3750X or 4948 10G top of rack recommendation

[lee.a.connell]

I posted this once already and I don't see it in the forums, so I am posting again.

Is the low latency of the 4948 10G worth purchasing over the 3750X with stacking?

3750X with stackwise makes it easier to configure and gives a 64Gbps inter-connect, where as the 4948 in my situation would have a 10Gbps fiber inter-connect.

I plan on starting out with two switches for redundancy connected to vsphere hosts utilizing mpio.

Advice?

[Joseph W. Doherty]

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Posting

I believe you'll find that latency across a 4948-10G isn't that much better, if at all, than a 3750X as I don't recall the former offering cut-through switching.

Besides the major difference between the two, where the latter has stacking (BTW, the newer 3850 offers 480 Gbps interconnect - at about the same price), the 3750X doesn't have port buffers as generous as the 4948.  This often can be a problem if there's microbursting.  Choice might be best made depending on what you expect per port behavior will be.

[lee.a.connell]

Thanks for the response.  I'll give you a breakdown of how the network is going to be setup.

CORE: 2 x 3750X (Stacked)

ACCESS: 4 x 2960X (Stacked)

ToR: 2 x 3750X (Stacked)

ACCESS and ToR will have 10Gbps uplinks to the CORE.

The ToR switches are going to be used for multipathing and redundancy to 10Gbps iSCSI storage and 4Gbps (Cross-Stacked EtherChannel) vSphere hosts.

+++++++++++++++++

With that being said I have concern for port buffers as I have read people having issues with that on the 3750 vs the 4948. Should I be concerned?

Would I be better off with a 4506-E w/ Sup6-E as the CORE and the 4948 x2 for the ToR?

[Joseph W. Doherty]

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

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In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

iSCSI is exactly the kind of host that often causes issues for 3750s (as mentioned on these forums).  However, if the iSCSI is the only host with 10g, which will be on an uplink port, it might be okay.

The 4948 and 4500 with sup6 are both more "industrial strength" than the 3750X, although with 4506 you loose core sup redundancy.

PS:

If you do go with the 3750X, would it be possible to stack all four units?

Have you considered the 3850?

[lee.a.connell]

I did notice I lose redundancy on the 4506, I would need to go 4507. I could stack all 3750X's, that is not a problem. What does that do for me instead of making two stacks out of them? I was going to keep the server/storage traffic on the ToR switches by using inter-vlan routing there.

I just looked at the 3850, it doesn't say anything about port buffers, I do see the higher stack bandwidth and memory on them. Is there something specific about them that I should be looking at?

Thank you.

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

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In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Correct, the 4507 can provide sup redundancy, although there's quite a price jump with the second sup and the more expensive chassis.

Well, having just one stack of 3750s allows you to use the stack ring rather than uplink ports between the "core" and ToR switches.

The advantage of the 3850, besides the much increased ring bandwidth, they're newer, and at about the same price, wouldn't be surprised if Cisco declares the 3750X series EoL in the near future.  Don't know if they improved port buffering, though.

[Leo Laohoo]

wouldn't be surprised if Cisco declares the 3750X series EoL in the near future.

You're not "coughing" Joe? 

[Joseph W. Doherty]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

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In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

No, not coughing this time - feel better. 

PS:

BTW, hmm, 3750-X is no longer listed, I believe, on overview switch product pages; you need to search "view all".

[Jon Marshall]

Joseph

I always end up usinfg the "view all" as i can never find the switch i want. I just can't keep up with Cisco adding new switches

I tend to stay out of these threads as they can be a bit of a minefield. I have read about the buffer issue with 3750s on these forums but i was wondering if you have any experience with the shared memory pool used by the 4500 series for port buffers. For some reason i find this a bit worrying although i have never used a 4500 as an aggregation switch with high bandwidth servers so i have never hit this issue before.

Ironically the 4900s would make a really nice small distro/core switch for this type of thing if only they were either stackable or suppoted VSS.

Jon

[Joseph W. Doherty]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

I always end up usinfg the "view all" as i can never find the switch i want. I just can't keep up with Cisco adding new switches 

Laugh, me too!  Although that listing contains so many devices I sometimes find it difficult to find what I'm looking for.

I tend to stay out of these threads as they can be a bit of a minefield. I have read about the buffer issue with 3750s on these forums but i was wondering if you have any experience with the shared memory pool used by the 4500 series for port buffers. For some reason i find this a bit worrying although i have never used a 4500 as an aggregation switch with high bandwidth servers so i have never hit this issue before. 
Ironically the 4900s would make a really nice small distro/core switch for this type of thing if only they were either stackable or suppoted VSS.

BTW, I think the latest 4948E supports VSS.

Regarding using shared memory pools, the 3750X without QoS enabled, or with QoS enabled but with non-default buffer settings, can operate with a shared (i.e. "common" in 3750 speak) pool.  The problem doesn't seem to be with sharing, just that 2 MB for 24 gig ports, often just isn't enough.

Also BTW, I believe the earlier 35xx series didn't have as many port drops issues as the 3750X series, and I also believe it uses a shared pool (8 MB?).

My present employer had used ToR 4948-10Gs in our data centers.  As far as I know (I don't support the data centers), they were happy with their performance but they've been upgrading to Nexus (extended fabrics for ToR).

[Jon Marshall]

BTW, I  think the latest 4948E supports VSS

If that is the case i would very tempted for a small core /distro to use a pair of these.

The other main reason i tend to stay out of these threads is, not having worked for a while, i have no idea of costings so it's very hard to recommend something when it could be completely out of the budget range.

Jon