Wrt600n mtu above 1500 / jumbo frames?

hi, i've been playing around with my environment to try and increase speeds and have started to modify and test jumbo frames / MTU. according to the WRT600N manual, the recommended mtu size is between 1200-1500, but can be changed when changing from auto to manual.
only one problem with that, when i switch it to manual, and try and do anyting above 1500 a dialogue box pops up and says "the mtu size must be bewteen 576 and 1500". i did a quick search on the forum, and didn't see anything related to this.
has anyone else ever tried to talk to support and see if this is something that can be increased?
Message Edited by d-rick on 04-19-2009 09:36 AM

yeah, i actually talked to support and they told me the same thing. just another example of misleading information from Linksys as here is what the manual and the help page say:
MTU
MTU is the Maximum Transmission Unit. It specifics the largest packet size permitted for Internet transmission. Select Manual if you want to manually enter the largest packet size that will be transmitted. The recommended size, entered in the Size field, is 1500. You should leave this value in the 1200 to 1500 range. To have the Router select the best MTU for your Internet connection, keep the default setting, Auto.
no where in that description does it say that 1500 is the maxmium.
because this is also a gigabit switch, one would expect that jumbo frame support is not out of the realm of possibility. as a point of reference any other $50 (or less) gigabit switch supports this, but that's what i get for expecting too much from Linksys.
thanks for the info.

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FTTH connection proper MTU Size and Jumbo frames

I've recently moved to a ISP that provides a 4mbps connection through FTTH(Single OFC). There is a EPON ONU in my premise from which a RJ-45 lan cable is connected to my Intel DH67CL1 board based PC. manual says, the NIC is a gigabit ethernet card. I tried setting MTU of 8996 and I can ping and browse fine. But, I'm totally in dark whether this value is optimum and works flawlessly browsing sites. How to find and set the proper MTU for a fibre network like this? Is the value correct?
I tried like this decreasing mtu value:
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SIOCSIFMTU: Invalid argument
then,
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^^^ No error message and it seems accepting.
BTW, from arch wiki, I saw that the driver module(e1000e which is used here) used by NIC have some bug report filed wr.to Jumbo frame. Am I doing things correctly? Earlier MTU was at default 1500. Please guide. thank you
Some drivers will prevent lower C-states
Some kernel drivers, like e1000e will prevent the CPU from entering C-states under C3 with non-standard MTU sizes by design. See bugzilla #77361 for comments by the developers.
https://wiki.archlinux.org/index.php/Ju … mbo_frames

yeah, i actually talked to support and they told me the same thing. just another example of misleading information from Linksys as here is what the manual and the help page say:
MTU
MTU is the Maximum Transmission Unit. It specifics the largest packet size permitted for Internet transmission. Select Manual if you want to manually enter the largest packet size that will be transmitted. The recommended size, entered in the Size field, is 1500. You should leave this value in the 1200 to 1500 range. To have the Router select the best MTU for your Internet connection, keep the default setting, Auto.
no where in that description does it say that 1500 is the maxmium.
because this is also a gigabit switch, one would expect that jumbo frame support is not out of the realm of possibility. as a point of reference any other $50 (or less) gigabit switch supports this, but that's what i get for expecting too much from Linksys.
thanks for the info.

Mid 2010 Macbook Pro - Change MTU size kills internet (Jumbo Frames)

Hi everyone, i'm hoping someone here can enlighten or help me solve my problem I'm having.
I am trying to change my MTU size to enable Jumbo frames on my 13 inch Mid 2010 Macbook Pro. I recently bought a ReadyNAS Ultra and would like to speed up transfers to the unit.
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asdftroy wrote:
If you did read my post then you would have saw that the option is there, but that is not entirely what my inquiry is about. The option isn't working as intended, and I was wondering if anyone had the same issues as me. Thanks anyways.
Anyone else?
The way you responded to someone trying to help you probably means others will be hesitant to try.

Adjust MTU on my Time Capsule to enable Jumbo Frames?

Is there a way to adjust the MTU setting on my Time Capsule to enable Jumbo Frames? I have the most current Airport Utilities and firmware on my TC.

There is no way to adjust MTU on either WAN or LAN ports on the TC. At least AFAIK.. Apple do not allow users to access that depth of control.
Get a gigabit switch and plug everything into that if you want jumbo frames for local network.. Jumbo frames will obviously cause slow down on the router to the internet and I guess is why Apple doesn't use them.

Enable jumbo frame on Nexus switch

I read following phrase in configuration guide of Nexus 5020
The Cisco Nexus 5000 Series switch is a Layer 2 device. This means it does not fragment frames. As a result,
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Has anybody configured jumbo frame with above mentioned way ?

Yes, it looks something like this:
policy-map jumbo
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policy-map class-default
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service-policy class-default

No jumbo frames between 4500-X and Force10

Hi,
We have just installed new Cisco 4500-X 10Gbe SFP+ switches.
We have Dell Blade Chasis with Force 10 MXL blade switches.
We are testing/preparing the environment before our new Dell compellent hybrid arrays arrive, but we face a problem with Jumbo frames between the Cisco 4500-X and the Dell Force10.
When I do a ping -L from the blade server to a host connected to the Cisco 4500-X anything bigger then 1472 bytes seems to get dropped.
When performing a ping between servers connected to the 4500-X I can use jumbo frame sizes like 9000 without issues
When performing a ping between servers in the blade chassis I can use jumbo frame sizes like 9000 without issues
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Aggregates, VLAN's, Jumbo-Frames and cluster interconnect opinions

Hi All,
I'm reviewing my options for a new cluster configuration and would like the opinions of people with more expertise than myself out there.
What I have in mind as follows:
2 x X4170 servers with 8 x NIC's in each.
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igb0 device in aggr1
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igb3 stand-alone device for iSCSI network
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For 1) the question is really "Do I need to enable Jumbo Frames if I don't want to use them (neither public nore private network)" - the answer is no.
For 2) each cluster needs to have its own seperate set of VLANs.
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Why does iMac (Mid 2012) not support Jumbo Frames?

Why is it not possible to change MTU size to more than 1500? Buying such a high quality product, I would expect that it supports jumbo frames!
My NAS supports jumbo frames, the Air Port Extreme does but a brand new iMac doesn't???
Is there any patch or somethin to fix this?
Thanks!!!

Hi Marcus,
I find conflicting info on this...
The Ethernet port supports the configuration of Ethernet frames larger than 1,500 MTU (Maximum Transmission Unit).
http://support.apple.com/kb/HT4619
Can anyone confirm if the new 2011 imacs already support jumbo frames? I heard it now uses a new broadcom ethernet chip that now supports jumbo frames on the 21 inch model. They removed jumbo frames support in the previous i5 and i7 models...
Hmm, I remember that the iFix tear down revealed that the 2011 iMacs had a Broadcom BCM57765B0KMLG Eithernet chip. (just go to the page and if you are using safari/firefox press command + F and type "Broadcom" to jump to that particular)
http://www.ifixit.com/Teardown/iMac-...eardown/5485/2
so I did a little googling and found out that:
http://www.broadcom.com/products/Eth...lient/BCM57765
Integrated 10/100/1000BASE-T transceiver with:
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- Compliant with IEEE 802.3az draft standard for Energy Efficient Ethernet™ (EEE)
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- EthernetAV protocols with IEEE 802.1AS, 1588-2008, IEEE P802.1Qat and IEEE P802.1Qav support
So it should support Jumbo Frames.
http://www.philmug.ph/forum/f23/new-imac-early-2011-sandy-bridge-processors-7106 4/index8.html
Originally Posted by mpe
At least mine doesn't
Weird. My 27" 3.1GHz iMac that was delivered yesterday supports jumbo frames fine. I was quite concerned that it wouldn't because I rely on them for good performance with my NAS
I set it using System Preferences -> Ethernet -> Advanced -> Ethernet -> Configure Manually.
I've confirmed the setting by checking the output of ifconfig. It shows an mtu value of 9000.
http://forums.macrumors.com/showthread.php?t=1148176
Some of the 2010 iMacs did not I read.

Adding jumbo frame support into an existing Ethernet network

I have a remote site with 40 users that connect back to our main site via two point to point T-1s. These users connect to an Exchange server (DMZ), Sybase databases on Sun servers (Internal network), and access the Internet via the main site.
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I would like to enable jumbo frame support on these devices since they transfer hundreds of gigabytes of data on their local network. But if I do this, what will be the affect when they attempt to visit web sites or connect to the Exchange server?
How have you guys worked with this type of scenario?
The address space for this site is a /25 of one of our class Cs.
Please see the attached Visio diagram that outlines the connection points throughout the network.
Thank you

Best practice here is to segment your Jumbo Frame servers on their own VLANs for Jumbo supported systems only.
As a post here has already mentioned, Path MTU discovery will tell the systems on the Jumbo VLANs to keep the frames under 1500 when talking to a non-Jumbo VLAN.
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2970/12225see/scg/swint.htm#wp1154596
Please rate all helpful posts.
Brad

Is it possible to enable jumbo frames on vmxnet3 under Solaris 10?

Solaris 10 10/09 running on ESX4. VMware tools are installed. ifconfig vmxnet3s0 mtu <value> only works for mtu values of 1500 or less. /kernel/drv/vmxnet3s.conf gives no hints related to jumbo frames.
I've come up empty searching the net. Ideas?

According to this, it looks like you have to set the host for jumbo frames (which makes sense), then set the guest to use it, then set the guest OS to use it...

Macbook pro late 2008+jumbo frames

Hello
I've just got a buffalo duo nas server, and im not that happy about the speed..
Now, i know it supports jumbo frames, so my question is, does the Macbook Pro late 2008 support jumbo?
When im looking in the network settings i can manually set the ethernets mtu to 9000, but the airport is only at 1500 (cant be changed)
If the macbook supports JF:
Is there anyway i can get the airports mtu at 9000, or do i need another router.

there is no need to change the MTU. are you using wired or wireless connection to connect to yours nas server?

Jumbo frame ethernet

I came across a number of articles relating to jumbo frame gigabit ethernet and integrating into existing networks with fastethernet and 1518 frame size gigabit ethernet devices. Heres a quote i'd like to discuss...
"Today, however, applications optimized for large frame sizes can easily be integrated with existing Ethernet LANs without causing interoperability problems. For example, you can partition a logical network in which systems can exchange Jumbo Frames and mark them with IEEE 802.1Q virtual LAN tags. The extended frames will be transparent to the rest of the network.
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Are there any plans to upgrade the IOS to support configuring jumbo frames on per VLAN basis. Jumbo frames are an important issue to us as we can benefit from the performance increases and the improved server CPU utilization. Any thoughts ?

Best practice here is to segment your Jumbo Frame servers on their own VLANs for Jumbo supported systems only.
As a post here has already mentioned, Path MTU discovery will tell the systems on the Jumbo VLANs to keep the frames under 1500 when talking to a non-Jumbo VLAN.
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2970/12225see/scg/swint.htm#wp1154596
Please rate all helpful posts.
Brad

Airport Extreme with Gigabit Ethernet - Does it have jumbo frame support?

Please, can I get definite answer to this question? I do not need speculations as I read some reviews already. Can we have Apple finally put complete specification of the product rather than "popular one" with attachement of protocol numbers?
I just need simple answer possibly from Apple engineering team to the following questions:
1. Does current Airport Extreme have support for jumbo frames (everything above 1500bytes per frame)? (if one does not know what that is them perhaps understanding acronym "MTU" can help a bit)
2. If there is support then what is the maximum supported size of jumbo frame? (Some products do not go above 6k and I read some statistics that traffic somwhere is usually 66% at about 4k jumbo frames and above that there is not much...)
3. If there is no support then does Apple plan on update for this (firmware or hardware) in the future?
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I just need reliable answer by product specification that should be on paper at Apple, but it is not so I hope that one of guys here has access to some engineering team.
Thank you,
Maciek Samsel

The spec. on the chip used by Apple support your conclusion.
BCM5395 Features
Complies with IEEE802.3, IEEE802.3u, IEEE802.3ab standards
5 10/100/1000Mbps Auto-Sense RJ45 ports supporting Auto-MDI/MDIX
All ports Support Full/Half Duplex transfer mode for 10/100Mbps and Full Duplex transfer mode for 1000Mbps
Port-based and MAC-based VLAN
IEEE 802.1Q-based VLAN with 4K entries
Port-based rate control
Port mirroring
Compact field processor (CFP)
512 rules
Filtering, classifications, remarking, and priority actions.
Priority modification on egress
DOS Attack Prevention
Loop detection for unmanaged configurations with Broadcom’s patented LoopDTech™ technology
CableChecker™ with unmanaged mode support
Double tagging
IEEE 802.3x programmable per-port flow control and back pressure, with IEEE 802.1x support for secure user authentication
4K entry MAC address table with automatic learning and aging
128-KB packet buffer
128 multicast group support
Jumbo Frame support up to 9728 byte

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hi Harold,
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Strange... it's even given as an example here: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/15-1-2/XE_340/configuration/guide/config/sw_int.html#pgfId-1068699
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Wrt600n mtu above 1500 / jumbo frames?

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