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Beginner

887W jumbo frame?

Hi, I would like to know how to get 4088 byte jumbo frame support on the four LAN 10/100 ports. This is a ADLS2+ unit, so it would need to have MTU 1500 on the WAN port.

Any help greatly appreciated.

regards, Mark

29 REPLIES 29
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mgregory@agama.com.au

Hi Jon,

as I mentioned with jumbo frames set on all devices I get up to 25 Mbytes per second around my network. Now I'm back to the 1-2 Mbytes per second that is possible when frames are set to mtu 1500

I could not recommend any solution today that does not include support for 4088 byte or 9016 byte jumbo frames.

Yet, I have been silly enough to purchase the 887W without noticing the lan ports were 10/100 - I just could not imagine a company selling 10/100 today and this is my excuse for not noticing - and yeah I'm shocked now as I believe the 887W to be a really poor product that seems to be a marketing exercise.

regards,

Mark

Mark

I bought the 887W because it includes 802.11n v2 - therefore it is reasonable that it will operate at max speed and talk to other devices at a reasonable speed.

I think it would be reasonable to expect it to be fast for communication between devices in the same wireless vlan. But as soon as you go through the router you are now facing the bottleneck of throughput between interfaces on the router.

What surprised me was when you said you could get 100Mbps from the wlan to the a device on the internal LAN ie. via the 877. The 877 can support nowhere near 100Mbps throughput so perhaps i am misunderstanding the architecture of the 877 in terms of how the wlan interface and the inbuilt LAN interfaces work. I would have thought this communication would be limited by the overall throughput of the 877 but from what you say it seems not.

Have i misunderstood what you have said ?

It's important to understand because if the communication between the wlan and inbuilt LAN interfaces is limited by the overall throughput this will have a big impact on the cost of "one box" solution ie. the router is you choose is going to have to support at least 300Mbps throughput.

It's late here in the UK but i'll check back to this thread tomorrow.

Jon

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Hi Jon,

I have not stated that I had a 877. Previously I had a 837 -> pix 506E -> HP procurve 24 port 1000mbps

Conneted to the procurve I had a separate 802.11n v2 access point. All my LAN devices were connected to the HP procurve.

All devices on the network were set to jumbo frames

I had excellent throughput around my LAN. Now it is back to 1500 mtu and I feel like I'm back to 1990.

regards,

Mark

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mgregory@agama.com.au

Hi Jon,

I have not stated that I had a 877. Previously I had a 837 -> pix 506E -> HP procurve 24 port 1000mbps

Conneted to the procurve I had a separate 802.11n v2 access point. All my LAN devices were connected to the HP procurve.

All devices on the network were set to jumbo frames

I had excellent throughput around my LAN. Now it is back to 1500 mtu and I feel like I'm back to 1990.

regards,

Mark

Mark

Sorry, i meant 887, it was quite late, although i would have thought you could have worked that out

We seem to be talking at cross purposes here.

The 880 series routers support up to 25Mbps throughput of CEF switched traffic. Forget jumbo frames for a minute. What is the maximum throughput you have achieved between a wireless client on the new 877 and a device on the internal LAN ?

Jon

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hi Jon,

were off track here. My concern is not the wireless - it appears to work correctly. The issue is the 887W not having 1000 Mbps LAN switch ports. Nothing can overcome this limitation.

What has happened is that a number of my NAS stopped working. It was only when I moved everything on the LAN back to 1500 mtu that my network started to work again.

Without going around in circles, I'm after advice on a device that will do what I need and can overcome the 887W limitations - which appear to be considerable.

regards, Mark

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Mark

Where i am confused is when you say -

as I mentioned with jumbo frames set on all devices I get up to 25 Mbytes per second around my network

and you seem happy with that. Now do you mean your internal network because if so you why on earth do you need 1Gbps interfaces ?

I think we have got off track, so to try and get back on track -

1) what speed are you looking for in your internal LAN. And by this i don't mean from external to internal, i simply mean within your LAN

2) what speeds are you looking for from external to internal ie. via WAN/VPN etc.

3) what speeds are you looking for between wireless and internally wired clients

what i am trying to explain is that 887 can support a maximum of 25Mbps throughput. Anything that goes through the 877 will be limited by this.

Jon

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Hi Jon,

thank you for your input. I don't believe this is a a suitable location to explain to you how jumbo frames speed up a network. I mentioned on my LAN with Jumbo Frames I'm getting 25 Mbytes per second and now without I'm getting 1-2 Mbytes per second. Isn't that clear enough.

The 887W LAN switch has nothing to do with internal to external speeds in my discussion.

The 887W wireless access internal interface is gigabit - yes, login to your device and check it out. It has to be gigabit to support the 300 Mbps standard for 802.11n v2

I would appreciate your help identifying a suitable device or please move on to another thread as I have stated and restated what I'm after.

regards

Mark

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mgregory@agama.com.au

Hi Jon,

thank you for your input. I don't believe this is a a suitable location to explain to you how jumbo frames speed up a network. I mentioned on my LAN with Jumbo Frames I'm getting 25 Mbytes per second and now without I'm getting 1-2 Mbytes per second. Isn't that clear enough.

The 887W LAN switch has nothing to do with internal to external speeds in my discussion.

The 887W wireless access internal interface is gigabit - yes, login to your device and check it out. It has to be gigabit to support the 300 Mbps standard for 802.11n v2

I would appreciate your help identifying a suitable device or please move on to another thread as I have stated and restated what I'm after.

regards

Mark

Mark

I don't need you to explain how jumbo frames speed up things, i do, although you act as though as i don't, have some network experience however limited you seem to think that is.

You still have the procurve and it is connected to the 887. And then you say you are not interested in external to internal. So how does the 887 affect that. If it is internal why go to the 887, unless either -

1) you are routing vlans off the 887 which you have made no mention of so far

or

2) it is the wireless to LAN traffic but you have already said that is not a concern

or

3) you have other devices connected into the 887 switch which again you have made no mention of

So my question was exactly how is the 887 messing up the LAN as the LAN so far as you explanation has gone is contained with the Procurve. So for a LAN device to talk to another LAN device why does it have to go via the 887 - can you not understand why i am confused ? Unless there is something missing from your explanation ?

Why not simply configure the port connection from the procurve to 887 to not use jumbo frames, after all you don't care about LAN to external ?

Now i have also pointed you to the product pages for possible replacements but apparently you don't want to do that work yourself.

I have continually asked you the same question in any number of different ways but you still haven't explained it clearly. The reason for all the questions was to try and make sure i didn't recommend an unsuitable device only for you to purchase something which still didn't work.

Obviously it is me, not you, although in my defence i don't seem to have this problem with any other posts on these forums. So rather than you continuing to patronise me, yes it probably is best if i move on to other threads.

Jon

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Jon - for the record the lan switch interface (which the wlan is connected to via an internal gigabit interface) on the 88X series are NOT limited to 25Mb/s and can switch at wire speed.  I recently had an 881W and would regularly get 70-80Mb/s transfer rate from lan to wlan on 2.4Ghz N, and 90Mb/s lan to lan.  The 25Mb/s number you're referring to is the speed at which it can switch packets between its two routed interfaces (lan to wan, although the number will vary drastically depending on what services are enabled and packet size).

Mark - I recently went though the exact same process as you in consolidating my networking devices.  I ended up getting a cisco 1941 with an hwic-1adsl and am going to put the 8-port gigabit poe double-wide ehwic switch in also (there is also a 4-port version).  I didn't get the "W" version and still use a separate wireless access point because I expect this router to last me longer than wireless-n will be around and I want to be able to upgrade my wireless accordingly.  Expensive, yes, but basically I found that there is no cheaper Cisco alternative for an all-in-one gigabit setup.  There are several much cheaper, consumer based routers which fill your requirements though and I can point you in the right direction if you want...although they don't run ios. 

Eric

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Eric

Jon - for the record the lan switch interface (which the wlan is connected to via an internal gigabit interface) on the 88X series are NOT limited to 25Mb/s and can switch at wire speed.  I recently had an 881W and would regularly get 70-80Mb/s transfer rate from lan to wlan on 2.4Ghz N, and 90Mb/s lan to lan.  The 25Mb/s number you're referring to is the speed at which it can switch packets between its two routed interfaces (lan to wan, although the number will vary drastically depending on what services are enabled and packet size).

Many thanks for confirming this, very useful to know.

Where i was getting confused, and it could just be me , was from Mark's description he was happy with 25Mbps within the LAN but with the 887 he was down to 1-2Mbps. Now i understand the 887 was dropping the jumbo frames but i have run many gigabit networks (without jumbo frames) and with gigabit internally connected to 100 fast ethernet on the 887 you can do a lot better than 1-2Mbps or indeed 25Mbps. I suspect i may have misunderstood Mark but i was reluctant to recommend anything else before fully understanding the issue and jumbo frames seemed to be a bit of red herring.

Perhaps you read it differently ?

Jon

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Yeah I'm not sure what's up with the 25Mb/s and 2Mb/s lan switching speeds...sounds like something is definitely wrong somewhere else.  I'd suggest disabling jumbo frame support everywhere and see if you can get lan switching up to ~100Mb/s.  Even the 837 should be able to switch on the lan ports at near line speed.

...unless...are you doing vlan routing?

Eric

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hi Eric,

I also researched the 1941 and I was shocked at the cost - forget that idea - I seem to have already bought one paper weight.

I think there is a crossover between bps and Bps in my posts.

With jumbo I could get 25-50 MBytes per sec around my home network

Without jumbo I'm back to 1-2 MBytes per sec

This is the killer for the 887W as far as I'm concerned.

I'm really amazed that Cisco would sell a "new" product with the really poor features of the 887W. I paid about $1000 for a "new" Cisco 887W

I would appreciate knowing alternatives. I'm researching the chipset in the 887W - screw driver in hand - and I have a feeling that a "new" cheap device will have a much newer and more capable chipset than that in the 887W. I'm guessing it is the same chipset as found in the 877 and possibly even the 837.

I'm in Australia so it needs to support ADSL2+ and have a four x gigabit switch with jumbo frame support. If it does not have wireless N then I won't really care - though if I'm going for a cheap device then it should have wireless and VoIP support and be able to support more than one external WAN IP.

I'm not trying to make a big point - but I figure Cisco has maybe 5 years left if the Cisco management can't change their business model.

regards,

Mark

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Hi Mark,

When you're switching through the 887 with non-jumbo frame setup are you changing the mtu on your end devices back to 1500 (or disabling jumbo frame support)?  If they're still sending jumbo frames the 887 could either be dropping them or fragmenting them, resulting in your slow speed.  The 887 should be able to switch 10-12MB/s on the lan ports.  If it's not I would suggest that there is something wrong elsewhere in your setup as only 25MB/s on a gigabit switch with jumbo frames is quite slow as well. 

Just to reiterate and confirm what others have already said - it's almost universal that fast ethernet (100Mb) connections do not support jumbo frames, so the 887 is not cutting corners here as you seem to suggest.  The 887 is meant to be an edge device, basically routing stuff over a dsl connection, and one normally doesn't require this type of device to switch at gigabit ethernet speeds.  If you really need gigabit switching, just use a gigabit switch.  This isn't a cheap and nasty router and if you dig into what ios is capable of you'll find that it goes far, far beyond what cheap home routers with built-in gigabit switches can do.  Yes, some cheap routers might indeed route faster, but without many of the features.  It's analogous to complaining that an expensive tractor can't go as fast as a cheap car on the road.  Different classes of devices.

Just out of curiosity, why exactly do you need jumbo frame support?  I use gigabit at home and at work, and the only place I've enabled jumbo frames is in a link at work between some servers and some storage devices for long backup transfers (many terabytes).  Between fast computers without jumbo frame I get ~60MB/s transfer speeds and I'm pretty sure disk speed is the limiting factor here.  Jumbo frame support wouldn't make much difference in this situation except with a very fast disk array.

Here's a cisco small business router which I think has the specs you're looking for (netgear makes some similar type/price routers also): http://www.cisco.com/en/US/prod/collateral/routers/ps9923/ps9931/data_sheet_c78-496737.html

Not sure about jumbo frame support, but seriously, I wouldn't worry about it.  If you're only getting 25MB/s then you're not benefiting from it and you have other issues to sort out first.

Regards,
Eric

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hi Eric,

I'm sure I wrote the following in the message immediately prior:

With jumbo I could get 25-50 MBytes per sec around my home network

Without jumbo I'm back to 1-2 MBytes per sec

I am getting speeds higher than 50 MBytes per second for large video files.

As you would know the rates change depending on the traffic class.

Yes, when I disable jumbo - I mean I'm changing mtu back to 1500 on all devices.

I do not agree that the 887 is meant to be an edge device and that it should not support more than 100 mbps.

As I said earlier the 802.11n can do 150-300Mbps and therefore if a wireless device is trying to connect to a LAN server it cannot operate at the design specification for 802.11n

The 887W has a 4 port switch - if it was just an edge device it would not have a 4 port switch it would have one port like the PIX 506E for example.

If there are 4 switch ports there can be no excuse in the year 2010 to sell as new a device that provides 10/100 Mbps only.

thank you for the suggestions - I have been looking at several other vendors working out which one will do everything I need.

It is impossible to defend Cisco -you don't sell products with a poor feature set at a huge mark-up and expect customers to put up with it for too long.

I'm old enough to remember an array of companies that went down the same path that cisco has chosen. Look up Wang, Sun, DEC and so on.

I think this thread is about exhausted. I'll find a cheaper better solution and I thank you for your input.

regards,

Mark

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Mark

All everyone has being trying to do in this thread is patiently explain to you that the 887 is not designed to do what you want. But you seem to ignore pretty much everything people have said and just continued on the same line of argument.

You purchased the device without doing your research and then decided to come onto these forums and complain and argue with anyone who tried to help that the Cisco were crap and the 887 should actually do what you want it to do.

I suspect this will fall on deaf ears but here are some answers to your questions which may help with further purchases -

1) why does 887 support 802.11n which can support more than 100Mbps.

because the 887 has fast ethernet ports. If it supported anything less than 802.11n then the wireless would be the limiting factor. It is like buying a router with gigabit interfaces and then saying why have gigabit if it only supports 200Mbps throughput. The answer being because they don't make 200Mbps interfaces.

2) 887 is not an edge device.

You quote the pix 506 as an example of what is an edge device. But the pix 501 came with an inbuilt switch. Would you class that as a non-edge device because i wouldn't. The idea behind the 887 is to provide WAN connectivity for a small office. It just so happens to have a switch because the office may be small enough to only 4 users or less much like the pix 501.

But it was never designed to be used as a core LAN switch running multiple applications for internal users. Again, it comes back to wrong kit for your requirements.

You may not agree with any of the above as you have continually said in your other posts but whether you agree or not it doesn't change what the 887 was designed to do.

You yourself have readly admiitted you are a not a Cisco engineer and yet you seem to feel quite justified telling people who are Cisco engineers that they are wrong and you know better. I suspect a lot of this comes from simply buying the wrong device and needing to sound off to people about it but it is not very gracious to do that to people who are actually trying to help you.

Regardless, good luck with finding a workable solution.

Jon


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Hi Mark,

800 series routers are probably most commonly used for connecting small branch offices to a headquarters via vpn or provided as cpe for similar tasks, so gigabit really isn't necessary for their intended purpose.  Of course they're edge devices.  You're not going to use one to do internal routing.  It has a dsl port doesn't it?  The fact that it has switch ports means nothing - its a feature...look at the ASA5505.

Also just so you're aware, even the best wireless-n access points (ruckus, aironet - I have an 1142, etc.) will do 150Mb/s at best and a good one will do 100Mb/s.  So while you might not squeeze every drop of bandwidth out of one by connecting it to a 100Mb port, you're not really limiting them that much. Yes, theoretically the spec is 300MB/s but just as with wireless-g which is rated at 54Mb/s, a G access point will hardly ever go above 25Mb/s.

Good luck in your search.

Regards,
Eric