu, 10/23/2003 - 04:41
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Further to this,

I think there may be a typo on the cisco site. It definately says that there is 2 versions of the 6816 available. One enabled and one not enabled. I think one of these should read 6516. Thanks to your links I have finally got to the bottom of this.

I am going for the 65xx versions of both.

Again, many thanks



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