Stacking / LAG Bandwidth question.

[pierschandler]

Hi,

I wish to stack / link a SG500-52P and a SG500-28 over up to 4 available MM 50 /125 fibre.

Basically the patch panels to all the desktops is in the basement where there SG500-52P is, and the server are on the floor above where the SG500-28 there is a Fibre Patch panel between the 2 with 4 available fibre’s.

Obviously the majority of communication will be between the desktops and the servers so redundancy on the link and maximum bandwidth are the most important.

A stack gives me IP and easy management but does it give me maximum bandwidth?

I set it up using 2 X 1G native stack in S3 & S4 the other day but one of the fibre's kept disabling itself I put it down to a problem patch lead and left only one 1G fibre link in place and intend to return with a new lead this week. However it occurred to me after, was it STP disable the link or the presumed faulty cable?

So what is the best way to link these 2 switch for maximum bandwidth (BTW they are more then 10 Meters apart so the 5G is out)? 

Thanks in advance fro any replies.

Piers

[Tom Watts]

Hi Piere, the speed between is full duplex so if you lag 4 gig ports together it is 8 gbps (4 each way) throughput.

If you're using 5 gig or 10 gig ports you can figure this out

I do believe there is a SFP-H10GB-CU10M that will work as well but I can't confirm this.

But fyi, if you do plan to LAG 5 or 10 gig ports, I don't think you'll ever reach that speed. Even most ISP use 10 gig links and they aren't nearly peak utilized (most of the time)

-Tom
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[pierschandler]

Hi Tom,

Thanks for the reply, unfortunately not that useful, as stated above the switches are not the 10G models and there is more than 10 meters distance between them so no option to use the 5G stack cable in out.

So I have 4 X 1G fibres available what is the best way to link the switches?

and to answer that that involves 3 sub questions:

Using the native Stack Mode across 2 X Fibres does this provide a 2G link (Full Duplex) or a fail over 1G link (Full Duplex)?

Can you combine 2 X 2G Stack Links to give you 4G (assuming 2G is the answer to the above)?

Does a 4G LAG link offer any advantages? 

Piers

[Dan Miley]

The benefit of a lag, is that the load is shared across the links, assuming you have more than one connection.

so lag of 4 gig ports gives (somewhat less than) 4g throughput.

Stack mode gives the advantage of treating all the switches as one administrative device. 

The link is basically one Gig through put with failover.

You don't mention what type of applications are being used, server speeds, etc.

is it file sharing, browsing and email, (low end)

or video development and large database (at the other end)

but functionality wise, if it was my network I'd go with a 2 port lag, monitor the performance of the lag with SNMP (PRTG, Nagios, MRTG, Solarwinds, etc) and have 2 pairs of fiber for expansion if needed.

If you are fully utilizing 2gb with multiple servers/hi use/high bandwith apps, I'd think about the X models that do 10G fiber. (stack or uplink)

Dan

[Tom Watts]

Hi Pier, I would stand by my original post. The reason being you may  use the 5 gig link stack ports and use a ring topology which would be  the correct solution to get maximum throughput, easiest management and  least amount of physical connections.

Right now I have 2 SF500-28p stacked using a  SFP-H10G-CU3M wire and the stack negotiates at 5 gig since the s3/s4  supports 5 gig fiber.

So if you want redundancy,  maximum throughput, I'd recommend to to use the Cisco SFP-H10GB-CU10M  copper cable. This will negotiate your 5 gig links, give you the 30 feet  (10 meter) and 5 gig links on a single media.

Topology is Chain

Stack image auto synchronization is enabled

Unit         Stack Port #1                 Stack Port #2         After Reboot

---- ----------------------------- ----------------------------- ------------

No.  Port  Connected  Operational  Port  Connected  Operational  Stack  Speed

           Unit       Speed              Unit       Speed        Ports

---- ----- ---------- ------------ ----- ---------- ------------ ------ -----

1    S3       2           5G       S4   link down      Down     S3-S4  auto

2    S3       1           5G       S4   link down      Down     S3-S4  auto

-Tom
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[pierschandler]

Hi Tom,

I agree, but as mentioned they are 60 feet apart so not an option, so unless I missed something the 5G option is only available using a specific Cisco 5G Stack Cable with built in sfp at each end available in 1M, 3M, 5M and 10M. as the Longest 10M and I need 20M.

Piers

[pierschandler]

Hi Dan,

Thanks, OK i will go with LAG then.

As for the Bandwidth requirement I would say it is medium, there is 5 Server (DC, Exchange, Apps, SQL, File & Print) but only about 15 users. The heavy bandwidth usage comes from file synchronising with their laptops (4 - 5 GB). It is the file syncing that is the problem when 2-3 users do it at the same time (beginning and end of day typically). Up until last week the desktops were on 100Mb and the servers multiple Gig links and a 2G LAG Link to the desktop switch. So the bottleneck was the 100Mb desktop link. I thought the 10G was a bit overkill and the 4x1G should cope / be a good improvement. My question was to find out how to best utilise the 4G link which seem LAG is the way to go.

Do I need to check / confirm the actual bandwidth requirement or as the 4 Fibres are in place and connected, I assume I may as well use them even if that bandwidth is not required it won't do any harm?

Regards

Piers