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Cisco 3750 - Fiber Connectivity

Posted on 2013-06-18
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Last Modified: 2013-09-16
Hi,
I am going to connect 6 switches on fiber for my 4 floor building,

I am attaching the low level network diagram for clear understanding here with,
below is my requirements:

All switches should get connected each other with redundant link (if one fiber cable is damaged second one should be available as a backup, so we will have the redundant link with each floors (not the redundant switch on each floor)

Kindly clarify my some queries as below:

1. My cable vendor shipped me single mode fiber cable for interconnecting the switches, so is this cable fine or do I have to go for mulimode fiber cable?
2. My cable vendor says ... you have to use SC-LC single mode Duplex adapter=is it correct? as cisco 3750X / 2960S SFP module will be compatible with LC connectors=True?
3. What SFP module I have to order if I have to go for 1G or 4G fiber = SC or LC? confused?
4. My cable vendor says ...you have to use SC/PC Pigtail OS2 PVC 1.5 m  + SC to LC fiber connector...so what does he exactly mean by this?,,, &.. what I understood is...my 2960S switch connect as below:
Cisco2960--->SFP--->---LC connector--->----fiber---------> SC/PC Pigtail <----------fiber------------ LC connector---< ----Cisco3750X   ( pls correct if I am wrong anywhere)
5. As 3750X comes with 12 fiber ports + 4 extra modules ports so all my 6 switches(6X2=12ports = pls refer to the attached net-diagram) will get connected with each switch with redundant link but can i use 4 extra ports to connect my 2 physical server with this switch = if yes...what I have to use to get it connected?

I am really sorry for long story....

Can anyone pls help me to understand the connectivity will be done in cisco with fiber...

many thanks in advance...
Cisco-Fiber.jpg
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Question by:dxbdxb2009
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by:rauenpc
ID: 39257173
1. Single mode is fine as long as your transceivers (SFP's) are single mode. You just need to match things up
2. As far as the connector goes, I don't think you have a choice - it's LC. You'll just need to make sure to get a single-mode transceiver.
3. As with number 2, you don't have a choice in connector. You do have a choice in the type of SFP - SX (short distance) LH/LR/LX (long distance, usually single mode). 1G versus 4G... are we talking ethernet or fiber-channel here?
4. Um... the connectors just need to match up. As far as I'm aware both the 3750X and 2960S both use LC so to connect the two together you need an LC-LC fiber cable. However, if there is a patch panel between the two and the patch panel is SC, then you will need an SC-LC fiber patch cable to connect each switch to the fiber patch panel.
5. Yes. As with the other answers, the transceivers just need to match up. Not so much the connector as a fiber patch panel can have different connectors on each end, but the type is important - single mode doesn't work with multi mode. Most server vendors list which switch transceivers are compatible with their fiber cards. Or you can get a GLC-T which is a 1G copper RJ45 SFP. Then you won't need to worry about fiber to a server.
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by:dxbdxb2009
ID: 39258544
Thanks  rauenpc for your valuable reply,

1.  I will go for Single mode fiber cable,
2. Okay..so for switch's end I will go for LC connectors, SFP will be single mode=correct?
3. Connector will be LC; but SFP=? like in single mode will I go for SX or  LH/LR/LX (distance of each switch from core switch will not be more then 35 mts) connecting switches together would be on fiber only
4. so connecting back to back  3750X and 2960S directly can be done using single mode LC to LC cable (is there any need to put the fiber patch panel between 3750X & 2960S) as like we do with normal CAT6/copper cable  
so I can connect both 3750X & 2960S as below:
Cisco2960--->SFP--->---LC connector))))--->-------------fiber cable--------- (( LC connector---< ----Cisco3750X   ( pls correct if I am wrong anywhere)
5. I assume HP/IBM has the SFP which support LC connectors...if so...again can i diretly connect HP/IBM server Fiber card terminating to 3750X's SFP modules?

Much appropriate for your prompt advice/suggestions,,,

Thanks in advance...
Kindly advice ....
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by:dxbdxb2009
ID: 39260230
@ rauenpc  : pls advice/comments on my query...

thanks once again in advance..
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rauenpc earned 250 total points
ID: 39260532
2. Correct.
3. For 1G, 1000BASE-LX/LH (GLC-LH-SM). 10G would be SFP-10G-LR
4. if you are connecting back to back and this is within the same room I would say save some money and go with a long patch cable to connect the two directly. If there is a room or a floor between the two devices I would recommend a patch panel so that you can make changes in the future. This will accommodate hardware changes and moves.
5. Yes, you should be able to, but you still need to match the SFP type, or more specifically the frequency.

The above would be straight answers without throwing you any curves. But here's a slight curve. If none of the closets are further apart than 300M, you may be better off going with 50um MM fiber (OM3 or OM4). It's not so much that the fiber will save you money, but the price difference in SFP's is huge when it comes to 10G
As of today, list price is:
SFP-10G-LR=  3,995.00 (Single Mode)
SFP-10G-SR= 1,495.00 (Multi Mode)

When you multiply that out by the minimum 12 SFP's (just to get to your switches) that's a big difference - 47,940.00 for SM versus 17,940 for MM.

Use the links below to see the specs for different types of Cisco optics. When I say that you need to match the "type", I really mean the frequency. Frequency usually equates to a "type" like LR, SR, LX, LH, etc. Please excuse my use of the word type when referring to SFP's as it can be misleading.

For example, Cisco SFP-10G-SR has a frequency of 850nm, and Cisco FET-10G also has a frequency of 850nm. They do not have the same name, and do not serve the exact same purpose (the purposes are for a completely different topic), but they are compatible to communicate with each other directly because the frequency matches. This is a common pairing when using Nexus switches.
I would be willing to bet that the server fiber cards run at 850nm which means the SFP-10G-SR would be compatible and can use any of the listed fiber types within the distance limitations.

http://www.cisco.com/en/US/prod/collateral/modules/ps5455/data_sheet_c78-455693.html
http://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6577/product_data_sheet0900aecd8033f885.html
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Expert Comment

by:bfason
ID: 39261050
Just for clarification on the above. The WS-C3750X-12S-S only has 1G ports. The 4 port module is only available in 1G ports. So based on this you will not be able to use the SFP+ for 10Gb connectivity.

With that being said there is still a large price difference between "cisco branded" MM sfp's and SM sfp's.

There are several mfg that make sfp's that will work in cisco products and interestingling enough there's not much price difference between MM and SM. I've used Fluxlight will great success and saved quite a bit by doing so.

http://www.fluxlight.com/cisco-sfp-modules/?sort=bestselling

Hope this helps
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by:rauenpc
ID: 39261142
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by:rauenpc
ID: 39261146
The 3750x 12 does appear support 10g transcievers so I assumed it could support 10g. If that's not the case, it would be good to know before I suggest a solution to a customer that won't work. I'll do more research to find out.
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by:bfason
bfason earned 250 total points
ID: 39261170
Yes it can support 10Gb SFP+ transceivers on the 2-port network module addon card. The 4 port network module supports 1Gb modules. The 12 ports on the 3750X are 1Gb.

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps6406/data_sheet_c78-584733.html
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by:dxbdxb2009
ID: 39267609
@ rauenpc : thanks for your valuable comments,
Small changes here…
1.      I will go for multi-mode 4 or 6 core (OM3) not the Single mode fiber cable ( as advised transvers would be bit costly for SM)
2.      SFP transvers would be MM for fiber
3.      Thanks ..will go for 1G LX/LH
4.      As advised …. Will keep one fiber patch panel in MDF (Second floor) & will connect/terminat all switch in it & then will let it connect to Core switch……I am correct? If yes kindly advice any good brand/company of fiber patch panel with link? & if I am not wrong I will have to use the same MultiMode LC connector in this fiber patch panel or MultiMode  SC?
5.      SFP for servers….already ask the vendor…waiting for his reply
For Multimode fiber solution for interconnecting switches = totally agreed
& thanks for explain LR, SR, LX, LH, etc…
Will keep you posted asa I hear from my server vendor..
-------------------------------------------------------------------------------------------------------------
@ bfason : we are looking for 1G connectivity, but can you advice any cisco switch which can support 10G as well but prices should be bit competitive with 3750X..thanks
Pls note I need all ports 10G not only the 2/4 uplinks only. (if we go for 10G solution)
“several mfg that make sfp's……” kindly name 2-3 as I can not find any good one in UAE..
Thanks once again for your help…
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by:dxbdxb2009
ID: 39269149
any comments plssss
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by:bfason
ID: 39274995
Sorry I've been out of town and not checking in regularly.

You are not going to find a Cisco "core" switch for the same price as a distribution switch. You may find some other vendors switches that will come close. The next closest cisco switch would be the 4928 which would be twice the ports and 10x the speed for about 4x the price of the 3750.

As for SFP just google the part number. Every mfg I've seen uses the same part number as cisco to easily identify them. They will be pretty easy to spot as they will be listed as "Cisco Compatible" and be much cheaper than the cisco branded models.

Hope this helps
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by:dxbdxb2009
ID: 39311827
Thanks bfason for ur valuable information comments... I am out of town for 10 more days... Would really appreciate if u can bear me till the time I resume....
Thanks for ur understanding....
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by:bfason
ID: 39312786
Actually there is another alternative for your switch. I completely forgot about the 4500x fixed port switch. It would be a bit more than the 3750x but not nearly as much as the 4928 and still accomplish what you want.

Part#WS-C4500X-16SFP+ and you will have to add power supply depending on airflow config.

Hope this helps
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Author Comment

by:dxbdxb2009
ID: 39352793
thanks for your reply,

my mgmt is more interested into 3750x (edge) & 2960 (core) switches .... with 1Gigs fiber uplink ports

kindly advice the cisco & other cost effective sfp transceiver which can solve my propose,

thanks in advance..
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