Choosing new WAN MAC address resolves packet loss and DHCP?

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bedouin
DD-WRT Novice


Joined: 20 Aug 2006
Posts: 9

PostPosted: Mon Sep 04, 2006 3:00    Post subject: Choosing new WAN MAC address resolves packet loss and DHCP? Reply with quote
I'm using a WRT54G v5 with DD-WRT v23 SP2 Micro and Comcast is my ISP. Yesterday I began to lose my Internet connection, where the only solution was to manually release and renew the DHCP lease from the router.

Wondering if there weren't other problems, I also pinged some Internet sites and noticed anywhere from 4-7% packet loss. I wanted to see if the issue was with my router, so I connected it directly to my PowerMac running OS X 10.4.7, and had 0% packet loss and no DHCP problems.

I tried a number of different things, including replacing the cat5 cable connecting my cable modem and router (it looked a little shabby), but that didn't work. What did resolve the issue was changing the WAN MAC address from DD-WRT Micro's default (00:40:10:10:00:02) to a MAC address I copied from an old D-Link router.

DD-WRT and the router have been performing fine for probably a month now. Any ideas why I all of a sudden had problems, and why changing my MAC address fixed it?
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Gawein
DD-WRT Novice


Joined: 31 Aug 2006
Posts: 4

PostPosted: Mon Sep 04, 2006 15:09    Post subject: Re: Choosing new WAN MAC address resolves packet loss and DH Reply with quote
bedouin wrote:
I'm using a WRT54G v5 with DD-WRT v23 SP2 Micro and Comcast is my ISP. Yesterday I began to lose my Internet connection, where the only solution was to manually release and renew the DHCP lease from the router.

Wondering if there weren't other problems, I also pinged some Internet sites and noticed anywhere from 4-7% packet loss. I wanted to see if the issue was with my router, so I connected it directly to my PowerMac running OS X 10.4.7, and had 0% packet loss and no DHCP problems.

I tried a number of different things, including replacing the cat5 cable connecting my cable modem and router (it looked a little shabby), but that didn't work. What did resolve the issue was changing the WAN MAC address from DD-WRT Micro's default (00:40:10:10:00:02) to a MAC address I copied from an old D-Link router.

DD-WRT and the router have been performing fine for probably a month now. Any ideas why I all of a sudden had problems, and why changing my MAC address fixed it?


I have this problem to,
bedouin
DD-WRT Novice


Joined: 20 Aug 2006
Posts: 9

PostPosted: Mon Sep 04, 2006 16:49    Post subject: Reply with quote
Can someone delete this topic? I didn't realize I stuck it in the wrong subforum until now.
vasillalov
DD-WRT Novice


Joined: 11 Sep 2006
Posts: 9

PostPosted: Mon Sep 11, 2006 5:25    Post subject: Reply with quote
Most probably its a comcast issue.
aceofspades
DD-WRT Novice


Joined: 18 Oct 2006
Posts: 1

PostPosted: Wed Oct 18, 2006 19:37    Post subject: Reply with quote
Had the same problem with a WRT54G v6 router. Cloned the MAC address and packet loss is gone. Thought it was my ISP until I connected my PC directly and pinged out for a few minutes without any loss.

I'm glad you stumbled on the fix. Thanks for posting it.
cdr127
DD-WRT Novice


Joined: 19 Feb 2008
Posts: 1

PostPosted: Wed Feb 20, 2008 22:42    Post subject: same problems for charter ISP Reply with quote
My router is dropping between 15%-35% at any given time. I have cloned the MAC from my MacBook Pro, because charter requires you to have a "PC" connected. 0% loss connected from laptop to modem.

Any Ideas
goobles
DD-WRT Novice


Joined: 05 Jan 2008
Posts: 2

PostPosted: Thu Jul 10, 2008 17:12    Post subject: Reply with quote
I just had a similar problem with my router (linksys wrt54g v6 - first it was running dd-wrt v23sp2, then upgraded to v24 before I figured out the problem). For some reason, my router was using a default MAC address of 00:40:10:10:00:02 for its WAN port. However, the symptom I was seeing was that my ISP's DHCP server would not give me an IP address. I noticed that when I hooked my laptop directly to the cable modem, it would give me an address every time. I finally saw that the MAC addresses looked a little generic and that sent me down the right path to fix the problem by using the clone MAC address feature to configure the MAC address from the sticker on my router (what it should have been all along).

It is no surprise that this would cause a problem. If there is anyone else near me in the network that is using dd-wrt with its default MAC addresses, whatever L2 equipment we connect to will be very confused to find that a particular MAC address appears in multiple places. It will probably be constantly updating its forwarding tables as it receives packets from each of the dd-wrt routers.

It would be a very nice improvement to somehow highlight the MAC address in the GUI and provide a message indicating that it should be changed to something that is less likely to collide.

Arthur
hpsenicka
DD-WRT Guru


Joined: 30 Jun 2008
Posts: 825
Location: near Toronto, Canada

PostPosted: Thu Jul 10, 2008 17:45    Post subject: Reply with quote
goobles wrote:
I finally saw that the MAC addresses looked a little generic and that sent me down the right path to fix the problem by using the clone MAC address feature to configure the MAC address from the sticker on my router (what it should have been all along).

It is no surprise that this would cause a problem. .......

.... It would be a very nice improvement to somehow highlight the MAC address in the GUI and provide a message indicating that it should be changed to something that is less likely to collide.

Arthur


I am very surprised that this is the default behaviour of dd-wrt.

I would have expected that the actual MAC address of the device would have been the default value used by dd-wrt, and I would be very interested to know why this is not the case!
goobles
DD-WRT Novice


Joined: 05 Jan 2008
Posts: 2

PostPosted: Thu Jul 10, 2008 23:54    Post subject: Reply with quote
I know that I did a hard reset on mine to recover from a lost password (which sets everything back to defaults). I do not recall, but it may be that I had my old MAC until then. It's also possible that the MAC addrs are stored in some vendor-specific place and the initial upgrade to dd-wrt does not have the logic to find that info for each supported hw platform. I'm just guessing, though. Either way, I still say it would be nice to highlight this condition if/when it occurs to encourage the user to put something less generic in place.

What MAC addrs is yours using? I think this is under the status tab somewhere.
hpsenicka
DD-WRT Guru


Joined: 30 Jun 2008
Posts: 825
Location: near Toronto, Canada

PostPosted: Fri Jul 11, 2008 1:29    Post subject: Reply with quote
Mine is using the same default MAC address as yours was.
redhawk0
DD-WRT Guru


Joined: 04 Jan 2007
Posts: 10941
Location: Wherever the wind blows- North America

PostPosted: Fri Jul 11, 2008 1:37    Post subject: Reply with quote
This is because you didn't build a custom vxworks_killer file when you initially flashed the router. V5 and V6 units will have a default MAC address (starting with 00:40:....if I remember right)

There are 2 ways to fix it perminantly

one is to revert the router back to Linksys firmware...then go through the flash process again using a customer vxworks_killer file.....

second is ask me nicely Laughing and I'll send you a new CFE file with your MAC address embedded...then JTAG it back on.

The only other option (but not perminant) is to set it manually in a startup script on the Administration>>Commands tab.

nvram set et0macaddr=<your mac>
nvram commit


redhawk

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hpsenicka
DD-WRT Guru


Joined: 30 Jun 2008
Posts: 825
Location: near Toronto, Canada

PostPosted: Fri Jul 11, 2008 2:50    Post subject: Reply with quote
Interesting that this affected my WRT54G v.6, but not my WRT54GL.

I haven't tried dd-wrt with my WRT54GS v.7 yet.... but it looks like I should expect a similar result as the WRT54G if I follow the same steps.
LLigetfa
DD-WRT User


Joined: 23 Oct 2007
Posts: 406

PostPosted: Fri Jul 11, 2008 2:57    Post subject: Reply with quote
hpsenicka wrote:
Interesting that this affected my WRT54G v.6, but not my WRT54GL.
The GL had linux originally, not VXWorks.
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hpsenicka
DD-WRT Guru


Joined: 30 Jun 2008
Posts: 825
Location: near Toronto, Canada

PostPosted: Fri Jul 11, 2008 3:00    Post subject: Reply with quote
DOH!

... well that was obvious, wasn't it!
nemesisdb
DD-WRT User


Joined: 10 Oct 2006
Posts: 195

PostPosted: Fri Jul 11, 2008 3:12    Post subject: Reply with quote
This is a related concern regarding my Buffalo G125. LAN MAC matches the default MAC label on the unit. WAN MAC has the final character changed from A to B and WLAN has the final A changed to C.

Just a thought, but for people with ISPs that care, shouldn't the WAN MAC match what's printed on the unit?
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