graffixjones
Nuttier than Squirrel Turds
join:2006-03-28
Chico, CA
| [General] BEFSX41 / Siemens 4100 DSL Modem problem and solution
This is more of an informative thread, that I figured I'd post in case anybody else runs across this problem. I fought this issue for about 16 hours, and finally stumbled upon the solution after hours of fruitless searching through several forums (including this one).
Anyway, the problem arose when I recently switched over to SBC DSL services from Comcast. SBC uses PPPoE rather than DHCP (like Comcast), and the Siemens 4100 modem is configured to initiate the PPPoE connection, and then feed a DHCP address to whatever device (whether it be a computer or router) that requests a connection.
The problem I was having, was that the router would successfully connect to the DHCP server on the modem, but after surfing to one or two websites (like two connections), the router would no longer communicate with the modem. The link would be dead (under this arrangement I was actually able to still 'see' the modem and able to log into it's interface when the connection was up, but when the communication stopped, I could not even connect to the modem interface).
Also, if the modem lost connection, it would lock up the router, forcing a hard reset (unplugging it).
I had used the BEFSX41 router with my Comcast DHCP connection without incident for almost two years.
What I finally did, was connected the modem directly to my host computer, and went into it's configuration menu (at 192.168.0.1), and changed the PPP connection from "In modem" to "In computer", which turned off the modem's internal PPPoE dialing. I then switched the router over to PPPoE on the Internet connection, plugged in my connection information, and let the router negotiate the PPPoE connection rather than the modem.
Now all is just rosy. I went through several iterations of turning off the modem, turning it back on, letting it negotiate the connection, turning on the router, letting it negotiate the DHCP connection with the modem, then losing the connection a few seconds later... I'm surprised I'm not a 'hair club for men' candidate by now. 
One thing I noticed with the new configuration, however, is that the router will only successfully act as a DNS server maybe 1 out of 3 connections (using firmware 1.52.9), so I've had to 'hard wire' all the DNS server addresses into all the client computers to get around this issue. I've read several threads that recommend this anyway in this forum, but it was nice to just have all the computers point to the router (but it's done now, so no big whoop).
Anyway, that just about covers it... if anybody else is using this router/modem combo, did you run into this issue, or was I just lucky? 
Also, I should add that the modem is running the latest firmware available on the web (can't remember the url offhand). The version it came with was several releases old (not surprising). |
|
d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
| Re: [General] BEFSX41 / Siemens 4100 DSL Modem problem and solut
You maybe could have saved yourself some hair if you had posted in one of the at&t forums. Hopefully someone would have directed you to one of these FAQ's:
»/faq/12670
»SBC DSL FAQ »How to setup the 5100b or 4100 with a router/hub
It sounds as if the modem wasn't set to "Always attempt to connect".
I personally don't use the 4100 modem to make the PPPoE connection because I have a more complicated arrangement involving another router and switch. What you have done by using PPPoE on the computer or if you use the bridged mode is cut yourself off from the modem's stats unless you un-cable and connect directly. It sometimes is nice or even critical to be able to check your DSL stats instantly. That is why I generally recommend using the using the modem's PPPoE client unless there are specific problems with that arrangement. Your problems should have been solvable with the modem settings.
I've been using the router as a DNS proxy with no problems. It seems to be 100% reliable as far as I can tell, but then I'm using the proven 1.45.7 firmware. |
|
graffixjones
Nuttier than Squirrel Turds
join:2006-03-28
Chico, CA
| Thanks for the heads-up on the FAQ entries.
Oh, and I tried every iteration of options on both the router and the modem (including 'always attempt to connect'), but hadn't figured out that the DHCP server on the modem always serves out the 192.168.1.64 address... I'll have to give that a shot, since it was kinda nice having the modem do the negotiation.
The only problem is that the FAQ doesn't address the router failing to see the modem on the WAN port, which is essentially what was happening. I could get the modem to connect to SBC, the router would then connect to the modem (I could reach the modem interface from my host computer), but two net hops later and it was suddenly unreachable.
After 16 hours, I was just happy to be back online again with my network.
I'll give those FAQ entries a shot and see what develops... now that I know how to get back online without a problem it probably won't be such a stressful situation.
I also tried the 1.45.7 firmware, but for some reason the NTP server wasn't working for me, and I like having timestamps on my log entries. I read that the 1.52.9 firmware wasn't too bad, so I updated to that and haven't had any problems to speak of (the original problem was occurring with both the 1.52.9 and the 1.45.7 firmware on the router). |
|
d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
| reply to graffixjones
Perhaps Comcast was the problem with the NTP server. I have never had any trouble with at&t's routing to the server.
I don't think I understand what you are saying here: "but two net hops later and it was suddenly unreachable." Does that mean you would see pings to the first two routers past your modem and then a tracert would die"?
Are you running a software firewall such as ZoneAlarm by chance? |
|
graffixjones
Nuttier than Squirrel Turds
join:2006-03-28
Chico, CA
| reply to graffixjones
Sorry, I guess my terminology was a bit off in my last post...
Basically, this is the sequence of events when letting the modem negotiate the connection.
1. Turn on modem
2. Modem negotiates connection and 'internet' light lights up signaling an active connection
3. Turn on router
4. Router negotiates a DHCP connection with the modem.
5. Fire up browser on my host computer.
6. Browser successfully connects to my home page
7. Point browser at 192.168.0.1 (modem interface)
8. Modem interface comes up
9. Point browser at a different website (such as slashdot)
10. Point browser at another website...
11. Nothing reachable from this point, including modem.
12. Lather, rinse, change options in router and modem, repeat...
So, by 'two net hops' I meant that I could connect to two external IP addresses, and then the router would stop communicating with the modem, and the internet would be unreachable. I could still connect to other computers on my network, but nothing over the WAN port.
Oh, and ZoneAlarm is a no go... I'm on a Mac.
Thanks again for your input. |
|
d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV | reply to graffixjones
That sounds strange. Your LAN subnet isn't either 192.168.0.xxx or 192.168.1.xxx is it? If you tried to use either of those, I would imagine that you would have strange results. |
|
graffixjones
Nuttier than Squirrel Turds
join:2006-03-28
Chico, CA
| reply to graffixjones
Actually, my network addresses are all 192.168.3.x
I agree, it's strange... I just tried doing what the FAQ suggests, but was unsuccessful with setting a static IP on the router.
I think my BEFSX41 is a V1, since it has three lights for each port, so I don't know if that makes a difference or not.
It appears to be working alright like it is now, though like you pointed out, I don't have direct access to my modem stats... but I figure if I have a problem I can always just connect it directly and diagnose that way.
Thanks again for the pointers. |
|
d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV | reply to graffixjones
There is another way to get to the stats and use your current PPPoE on router set up if you have a dependable switch and another old (or new) router kicking around. |
|
graffixjones
Nuttier than Squirrel Turds
join:2006-03-28
Chico, CA | reply to graffixjones
Thanks again d_l for your help.
I 'do' have another switch hooked up to my network, a Linksys EZXS55W 5-port.
So, if there's a way to hook everything up so that I can both use the router PPPoE and also access the modem I'd be golden. |
|
d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
1 edit | reply to graffixjones
What I've done is basically set up my SX41 and 4100 just like you have. The SX41 makes the PPPoE connection and the modem's PPP is set to be "PPP on the computer".
Then my EZXS55W is inserted between the SX41 and 4100. The PPPoE encapsulated packets pass right through the switch.
A second router (I originally used an old SR41, but now I use a WRT54GS) is in "parallel" (not really the best way to describe the topology set up, but it is close) to the SX41. This second router is set to a static IP on the same LAN subnet and the DHCP is disabled on it. A patch cable connects one LAN port on the SX41 to a LAN port on the WRT. If you have ever spent any time on this forum, you will recognize this as the classic way to add wireless capability to your wired router with a wireless router. It also results in the net addition of two more switch ports to your network.
The classic "add a WAP method" says don't use your WAN port on the wireless router, but for my set up, you will connect the WAN port to the switch and set the second router's WAN to internet connection type of DHCP. The 4100 will always issue the 192.168.1.64 IP to the WAN port of the second router.
Now here is the tricky part and I don't know if you can even do this with a Mac. The computer, SX41, and second router can't seem to consistently get its static routing through through the switch side of the SX41 and on to the second router and then out to the modem unless you set up a static route in the computer.
In Windows, this is done with the route add command. I use these two routes with the persistent switch set:
route -p add 192.168.0.0 mask 255.255.255.0 "2nd Router IP" metric 5
route -p add 192.168.1.0 mask 255.255.255.0 "2nd Router IP" metric 5
These routes will get your packets to the modem and to the WAN side of the second router (which really serves no pressing purpose).
The disadvantages of this method:
•It costs more with the second router and switch.
•It uses more power.
•Once in a blue moon (every 2-3 months) the switch will twitch and the router will drop the PPPoE connection and reboot (this may just be random reboots of the SX41).
The advantages:
•You can check the modem's stats without relying on the modem's pass along of de-encapsulated packets which may cause problems for a VPN connection.
•You can actually reboot the modem from its GUI with out losing your PPP connection. The connection is broken while the modem reboots, but you resume your link and IP once the reboot is finished.
•You can continuously pull stats from the modem AND continuously ping a site on the internet for diagnostic purposes. This can't be reliably done when the modem is making the PPPoE connection. Generating the stats output is a big load for its CPU and it sometimes get scrambled and unable to PPPoE encapsulate outgoing packets. If the PPPoE encapsulation is off loaded to the SX41, then there isn't a problem doing both.
Edit: It goes without saying that all these network devices and modem positively need some sort of UPS back up power. A power drop or fluctuation besides frying your equipment can wreak havoc on the stability of this set up. |
|
graffixjones
Nuttier than Squirrel Turds
join:2006-03-28
Chico, CA
1 edit | reply to graffixjones
Wow, thanks for that informative post.
Well, I've been playing around a bit more, and I think I came up with another solution... and I smacked myself upside the head once I discovered it.
The key (for me) was to click the little radio button next to 'Use Private IP' on the modem's connection configuration page for the LAN device... doh!
Before, the modem was passing the public IP to the router, and that appears to have been causing problems with communications between the two.
Of course, I just tried this about five minutes ago, so it's still up in the air as to whether or not it will work long term... the fact that I'm actually able to surf here to the site to answer this thread is a good sign. Now that I think about it, my problems started soon after upgrading the modem's firmware to the latest SBC firmware, so chances are that button got reset (it had worked fine for 24 hours prior to that).
And yes, Mac OSX can add routes to an interface, since it's pretty much a BSD derivative underneath, and I believe that XP also uses BSD networking, so they're essentially the same animal.
Thanks again for all your help. It's much appreciated.
David.
P.S. I also set my router up with the static private IP address on the modem, so I don't have to worry about DHCP negotiation between the two... that way if the modem goes down, I don't have to worry about the router locking up while the connection resets.
Thanks again. |
|
d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
1 edit | reply to graffixjones
So if the modem drops out, the lack of a DHCP server for the SX41 causes a type of lock up for the router while the modem reboots?
Thanks. I didn't know that and it may explain some some problems other have had with the 4100 and other routers.
Edit: Passing the private address would preclude the SX41 from handling DDNS updates, but if it is a stable arrangement for you and you don't need DDNS then use it. Otherwise that is another advantage to my set up. |
|
graffixjones
Nuttier than Squirrel Turds
join:2006-03-28
Chico, CA
1 edit | Man, this sucks. I typed like three replies so far and the reply box just locks up and won't send it. Are 'basic' members throttled or something? If it's more than a couple sentences it gets stuck. |
|
d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
| reply to graffixjones
The settings you have tried should work for anyone. I don't think it is due to your Mac, but that is possible.
Maybe if we try to go through a check list of settings. One thing jumps to mind on a switch from cable to PPPoE DSL would be the MTU setting in the router. You would want it set to manual 1492 because automatic doesn't cut it. |
|
graffixjones
Nuttier than Squirrel Turds
join:2006-03-28
Chico, CA
| reply to graffixjones
I think I discovered a bug, but I'll wait and see if it rears it's head again.
For some reason, I couldn't post anything longer than a couple of sentences there for a bit, which was a problem with my setup. As a quick test, I set everything back up like it was previously (with the router doing the negotiating), and I was able to post more than a couple sentences to the board... weird.
What I was trying to say to your original post was that in my experience, the router would lock up whenever the WAN port dropped. I could still see the inner network, but trying to connect to anything over the WAN port wouldn't work until the router went through a hard reset (i.e. unplugging it).
I don't use DDNS, so that's not really a problem. If I need access to anything, I can just put it up on my hosted website, or in my SBC Yahoo briefcase.
That was a weird anomaly though, not being able to post... I wonder what would be causing that?
One thing I discovered too, is that the newest Linksys firmware 1.52.9 does not accept 192.168.0.1 as a valid gateway address when trying to input it under the static IP configuration. However, it accepts it perfectly fine when in DHCP mode... another Linksys bug it appears. |
|
graffixjones
Nuttier than Squirrel Turds
join:2006-03-28
Chico, CA
| Okay, I got the 'bug' figured out.
My subnet mask was wrong... I was using 255.255.255.0, when it needed to be 255.255.0.0
The weird thing is the 1.45.7 accepted that subnet mask without a problem, and it functioned fine... man, the more I learn, the more confused I get.  |
|
d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
| reply to graffixjones
I think you lost me on that gateway address setting. Your router IP should be the gateway address if it is making the PPPoE connection and I think these Linksys routers may have problems static routing to more than a /24 subnet. That is just a guess based on their limitations of only 253 IPs (one /24 subnet) attached to the LAN and the fact that they can't handle more than one /24 net on the other end of each tunnel. |
|
graffixjones
Nuttier than Squirrel Turds
join:2006-03-28
Chico, CA
1 edit | Okay, I think we're both on different pages now, so I'll clear things up again.
Right now this is my configuration:
1. Modem set for PPPoE negotiation "Always try to Connect"
2. Modem passes 'private' IP (192.168.1.64) to router
3. Router set for Static IP on WAN (192.168.1.64/255.255.0.0)
4. Router set with gateway (to modem) 192.168.0.1
5. Router LAN address is 192.168.3.1
6. Client computers set with 192.168.3.x/255.255.255.0 addresses
7. Nameserver on client computers set to 192.168.3.1 (which is also the router setting).
8. Router MTU set to 1492.
My previous configuration was:
1. Modem set to 'PPP on Computer"
2. Router set to PPPoE with connection information on WAN
3. Router set to 192.168.3.1/255.255.255.0 LAN IP
4. Client computers set to 192.168.3.x/255.255.255.0 addresses
5. SBC Nameservers set in client computers with router set to 192.168.3.1.
I hope that clears the air a bit.
I only have five computers connected internally, and a print server, so I don't think I'll have to worry about maxing out the router connections. This is just my home network.
One other thing, is that I checked out my modem stats, and it appears that my Line Attenuation is 50dB, and my SN margin varies from 11.5dB to 14dB... are those 'bad' values?
I ran a new phone line directly from the jack the DSL modem is connected to out to the phone box on the pole in my yard, which didn't seem to help the noise at all (I figure the attenuation is the loop to/from the phone company).
Thanks again for all your help. |
|
graffixjones
Nuttier than Squirrel Turds
join:2006-03-28
Chico, CA
1 edit | Oh, I should add too that I'm still stuck at the 1984kbps 'ramp-up' rate on the modem (just connected on the 27th), though I hope that'll work itself out now that I'll have the modem up for a consistent amount of time. |
|
d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
| reply to graffixjones
OK! Got ya about those network settings.
Those modem stats aren't very good to possibly poor. If your modem has been off for a significant time period (a good portion of a day or more) your ramp, it might be delayed, ie., run longer than the normal 10 days. See this FAQ: »AT&T Southeast Forum FAQ »How do I check modem stats & event logs? What do the numbers mean?
Do you have a POTS splitter or a microfilter at the end of that home run? You really need that component there or else you will probably be making a bridged tap with the star topology of the phone lines running from your place to that pole.
Seeing as your DSL stats are going out of the Linksys realm, you could post a copy of your techreadout page with your user ID/email address edited out over in a new thread in the PacBell/NVBell forum and I can chart them something like this: »Paying for 6 MB, getting ~2.4 MB... and maybe tell you if your line will make 3008 and what problems you are seeing. I'm still developing the analysis/forecasting methodology so it would help me out. |
|
