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xabba

join:2001-09-26
Pinnacle, NC

Linksys BEFSR81 Router: MTU Settings

I have a Linksys BEFSR81 and cannot find the setting to change the value of the MTU. Im not sure if the latest firmware has the ability to change this. On DSLR's Tweak test, it says to raise my MTU to 1500. I did this in Dr. TCP and it still keeps saying this. I have restared after I used Dr. TCP and verified that it still said 1500 in the MTU box. I am having a feeling that it is the router, but on Linksys website, it says only upgrade firmware if your having problems with the router or you might damage it. I was wondering if the new firmware DOES provide the ability to change the MTU setting and be sure that it won't harm my router. My current firmware is: 2.38, Jul 03 2001. The latest firmware is: 2.40.2, Nov 07 2001. I've looked all over Linksys's site and have found nothing. Thanks for all of your help in advance!

-Justin


jnewby

join:2001-02-17
Cleveland, OH

Justin - go to »ftp://ftp.linksys.com/pub/befsr41/
and get the befsr81-204 file there.

Then you'll have it.

John N.



FROSTY
Premium,MVM
join:2000-08-10
Leeds, AL
reply to xabba

Actually, the file is named befsr81-fw2402.zip

Here is the correct link to download 2.40.2



xabba

join:2001-09-26
Pinnacle, NC

Are you sure that this firmware update gives me the ability to change my MTU setting and will not damage the router?

-Justin



FROSTY
Premium,MVM
join:2000-08-10
Leeds, AL

Yes, I use this router, the BEFSR81, with 2.40.2
Works great, practically flawless.

The 2.40.2 firmware has the MTU, SPI, port triggering, and other features found in the 1.40.2 firmware for the BEFSR11/31/41.

I still have my BEFSR11 and 8 port switch, but prefer using the BEFSR81 simply because it's 2 devices in one.



xabba

join:2001-09-26
Pinnacle, NC
reply to xabba

I just wanted to say thanks! After the firmware update I was able to change my MTU to 1500. Now on the tweak test it says ":) Looking Good" for the MTU speed. Now with the SB4100 Firmware upgrade, the Linksys Firmware upgrade, and the CableNut tweaker, I'm getting speeds off the OOL test server of around 740KB (@ 50% of D/L complete)!!! Before any of these tweaks I was getting around 315KB. A great big thanks to FR0STY, JoshNJ, Engineer88, jnewby, and howie1253!

-Justin (Thanks again for all of your help guys!)



bichi
Premium
join:2000-08-18
Denver, CO

reply to xabba

Ooops! ya did it already! Congrats!

Confirming Frosty's input.
I also use the LinkSys BEFSR81 8-port NAT Router.
Version 2.40.2 does allow you to change MTU values + new features. v2.40.2 has been stable for 2 months for me.

About your comment about "damage the router:"

RTFM - (read the f**king manual) - applies to ANY firmware flashes.
- hardcopy all current settings BEFORE you flash.
- hardcopy of flash procedures, in case you need to refer to "back-out" steps.
- confirm you are using the latest flash utility.
- try to have a copy of working firmware rev or make a backup copy during flash.
- make sure all you connections and network elements are stable.
- configure an alternate Internet access connection.
(dial-up, in case you need Internet Access to ask or look for help)

I have flashed LinkSys BEFSR41,81 and EFSP42 MANY times in the past 2 years and never had problems.

Take a look at the LinkSys BEFSR81 page. It also has flash guides and notes:
»www.linksys.com/download/firmware.asp?fwid=5
[text was edited by author 2002-02-23 16:15:59]


dracko712

join:2002-02-24
Whittier, CA
reply to xabba

Has anyone noticed their dsl connection dropping with version 2.40.2?

Even with keepalive enabled and disconnect at 0 minutes my IP keeps changing once an hour or so.... rolling back to 2.8 works, but then I have other issues with that firmware version and posting to usenet...

All this on earthlink dsl via verizon



KAIFS
V I P
Premium,MVM
join:2001-01-11
CHEEEESE WI
reply to xabba

No problems here with disconnects at all, in fact we are one of the favorites on MusicCity with 100+GB of goods available on my wife's PC 24/7:)
--
..MISTAKE RECOGNIZED IS HALF CORRECTED..


jnewby

join:2001-02-17
Cleveland, OH
reply to xabba

No problems here whatsoever with 2.40.2. set for keepalive, redial 20 secs., for Ameritech DSL.

John N.


Don_Young

join:2001-02-20
Shreveport, LA
reply to xabba

I upgraded my firmware to the 2.4xx on my Befrs8 port router, however it still will not let me change the MTU to 1500. It says the max is 1492 when I try to change it to 1500. Any ideas? Thanks, Don



pplchamp1
Great One
Premium
join:2002-01-25
East Hartford, CT
reply to xabba

The max on DSL is 1492 (accounts for 8 bits of overhead) from what I have read.


mfortunato

join:2002-03-16
Thousand Oaks, CA
reply to xabba

max is 1492 if you are running pppoe


Chastan

join:2002-02-10
Pleasant Hill, CA
reply to xabba

I had the 2.40.2 firmware installed, and the router would occasionaly "crash" (Diag light staying on constantly). Although I lost some functionality, I downgraded to 2.38.whatever and it's been stable.


RobertKop

join:2000-09-22
Milwaukee, WI

I am having the same trouble with my BEFSR81, v. 2.40.2. It starts up fine, but every now and then the DIAG LED comes on and I need to reset the router, then things work fine. I wonder if this is the firmware or something to do with Windows XP. It seems that I may need to revert to an earily version of the firmware as well.
[text was edited by author 2002-03-18 13:29:53]



FROSTY
Premium,MVM
join:2000-08-10
Leeds, AL

reply to Chastan

Odd.
Your router probably didn't take the 2.40.2 firmware correctly.

If you want to use 2.40.2, try the following:

Download 2.40.2 again.
Reset the router to factory defaults
Cycle power on the router.
Flash router to 2.40.2
Cycle power again on the router.
Reset to factory defaults again
Cycle power one more time.
Proceed to log into router and set it up.
Reboot router before use.

I have yet to experience such a lockup problem and I have used the router with Win 9x, 2K, XP, and Linux with no problems.

Are you using cable or DSL?
Are you changing the MTU option to an odd MTU value?

If your router continues to hang with 2.40.2, then either the router is bad, or a configuration error in causing the crash.

[text was edited by author 2002-03-18 13:49:59]


RobertKop

join:2000-09-22
Milwaukee, WI

Frosty,

Thanks for the suggestion. I have reset and flashed my router as you outlined. It's too early to tell if it has worked. Also, I have DSL (ADSL) through, Telocity/Directv with Ameritech as the last mile service provider. And I have not tried to alter the MTU on the router, the setting is currently disabled. (I don't know if this means anything.)


mfortunato

join:2002-03-16
Thousand Oaks, CA
reply to mfortunato

I am using BEFSR81. I cannot set the MTU on my pc higher than 1400 without problems. I assume that the router is limiting this. I see that you can change this with the 2.40.2 firmware (which I have). Do I just go in there and set it to 1492 (Earthlink requires pppoe) and then adjust it on my PC as well?

thanks. by the way, you can kill one of these while flashing the firmware. I had tried to flash my unit with the new firmware following all of the admonitions and recommendations here and at Linksys. the flash download failed and the unit was DEAD (blinking diag lite).. I called linksys, we tried a few things with no luch, and they said I had to exchange the unit. I have NEVER heard of a device that could die upon flashing firmware. I am an electrical engineer and have been involved in the design of many flashable products. We always made sure that under any circumstance the unit would at least have enough intelligence to download new firmware no matter what happened during a failed download. it is not that difficult.


Krozar7

join:2000-06-29
Meridian, ID
reply to RobertKop

I also experienced this same problem. Mine would crash every 1 - 2 days. I reflashed the firmware several times, but the problem still kept occuring. I finally flashed backward and the problem has not presented itself again in 6+ weeks. I think there may be something in 2.40.2 that causes the crash. I am waiting for the next firmware release to come out. If anyone knows of a beta firmware out there, let me know.



KAIFS
V I P
Premium,MVM
join:2001-01-11
CHEEEESE WI
reply to xabba

I am fine with 1492 on PPPoE ADSL


Yudsky
Premium
join:2002-03-02
Marietta, GA
reply to xabba

My default has Block WAN Request enabled and Remote Management and Upgrade disabled, should I change these settings?



RWL

join:1999-07-24
Bellflower, CA

reply to Krozar7

Had the same problem, linksys exchanged the unit (it was less than year old. Now runs 24/7 without resets.
v2.40.2 firmware, pppoe enabled, mtu set at 1492

New unit has small power transformer.
[text was edited by author 2002-04-03 23:58:38]


mfortunato

join:2002-03-16
Thousand Oaks, CA
reply to Krozar7

I had a different problem. The unit was dead immediately upon a failed attempt to download the new firmware. It would not accept a download of any firmware after that no matter what.


mfortunato

join:2002-03-16
Thousand Oaks, CA
reply to KAIFS

I have set my router to 1492 but I still can't set the pc's MTU above 1400 without problems (as determined by ping -f -l). Could this be my ISP?


mfortunato

join:2002-03-16
Thousand Oaks, CA
reply to RWL

That was my solution as well. I wonder if they would still do this after one year? after all it is a latent defect that the device can die upon an attempted firmware download.


mfortunato

join:2002-03-16
Thousand Oaks, CA

Can someone explain this. As stated before, I have set my BEFSR81 to MTU=1492. I also set the MTU for my NIC to 1492 but, using ping -f -l found that I could not go above 1400 without fragmenting.

Today I checked out my wife's OLD computer and found that teak tests said it was running at 1492. I thought that was funny since I had never changed any of the registry settings. Tweak tests also said that RWIN = 10164 which is exactly 7 x the MSS. I ran DRTCP and it reported the MTU and RWIN as being blank!?!? so somehow that machine KNEW to use 1492 (i.e. optimal) and 7 x the MSS for RWIN?!?!?

So I ran back to my relatively new and way more powerful machine. I ran DRTCP and deleted the RWIN and MTU fields. I rebooted and pinged and found that I still could go no higher than MTU=1400. I ran tweak tests and, guess what, it reported MTU of 1400 and RWIN of 9520 - exactly 7x the MSS. I ran DRTCP again and MTU and RWIN are blank.

So what is going on here?

Why do both machines "KNOW" to set the MTU and RWIN where they do? (note her machine runs win98 and mine runs 98se)

Why does my machine seem to limit MTU to 1400?

I would appreciate any inputs.



Ed Wilts

@merrillcorp.com
reply to Krozar7

I too have had repeated lockups with 2.40.2. Diag light comes on and the unit is not even pingable from the inside. A quick reset (power off/on) will get it going for another day or two. I've been working this with Linksys for a few weeks, and they finally decided that my unit was bugsted and to send me a replacement. It arrived today so I'll install this weekend and see what happens.

.../Ed
mailto:ewilts@ewilts.org


chadwick8

join:2002-04-17
reply to RWL

I've had similar problems with BEFSR81 units resetting.

I'm on my second unit now. Both exhibited identical behavior in my environment. Every "so often" (not on periodic intervals) the router resets. The front panel goes through the full power on self test routine, and it continues on happily afterwards.

The only reason the user notices usually is that the DNS server it returns on the initial DHCP request is 18.234.0.0, so nothing works until you request a DHCP address again.

I would have assumed just bad hardware, and I did with the first unit. It's remarkable that the second unit is exihibiting the same behavior. Hmmm...

Re-flashing of the unit to 2.42.2 has made no difference. I haven't tried downgrading the firmware yet.

I make heavy use of Windows XP on my LAN. I'm wondering of the XP machines are broadcasting UPnP requests and causing the router to crash?

Kind of a bummer. I've been using the BEFSR41 for months happily, but I wanted the SNMP support so I could run mrtg.



FROSTY
Premium,MVM
join:2000-08-10
Leeds, AL

Something I've noticed with these SR81 routers.

I've heard this 'reboot at random' is a sign of a faulty router.

I believe the source of the problem is a faulty power supply.
Here's proof to back up this theory.

I had the same problem with an older 8 port Linksys switch (the big clunky white one). It kept rebooting at random and I was beginning to think the switch was burning out. Turned out to be the power supply!!! Believe it or not, the SR81 power supply is the same model as the power supply for this 4 year old switch!!! Both power supplies have the same input and output power ratings.

I took the old power supply for the old switch and hooked it up to my SR81. The SR81 started rebooting constantly to the point where the orange DIAG light stayed solid. At the same time, I hooked the SR81's power supply to the old switch and it worked flawlessly. I switch the power supplies back, and the SR81 works flawless while the switch reboots constantly.

Even a Fluke 87 multimeter revealed the older power supply's DC voltage was not consistent. Thus causing the problems.


mushx

join:2002-03-17
Huntington Station, NY
reply to xabba

i have same problem w/ DIAG organe light. It happens in random times? anyway to get old firmware?