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New Member

WS-X6724-SFP module

Can someone help educated me on what the primary use of this module is? I'm not clear on the difference between centralized forwarding and local forwarding. I have one in each of my two 6513's connecting them together and would like to use the unused gigabit ports for my servers.

Is it a card I could use to connect hosts to, such as servers?

Any input would be appreciated.

Steve

12 REPLIES
VIP Super Bronze

WS-X6724-SFP module

Is it a card I could use to connect hosts to, such as servers?

Sure, you can use the ports for anything you want as long as the end devices or switches support fiber.

X6724-SFP takes LC type connector.  It is basically a 1Gig fiber blade.

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/product_data_sheet0900aecd801459a7.html

HTH

Hall of Fame Super Bronze

WS-X6724-SFP module

Reza,

Not just Fiber. You can get Copper SFPs.

VIP Super Bronze

WS-X6724-SFP module

Yes Sir.  You are correct.  You can use copper SFP with copper cable distance limitation.

Reza

Hall of Fame Super Bronze

WS-X6724-SFP module

Steve,

6724 is a CEF720 Module. The line card in this mode supports a connection  into the 32-Gbps shared bus and the switch fabric: these line cards will  use the switch fabric on the Supervisor Engine720 for data switching.

On a DFC based module such as 6708, its only requires the  switch fabric to be present to switch packets. They connect into the  switch fabric channels at 20Gbps.

For server connection, we often recommend DFC based modules for higher performance.

New Member

WS-X6724-SFP module

Thank you for the info, very helpful.

One more question, would I see any performance boost connected to this module over a typical WS-X6148-GE-TX gig blade?

VIP Super Bronze

WS-X6724-SFP module

Steve,

The WS-X6148-GE-TX is 10/100/1000 vs X6724-SFP is Gig only.  So, if your end devices are Gig, then using copper of fiber should not make any different in performance.

HTH

Super Bronze

Re: WS-X6724-SFP module

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

One more question, would I see any performance boost connected to this module over a typical WS-X6148-GE-TX gig blade? 

You may.  The 6148-GE-TX has only 1 MB per 8 ports.  The 6148A-GE-TX is enhanced, with 2.67 MB per port, additional queuing and jumbo frame support.  The 6724-SFP actually has less egress buffers (1.17 MB) but it has 20 Gbps fabric while the 6148 cards are classic bus only (16 Gbps [duplex] shared bus across whole chassis, and sup limited to 15 Mpps.)  I.e. Cisco positions the 6148 as a wiring closet cards, the 6700 series for high performance.

Super Bronze

Re: WS-X6724-SFP module

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

6724 is a CEF720 Module. The line card in this mode supports a connection  into the 32-Gbps shared bus and the switch fabric: these line cards will  use the switch fabric on the Supervisor Engine720 for data switching.

I believe any CEF720 line card is fabric only; single 20 Gbps for the 6724-SFP.

On a DFC based module such as 6708, its only requires the  switch fabric to be present to switch packets. They connect into the  switch fabric channels at 20Gbps.

Two notes.  6724-SFP can take a DFC as an option.  Usage of fabric doesn't require DFC.  (DFC can boost overall forwarding capacity, as ingress to the card is switched/forwarded by the local DFC; i.e. doesn't need to use the main sup.  Sup720 offers up to 30 Mpps, for whole chassis, independent of packet size if using compact mode.  DFC3 provides up to 48 Mpps, for just the line card.)

Hall of Fame Super Bronze

WS-X6724-SFP module

CEF720 will use the shared bus for lookup

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/prod_white_paper0900aecd80673385.html

Yes, 6724 as well as the 6748 will make use of an optional DFC and they become dCEF720 modules once this option is added increasing their performance.

However, I made sure to use a module such as 6708 where the DFC isn't optional to make my point.

Usage of Fabric does not require a DFC but the module needs to perform lookup using the share bus hence there is a minimal performance impact.

Super Bronze

Re: WS-X6724-SFP module

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

CEF720 will use the shared bus for lookup 

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/prod_white_paper0900aecd80673385.html

Agreed (see Figure 24 in your reference [also for CEF256]), although dCEF should not (see Figure 25 in your reference).

Yes, 6724 as well as the 6748 will make use of an optional DFC and they become dCEF720 modules once this option is added increasing their performance.

Usage of Fabric does not require a DFC but the module needs to perform lookup using the share bus hence there is a minimal performance impact.

". . . modules needs to perform lookup using the share bus . . ."?  You mean a CEF line card or the DFC module?  Agreed if you mean the former, if the latter, DFC should be doing lookup locally.

I also agree using the main sup vs. a DFC for the lookup may incur some performance impact (probably increased latency, but if so, probably also at the microsecond level), but assuming the main sup isn't overload, it's probably very, very minimal impact.  In other words, just using DFC enabled CEF line cards might offer unnoticeable improved performance unless the main sup is overloaded.

However, I made sure to use a module such as 6708 where the DFC isn't optional to make my point.

As an aside, the 6708 is an interesting card, as you note, it comes standard with a DFC.  Only Cisco could really tell us why they made the DFC standard with the 6708, but my guess is 1) because the card oversubscribes the fabric (2:1), believe the DFC allows same line card port-to-port traffic, which avoids the potential bottleneck to the main fabric, and 2) when the card card came out, you were most likely going to use it for infrastructure links, not host links, and the former might be "busier".  If so, and if you start to load up a core/distribution 6509 with these, the overall aggregate bandwidth could easily outpace the capacity of the sup720, so off-loading packet forwarding to the line card may become critical.  (NB: BTW, in theory, the 48 Mpps offered by the DFC4 only guarantees about 32 Gbps [i.e. for min size Ethernet].)

PS:

To the original poster, if you mix fabric only cards with classic bus cards in the same chassis (e.g. your 6148 and your 6724), the cards might not directly transfer data between them (fabric only cards put their data on the fabric, which a classic bus card cannot "see"; unsure whether fabric only card will "see" data on the main bus - data can be transferred between main bus and fabric on sup720) and you're unable to use "compact mode" (reducing the main sups maximum forwarding performance by half or more).

If you mix classic bus and CEF256 cards in the same chassis, I recall there's an option to tell the CEF256 cards whether to place their data on the share bus or the fabric.  The former enhances data transfer between a classic bus card and a CEF256 card, the latter enhances data transfers between fabric cards.

Basically, you can mix and match many line cards in a 6500 chassis, but some line card mixes work better together.  Overall performance for "same" port speed, on different cards, can vary due to architectural differences.

Unless you have very busy line cards (or high aggregate across all the line cards), DFCs might be one of the last things you need to worry about.  I've seen Enterprise 6500s work fine loaded up with with gig and 10g ports, but all just running on the main sup, and I've seen Service Provider 7609s maxing out DFCs on 6704s.

On older line cards, e.g. again like your 6148, it's very common to see port drops when running its ports at gig.  This can be somewhat mitigated by how you distribute your hosts to port groups.

Hall of Fame Super Bronze

WS-X6724-SFP module

All that verbiage just to reiterate what I said?

Super Bronze

Re: WS-X6724-SFP module

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Edison Ortiz wrote:

All that verbiage just to reiterate what I said?

Laugh - yup.

It's, I think, just a little more than just a reiteration of what you said, hopefully it's an expanded clarification and I also think it adds some new information that might have relevance to the OP if they're concerned about performance.

Nothing you wrote was "incorrect" but my experience has been those less knowledgeable about 6500s might draw the wrong conclusions, such as perhaps if you have DFCs you're guaranteed to see a dramatic performance improvement or classic bus line cards will always directly exchange data with CEF720 cards across the classic bus (such, I don't believe you intended to imply).

I work in an enviroment where, for example, divison will upgrade one of their 6509s from a sup32 or sup2 to a sup720 and expect a dramatic performance improvement although all the line cards [classic bus] remain the same.  Or, they believe all gig ports on all line cards types will deliver the same performance - because they are gig ports. So forgive me for my verboseness, but this is a bit of a hot button for me. 

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