DC Extension using CWDM Chassis

Answered Question
Mar 2nd, 2010

Hello all,

I have a project to interconnect 2 DC's using one existing fibre (Pair actually).

The 2 DCs are less than 50 km away

We would like to have dual 4Gbps Fibre Channel for our SAN and dual 1Gbps Ethernet

I was thinking in the below kit to achieve this:

CWDM-CHASSIS x2

CWDM-MUX8A x4

CWDM-1530 x4

CWDM-1510 x4

CWDM-1490 x4

The kit above is going to interconnect the SAN (Fiber Channel side is 4x MDS 9124 switches) and the LAN (the Data side will be 4x Catalyst 3750G switches).

I am struggling with 2 things here:

1 - The correct SFP's on the switches (both FC and LAN) to achieve the requirements

2 - If the equipment will achieve the required bandwidth for the given distance ...

Can anyone point me out in the right direction here ? (or any documentation about it ...)

Thanks

Nuno Ferreira

I have this problem too.
0 votes
Correct Answer by viyuan700 about 6 years 9 months ago

When it says 1 wavelength ptp does it means that the fibre is entirely used for that link ? If this is the case then I will not be able to do the 4G FC

"1 wavelength ptp does it means that the fibre is entirely used for that link" i think you are trying to say that connecting SFP directly (As it doesnot make sense to have CWDM/DWDM for 1 wavelngth) over the pair of fiber. Yes then you cannot multiplex anything else.

So if I go for 2G FC I can have 8 wavelengths on the same fibre - So I will be able to have 2 links of 2G FC and 1 link of GE ... right ?

DS-CWDM-1470=(For Fiber Channel)

CWDM-SFP-1470 (For Ethernet)


Above SFP have link budget of apprx 30dBm so can go 50Km. If these 2 SFP doesnot solve ur problem then you have to go with DWDM solution/other vendor who can provide you 50Km.

Now to complicate even more I know that the CWDM can now be amplified. Can I use some kind of SFP that by amplifying can actually increase the distance ?

Cisco CWDM dont amplify it is passive system as mentioned in Tom post u can see the system from MRV or any other vendor who has. There were  some SOA amplifier which were in news for CWDM but i dont know whether they are commercially available.

Correct Answer by Tom Randstrom about 6 years 9 months ago

/* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

I will give this a try, inline below……

From what I know of my studying days I remeber that the standard used for CWDM (When it couldn't be amplified) was:

*** This is correct.  There still is not a commercially available amplifier that covers all the CWDM channels.

120 km for Gigabit Ethernet and 100 km for 2G FC - this is obviously in Point to Point topologies - which is my case.

The above sorts the problem of the Gig links out.

Then from my Storage books (Yes I had to go to the atic to look for them) I have that CWDM can do for 4G FC the following:

- 8 multiplexed wavelengths at up to 30 km (What I wanted to know is what are the SFPs used in this case)

*** The 4G FC CWDM SFP model number is “DS-CWDMG-xxxx” (xxxx = wavelength that matches wavelength on mux)” that can be used with the CWDM-MUX8 to reach 30km. Use the “DS-CWDM-xxxx” for the GE connections. Being run over the MUX.

- 1 Wavelenght point-to-point at up to 40 km (Again what are the SFPs used here ?)

*** The 1/2G FC SFP model number is “DS-CWDM-xxxx” can be used as a single wavelength per fiber solution for up to a 60km link.

Now my question is if the DCs are 40kms away form each other and I choose to use the last option - 1 wavelength ptp Will I loose the ability to have the fibre multiplexed to the other circuits I need ? (At least my Gigabit Ethernet) ?

*** The MUX8 is the device that provides access to the fiber for more than one FC or GE channel.  When you add the MUX, it adds additional loss of light (attenuation) to the link. 

If i decide to go to 2G FC then I have:

- 8 Multiplexed wavelengths at up to 50 km

- 1 Wavelenght ptp at up to 80 km

So if I go for 2G FC I can have 8 wavelengths on the same fibre - So I will be able to have 2 links of 2G FC and 1 link of GE ... right ?

*** You could mux any combination of up to 8 channels;  GE or 1/2G FC.  The MUX8 puts 8 channels on each fiber; transmit on one fiber, receive on the 2nd fiber. 

When it says 1 wavelength ptp does it means that the fibre is entirely used for that link ? If this is the case then I will not be able to do the 4G FC ...

*** If you want to do 4G FC above 30km, you will be limited to one channel per fiber (no additional signals on the fiber).   

Now to complicate even more I know that the CWDM can now be amplified. Can I use some kind of SFP that by amplifying can actually increase the distance ?

*** I am unaware of an amplifier for CWDM band.   

Thanks again and sorry to not have been more specific like this on the first post ...

***You should send a message to MRV Communications and clarify whether they can actually reach 50km with their 4G FC CWDM and 8 Channel MUX.

Nuno Ferreira

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (2 ratings)
Loading.
Nuno Filipe Alv... Wed, 03/03/2010 - 03:40

Hi Jerry,

Thanks for the reply. And what would be the waveleght to use form the above ones for this specific link ? Any ?

The sfps available for the Storage Switches are pretty much the same as for Data ones but I still don't know which ones to use to achieve what I need ...

Thats the main question ...

Thanks

Nuno Ferreira

Marvin Rhoads Wed, 03/03/2010 - 06:18

Which particular wavelength (color) you chooose isn't important so much as it is to make sure you match them across a given transmission span. Match your colors and do the link loss power calculations (transmit power + link loss budget = net within receiver's sensistivity range) and you should be fine.

The green, blue, and viloet SFPs you mentioned in your original post would be OK. All other things being equal, some designers go with non-adjacent wavelengths (such as offered in the 4 color kits) just to build in some additional tolerance betweeen the transmission bands. Not strictly necessary but a common practice.

Jerry Ye Wed, 03/03/2010 - 06:42

Agree with MKlemovitch,

You just have to match the color on both end, and make sure your power is within budget.

Need to correct some info on my previous post. Found a page for the CWDM SFP spec's. Here you go

http://www.cisco.com/en/US/prod/collateral/ps4159/ps6409/ps4358/product_data_sheet09186a00801bc698.html

In the 2nd half of Table 1, you will find DS-C9124-K9 and the supported SFP's.

HTH,

jerry

Tom Randstrom Wed, 03/03/2010 - 08:25

/* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

The 4G FC CWDM SFPs for MDS 1524 are DS-CWDMG-xxxx, based on the SFP compatibility link provided by an earlier response.  These CWDM SFPs, per the data sheet, have the following specs:

1.0dB = Tx max

-15.7dB = Rx min

16.7dB = Link budget

4.4dB = CWDM MUX-8 Insertion Loss (includes both sides)

3db = Typical system margin to provide for degredation

.25 = Fiber loss @ 1550nm, typical (assumed this includes fusion splices in fiber link)

Calculating the “link length”,

16.7dB link budget

- 4.4dB Mux/Demux insertion loss

======

12.3dB fiber link

- 3dB Aging margin

======

9.3dB fiber link including margin

÷.25dB fiber loss/km @1550nm

======

37 km reach

If you are trying to reach 50km, then this solution will not be sufficient for the application.  Additionally, these “back of napkin” calculations do not include losses for any optical connectors that may be in the path.  It is best to have the fiber link tested for actual loss to determine an accurate starting point.

There are other potential options.  MRV sells a Fiber Driver FC Repeater, which has a 4G FC extended reach DWDM SFP.  This would provide ~16.6dB/66km reach (same assumptions as above); and could feed the CWDM Muxes you indicated using in your post. 

http://www.mrv.com/product/MRV-FD-FC400B

http://www.mrv.com/datasheets/OP/PDF300/MRV-OP-SFPFC4CW_HI.pdf

There are also many other CWDM/DWDM transport systems that would also work for your application (IE Cisco ONS 15454 MSTP). These tend to be more complex, but offer additional carrier class features.

I hope this helps…..

Nuno Filipe Alv... Wed, 03/03/2010 - 09:23

Thanks for all the answer ..

So basically the problem here is to do the 4G FC link right ? Because of the distance.

Is it possible to do 2x 2G ? Where Can I access a calculator or a table showing the distances for each technology / equipment ?

I believe that for DWDM cisco uses the ONS platform right ?

What is the combination of equipment for the CWDM Chassis that can cover more distance ?

Thanks

Nuno Ferreira

viyuan700 Wed, 03/03/2010 - 10:50

Hi,

Yes 4Gb has link budget of 17.8dBm and as per that u can go around 40Km.

1/2Gb is giving you more link budget approx Approx 30dBm. So you will get 50Km without problem with extra 10-12dBm of power.

CWDM are passive device and u cannot extend further in cisco  but you can see other vendors if they have optical amplifier for CWDM system.

Few things you can consider like your future growth as CWDM are for 8 Wavelength, will that be enough for sometime.

These will be point to point link do you need ring kind of redundancy for your DC.

ONS platform are scalable  (in number of wavelength and in speed if want to go for 10G ethernet etc) and can provide redundancy but do you have budget and more than budget do you need those extra features.

Nuno Filipe Alv... Wed, 03/03/2010 - 12:44

Gents, again thanks for the help ...

From what I know of my studying days I remeber that the standard used for CWDM (When it couldn't be amplified) was:

120 km for Gigabit Ethernet and 100 km for 2G FC - this is obviously in Point to Point topologies - which is my case.

The above sorts the problem of the Gig links out.

Then from my Storage books (Yes I had to go to the atic to look for them) I have that CWDM can do for 4G FC the following:

- 8 multiplexed wavelengths at up to 30 km (What I wanted to know is what are the SFPs used in this case)

- 1 Wavelenght point-to-point at up to 40 km (Again what are the SFPs used here ?)

Now my question is if the DCs are 40kms away form each other and I choose to use the last option - 1 wavelength ptp Will I loose the ability to have the fibre multiplexed to the other circuits I need ? (At least my Gigabit Ethernet) ?

If i decide to go to 2G FC then I have:

- 8 Multiplexed wavelengths at up to 50 km

- 1 Wavelenght ptp at up to 80 km

So if I go for 2G FC I can have 8 wavelengths on the same fibre - So I will be able to have 2 links of 2G FC and 1 link of GE ... right ?

When it says 1 wavelength ptp does it means that the fibre is entirely used for that link ? If this is the case then I will not be able to do the 4G FC ...

Now to complicate even more I know that the CWDM can now be amplified. Can I use some kind of SFP that by amplifying can actually increase the distance ?

Thanks again and sorry to not have been more specific like this on the first post ...

Nuno Ferreira

Correct Answer
Tom Randstrom Wed, 03/03/2010 - 14:09

/* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

I will give this a try, inline below……

From what I know of my studying days I remeber that the standard used for CWDM (When it couldn't be amplified) was:

*** This is correct.  There still is not a commercially available amplifier that covers all the CWDM channels.

120 km for Gigabit Ethernet and 100 km for 2G FC - this is obviously in Point to Point topologies - which is my case.

The above sorts the problem of the Gig links out.

Then from my Storage books (Yes I had to go to the atic to look for them) I have that CWDM can do for 4G FC the following:

- 8 multiplexed wavelengths at up to 30 km (What I wanted to know is what are the SFPs used in this case)

*** The 4G FC CWDM SFP model number is “DS-CWDMG-xxxx” (xxxx = wavelength that matches wavelength on mux)” that can be used with the CWDM-MUX8 to reach 30km. Use the “DS-CWDM-xxxx” for the GE connections. Being run over the MUX.

- 1 Wavelenght point-to-point at up to 40 km (Again what are the SFPs used here ?)

*** The 1/2G FC SFP model number is “DS-CWDM-xxxx” can be used as a single wavelength per fiber solution for up to a 60km link.

Now my question is if the DCs are 40kms away form each other and I choose to use the last option - 1 wavelength ptp Will I loose the ability to have the fibre multiplexed to the other circuits I need ? (At least my Gigabit Ethernet) ?

*** The MUX8 is the device that provides access to the fiber for more than one FC or GE channel.  When you add the MUX, it adds additional loss of light (attenuation) to the link. 

If i decide to go to 2G FC then I have:

- 8 Multiplexed wavelengths at up to 50 km

- 1 Wavelenght ptp at up to 80 km

So if I go for 2G FC I can have 8 wavelengths on the same fibre - So I will be able to have 2 links of 2G FC and 1 link of GE ... right ?

*** You could mux any combination of up to 8 channels;  GE or 1/2G FC.  The MUX8 puts 8 channels on each fiber; transmit on one fiber, receive on the 2nd fiber. 

When it says 1 wavelength ptp does it means that the fibre is entirely used for that link ? If this is the case then I will not be able to do the 4G FC ...

*** If you want to do 4G FC above 30km, you will be limited to one channel per fiber (no additional signals on the fiber).   

Now to complicate even more I know that the CWDM can now be amplified. Can I use some kind of SFP that by amplifying can actually increase the distance ?

*** I am unaware of an amplifier for CWDM band.   

Thanks again and sorry to not have been more specific like this on the first post ...

***You should send a message to MRV Communications and clarify whether they can actually reach 50km with their 4G FC CWDM and 8 Channel MUX.

Nuno Ferreira

Correct Answer
viyuan700 Wed, 03/03/2010 - 14:51

When it says 1 wavelength ptp does it means that the fibre is entirely used for that link ? If this is the case then I will not be able to do the 4G FC

"1 wavelength ptp does it means that the fibre is entirely used for that link" i think you are trying to say that connecting SFP directly (As it doesnot make sense to have CWDM/DWDM for 1 wavelngth) over the pair of fiber. Yes then you cannot multiplex anything else.

So if I go for 2G FC I can have 8 wavelengths on the same fibre - So I will be able to have 2 links of 2G FC and 1 link of GE ... right ?

DS-CWDM-1470=(For Fiber Channel)

CWDM-SFP-1470 (For Ethernet)


Above SFP have link budget of apprx 30dBm so can go 50Km. If these 2 SFP doesnot solve ur problem then you have to go with DWDM solution/other vendor who can provide you 50Km.

Now to complicate even more I know that the CWDM can now be amplified. Can I use some kind of SFP that by amplifying can actually increase the distance ?

Cisco CWDM dont amplify it is passive system as mentioned in Tom post u can see the system from MRV or any other vendor who has. There were  some SOA amplifier which were in news for CWDM but i dont know whether they are commercially available.

Nuno Filipe Alv... Wed, 03/03/2010 - 16:18

Guys thank you very much .. I think I got everything I need

It makes sense now ... and I think I should definitely go back to query the true distance that the fibre is running for and then go back to MRV to querie if for that lenght of fibre I will be able to use the 4GFC (not as a ptp but as a 8 wavelengths multiplexed)

Thanks again gents

Nuno Ferreira

Actions

This Discussion