Suggestions welcomed: Jumbo frames w/ 1gb connections

Posted on 2007-11-30
Last Modified: 2013-11-09
Hello All!

I'm aware that some here have already asked this question but I have a few more questions.

1. I have 100mb network backbone right now.  I'd like to speed that up.
2. What kind of hardware would be needed?  I was looking at an adapter that supports jumbos.  Which cards are best for this?
3. What kind of adapter do I need on the server to promote these speeds.  Some have said that pci slots are too slow.  So what do I need, PCI-e ?  
4. Also, there are devices on the network that not jumbo frame compatible.  So, I'd like to get a managed switch with VLAN support.  I could use this and separate jumbo and non jumbo devices.

Is this setup correct?  And if so what vendor do you suggest?

Thanks in advance.
Question by:rlocone
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Accepted Solution

SwassLikeMe earned 500 total points
ID: 20386968
There is no real point to using Jumbo frames on a 100mb network.  You'll want gigabit for this, and it should have specific purpose behind it.  For example, Oracle interconnect for the back end, where Oracle natively speaks with large packets that are normally broken up into smaller pieces with 1500 byte packets.  Jumbo frames would allow it to speak more efficiently.  iSCSI is another one that would benefit from this.

As you guessed, you can not have Jumbo frame and non-Jumbo frame exist on the same network and actually talk together.  The hardware, both network cards and routers/switches need to have sufficient frame buffer space to handle Jumbo frames.

Most newer server gigabit cards support Jumbo frames, should you choose to use it.  There is no requirement for PCI over PCI-e for Jumbo frames -- this is based more on the card you are putting in it.  A single gigabit connection can work fine in even a 32bit 33MHz PCI slot, since the bus is still faster than the card can transfer.

Yes, a switch that supports Jumbo frames can route between Jumbo and non-Jumbo, but it's inefficient.  The best purpose for Jumbo frames is exclusively on it's own network and not talking to anything else outside of it's network.

Author Comment

ID: 20386979
I just wanted to make my network go faster.  What I was going to do is split a switch up with VLAN and place non-jumbo devices on one side of the switch and jumbo enabled devices on the other.  The slower devices would go on the non-jumbo side.  I know that there is something called Q tagging.  So you don't have to worry about fragmentations.

Expert Comment

ID: 20386997
I understand.  I think my point was that you're not really going to benefit from this unless you have a very specific purpose in mind.  The purpose of the jumbo frames is really to eliminate fragmentation of data blocks, such as with iSCSI and Oracle backend communications.  Standard network traffic is not likely to see any real benefit from doing this. iSCSI is a very demanding protocol on the network, and between the target and the initiator, you will see fair performance improvements by turning this on.

Certainly the vLANs are a good idea for a network anyway, since you can segment areas of the network to eliminate things like broadcast traffic and the like.  It also can add a lot of security to your network.

All that said, if you're really wanting to do it, you'll be looking at more modern equipment and network cards, generally with gigabit interfaces and a large enough frame buffer to handle this.  The manufacture should be able to tell you if they support it on the equipment, even if they don't advertise it.

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Expert Comment

ID: 20387012
As an example, I use jumbo frames on broadcom and Intel based server cards with new 3750 Cisco switches.  Some of my older Cisco switches wouldn't work with it.  I have one 6509 that will, but that's a backbone switch and I didn't want to use it for this purpose.

I seem to think some switches may be all-or-nothing with regard to Jumbo packets on the switch, even when using vlans.

Author Comment

ID: 20387018
Ok.  so for what I want to use it for would be a waste of time and money.  What about just using gigabit speed alone?  With the jumbos that would have reduced cpu load.  But with a single server and 8 clients that shouldn't be no big deal.  I though maybe HD stream video would benefit from this.  I'd like to stream HD video stream to my workstations from the server.  

Expert Comment

ID: 20387081
Yeah, I just don't want to lead you down that path unless you said that you were connecting to a NetApp Filer storage array via iSCSI with TCP off-load cards.  Then I'd say you'd benefit from it for sure.  Or if you were using NFS to something like that, for example, and running databases off of it.

The CPU load differences would be pretty minimal in most cases, but if you're interested in reducing CPU load, look for server cards with tcp off-load engines.  That way the hardware can do the TCP checksums and leave the CPU out of the mix, allowing it to work more efficiently.  The only caveat to tcp off-load is when you use a network sniffer on the system using TCP off-load, you'll likely see tons of checksum errors that don't make sense, but can be ignored.  With these off-load engines, typically the OS has to support it.  If it is a Windows system, you'll probably be in luck, as with Linux, it's more of a crap-shoot if you can find one that has the ability to enable that capability on the card.

HD video streams could potentially benefit from Jumbo frames, but I'd not go there.  The real benefit would come from upgrading to gigabit.

Author Comment

ID: 20387092
K. I'll just go with the gigabit option.  I'll just purchase a managed gigabit switch & gigabit cards.  I should be all set to go.  Any suggestions on setup?

Expert Comment

ID: 20387118
If you're on a budget at all, you could check out the Dell managed switches.  They generally tend to be a good value and you can get redundant power if that is a concern.  Cisco switches are great but generally over priced and maintenance is expensive on them.  Broadcom also seems to be a good value for server nics, although I think Intel's are the best but a little more expensive.

What type of recommendations were you thinking of?

Author Comment

ID: 20387154
this is a first for me.  so I'll look around on dell.

Expert Comment

ID: 20417755

Just sharing my experience. If you do not have much budget on it.
As what I know, D-Link, 3Com, SMC have the lite switch for those SMB customer.

My office is using SMC8024L2 which is the lite switch model for SMC brand.
It got the features that I want.

The  things that  i implement in the office:

I bought 2 switches and linked up using LACP which increase & off load the traffic between switches.
I separate out the Office User VLAN and Guest VLAN but both able to surf internet.
Configure the Jumbo Frame on those Gigabit NIC connection.
It got the QoS function but i really do not know how to configure it. Anyway, my office do not have VoIP so that I think i do not need it.

The switch running perfectly for me.  

Just sharing my thought.

Hope it helps.


Author Comment

ID: 20418966
Since I don't need the jumbo frames.  I decided to go with the WRT350N.  I already have WRT300N.  350N, has the giga ports that I want.  It also has the usb port.  I'm going to attach a Drobo to it.  Idiot proof and super easy to implement.  Thanks guys for all of your suggestions.  

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