Hardware limitation with module 6148

Unanswered Question
Jun 13th, 2008

Has anyone experience or know of any limitations with the 6148 module ports? We are running some markets data applications and noticed drop packets on the transmit and slow performance. The module only supports 10/100.

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Overall Rating: 4.5 (2 ratings)
Jon Marshall Fri, 06/13/2008 - 05:19


What is the full part number for the module. The WS-X6148-GE-TX supports 10/100/1000.

Is there another module you were referring to ?


Tshi M Fri, 06/13/2008 - 05:25

My apologies...below is the full part number:


Jon Marshall Fri, 06/13/2008 - 05:35


No problem.

Firstly the WS-X6148-RJ45V is a classic module which means it can only use the shared 32Gbps bus. So a lot depends on how many other classic modules you have in the chassis and/or what supervisor you are running ie.

A Sup2 with no SFM (Switch Fabric Module) can only supply a 32Gbps to all modules in chassis regardless of whether they are fabric enabled or not.

A Sup32 is the same - as above and you cannot add an SFM.

A Sup2 with an SFM could provide fabric enabled cards with a connection to the crossbar switch fabric which would mean only the classic modules need access to the shared bus.

Finally a Sup720 can always provide a connection to the crossbar switch fabric.

So if all your modules were classic modules or you only had a Sup that supported classic modules then it could become a problem especially if some of your other classic modules support gigabit speeds.

In addition this module has a small buffer size per port in comparison to a lot of the more recent modules - 128Kb only, which again could be affecting performance.

This module is designed for the wiring closet so if you are using it for servers it may well become a bottleneck.

Edit - apologies Edison - went off on one of my explanations and i'm not the fastest typist :-)


Tshi M Fri, 06/13/2008 - 05:49

Hi Jon,

I have 3 other WS-X6148-RJ45V modules and running Sup32.

Jon Marshall Fri, 06/13/2008 - 05:51


Now i'm a bit confused :-).

If you have a sup32 how are you running a WS-X6748-GE-TX or are you referring to a different chassis ?


Tshi M Fri, 06/13/2008 - 11:08

No, the SUP32 goes with WS-6148-RJ45 but I also had two switches with SUP720 which have the WS-X6748-GE-TX.

Edison Ortiz Fri, 06/13/2008 - 05:28

Perhaps Etienne is referring to the WS-X6148A-RJ-45 module.

Etienne, this module is marketed for low bandwidth demanding devices (workstations & printers). This module is 1.2:1 oversubscribed and has very small port buffer which is shared among the 8 ports.

For market data traffic, I highly recommend DFC enabled modules such as 6748.




Tshi M Fri, 06/13/2008 - 05:35

Hi Edison,

I just moved the worstation to the mentioned hardware (WS-X6748-GE-TX). I will keep you posted.


Jon Marshall Fri, 06/13/2008 - 05:42

Hi Edison

Just a quick question.

How is this module 8:1 oversubscribed as it is only capable of 10/100 and not gigabit speeds ? And so 100 x 48 = 4.8Gbps and it has access to the 32Gbps shared bus ?


Edison Ortiz Fri, 06/13/2008 - 05:48

How is this module 8:1 oversubscribed

What are you talking about? ;)

I just edited my post

Tshi M Tue, 06/17/2008 - 06:37

Hi Edison,

If I were to use any other switch other than the 6500/7200 series, what switch would you recommend?

Edison Ortiz Tue, 06/17/2008 - 06:52

What are your requirements ?

If you want a server farm 10GE non-modular chassis model, the 4948-10GE is a very good switch.



Tshi M Tue, 06/17/2008 - 06:57

Thanks for the quick reply. No, it is not for a server farm but yes I was actually just going through the 4948 data sheet. I am looking at trading in the 6506-E with SUP32 for a better switch. So i am looking at the 4948...


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