Replacement of 3750E as a core switch

Unanswered Question
Apr 24th, 2008

Hi all,

I have sold one of my customers 5 numbers of 3560 switches for his five locations in same premises and he has gone for 3750E switch as a core switch but now he wants to use optical fiber uplink ports of 3560 switch to connect them to core switch.

As 3750E don't have more than 2 optical fiber ports he wants to rplace it with the core switch which should have all 3750E facilities with at least 8 fiber optic ports so that he can terminate fiber optic cable directly on core switch from uplink ports of 3560 switches.

I think he will have to connect all 3560 switches seperatly to core switch for that he will need at least 5 fiber optic ports on core switch.

Please suggest me a good economical core switch where he can terminate 3560 switches derectly using fiber optic cable and suggest me SFP module he will need and number of SFP modules or will he need any other fiber optic cable as he wants to connect all 5 numbers of 3560 fiber uplink ports to core switch normal fiber ports.

One guy suggested the following solution...

Assuming L3 is needed on the core switch you can pick from below

1) ME4924-10G (28 SFP ports)

2) 4900M with 8p10G card and twingig (makes it 16p SFP)

3) 4503 chassis with 2 6p GBIC (or SFP) cards and Sup

4) ME6524

Optics .. for each link you need one cable and 2 SFPs.

SX SFP is good if you have multimode fiber and less than 500m

LX SFP is good if you have singlemode fiber and less than 10km

but the customer need cost effective solution. So please help me in providing a solution for his requirement.

Thanks in advance..

I have this problem too.
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Sushil Kumar Katre Thu, 04/24/2008 - 23:27


To start with, 3750-E comes with 2 10 GE uplink interfaces. You can use the TwinGig convertr and have 4 1GE SFP instead of 10GE interfaces.

3750E switch uses StackWise Plus mode providing 64 Gbps stack connectivity while 3750 uses StackWise mode providing 32 Gbps stack connetivity.

My suggestion would be to add Cisco Catalyst 3750G-12S-12 [Gigabit Ethernet SFP ports] switch on the 3750E stack [you can have a combination of 3750 adn 3750E switch in the same stack]. The new switch will provide 12 SFP interface to connect 3560 switches.

Once you have both these switches in the stack, 3750-E detects a non-E-Series 3750 switch and will negotiate down from StackWise Plus mode to StackWise mode. Thus, the entire stack will now run in the original StackWise mode 32Gbps stack connection. This is the only drawback.

Use 1000 base-SX Multimode Fiber for connectivity upto 550 mts.

1000Base-LX/LH Single Mode fiber for higher range.

-> Sushil

Sushil Kumar Katre Fri, 04/25/2008 - 04:24

I missed out these switches. You can definitely go for 3750E switches suggested by Joseph. 64gbps Stak bandwidth.

-> Sushil

Paolo Bevilacqua Fri, 04/25/2008 - 04:59

There are also L2 switches with all SFP, the new 2960s. If you can do L3 elsewhere, it should not matter to you. I call this class of switches fiberhubs :)

Sushil Kumar Katre Fri, 04/25/2008 - 05:55

Hi Paolo,

I was not able to locate any 2960 switch with all SFP ports.

Can you let me know the model number you are referring to. That would be a sweet little switch.

-> Sushil

Paolo Bevilacqua Fri, 04/25/2008 - 07:50

You are right, I was confused when said that :)

Anyway, one could also consider to eliminate the core switch altogether and just connect directly the switches uplinks temselves in any reasonable topology.


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