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New Contributor
Posts: 4
Registered: ‎02-17-2009

Virtual Fabrics, logical switches, and the long distance fabric option

I am looking to deploy virtual fabrics into my existing environment.  My existing

environment is made up of 4900s, running 6.2.0g.  I am adding/merging DCXs and

DCX-4Ss running 6.2.1b and logical switches into the existing fabrics.

In today's environment there is extended distance in use on some of the 4900s.

NONE of the 4900s have the "long distance fabric" option set.  I am planning on

using extended distance on some of the logical switches being merged in, but I

wouldn't expect that the DCXs or DCX-4Ss would need the option either.  I say this

because of the 6.2 Troubleshooting Guide, which states that the long distance

fabric option is "not necessary on Bloom-based, Condor, GoldenEye, Condor2, or

GoldenEye2 fabrics." 

However, looking at the DCFM 10.1.4 User Guide, in the Virtual Fabric section,

it states that you should "select the Long Distance Fabric check box to enable

ISLs in a fabric to be up to 100 km long." 

I should state that there is nothing in the 6.2 Administrator's Guide about having

to set the "long distance fabric" option.

So, do I really need this option or not?  The Troubleshooting Guide makes it

sound like I don't need it.  The Administrator's Guide is quiet on it.  The DCFM

Guide is the one making the statement. 

If I do need this option on the logical switches it is going to cause a lot of

pain since you can't ISL between switches that do and don't have the option.

Thanks in advance for any help.

Will

External Moderator
Posts: 5,029
Registered: ‎02-23-2004

Re: Virtual Fabrics, logical switches, and the long distance fabric option

--->>>....there is extended distance in use ....

--->>>So, do I really need this option or not?

how long ist the distance exactly ?

TechHelp24
New Contributor
Posts: 4
Registered: ‎02-17-2009

Re: Virtual Fabrics, logical switches, and the long distance fabric option

The distance is 17km.

External Moderator
Posts: 5,029
Registered: ‎02-23-2004

Re: Virtual Fabrics, logical switches, and the long distance fabric option

In order to use higher Port Speed, you need the Fabric license to set Higher value of Buffer Credit's, othewise the port work as L0 also Base, and you get a transfer rate of around 500KB, and I don't think make any sense to implement BIG's 8GB DCX's Director for 500KB transfer rate.

If you don't intended to use Extended fabric License in the DCX must use for this Port 4GB SFP and not 8 GB SFP, because the 8GB work only as 8,4,2 GBit/sec for FC Protocols, 4 GB SFP work as 4,2,1

TechHelp24
New Contributor
Posts: 4
Registered: ‎02-17-2009

Re: Virtual Fabrics, logical switches, and the long distance fabric option

First, thanks for the replies.  However, I think you are confused in regards to what I

am talking about.  I am not talking about the extended distance license, I have that.

What I am talking about is the "long distance fabric" attribute,

"fabric.ops.mode.longDistance".  You can have the license without having the

attribute.  You can also use LD, LS, etc without having the attribute set.  Also, as

I pointed out in my question, the current Troubleshooting Guide states that you

don't need the attribute, "long distance fabric" for Bloom, Condor, Condor2,

GoldenEye, or GoldenEye2 ASICs.  What is worrying me is that the DCFM Guide

appears to indicate that you need it for virtual fabrics.

External Moderator
Posts: 5,029
Registered: ‎02-23-2004

Re: Virtual Fabrics, logical switches, and the long distance fabric option

I'm sorry, but I do not understand your question.

the confusion is in the question.

TechHelp24

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