Mac takes a long time to get internet connection
 

My ISP is not the greatest, and sometimes the connection gets lost.

After resetting the cable modem by power cycling it, the internet connection is available, but it takes a really long time for the Mac to recognize that internet access has returned.

For example:

1. online ok
2. lose internet connection
3. mac applications report no internet access
4. re-establish internet connection to cable modem
5. apps still report no internet access
6. this continues for a long time
7. eventually internet access returns to mac apps

I am tired of waiting for the Mac to find the internet access again- is there a way to speed up the process and force the Mac to do what it needs to do?

What is happening on the Mac that takes so long?



thanks in advance...

Can you explain how you know that the internet connection is available?

Can you also explain what measure you use to say that the Mac doesn't recognize that internet access has returned? Please be a lot more detailed than what you said above. For example, if there are error messages, please copy them letter for letter here, and tell us what the exact circumstances of the error message are.

Although these may seem like silly questions, in fact they are quite important in order to know what the problem is and how to fix it.

Trevor

You could start by checking your network configuration in System Preferences, Network, Show: Network Port Configurations. The list of ports shows the order in which the Mac will try them. If, for example, you're connecting over ethernet and you've got Airport and Modem checked off and higher in the list than Ethernet, then the Mac will wait for those two to fail to connect before going to Ethernet.

On the cable modem: there is an indicator light that shows connection is good and there is a good ip address.



Safari- can't find server for known domains.
Safari- says "you are not connected to internet- try Network Diagnostics?" (not exact words)
Network Diagnostics- go thru steps, still no internet connection
Eudora- cannot find mail server.

(I understand some of these errors are DNS related, but some are also internet access. Either way, it takes too much time to restore internet access.)

Of course, when internet access returns, everything works normally again.

There is only one port configuration, for built-in ethernet.

Does "Show: " have "Network Status" or "Network Port Configurations"?

P.S. also by checking Network preferences. The cable modem is connected directly to Mac (no router), Network shows the ip address is local (192...) when no internet access. When Network shows the remote ip address obtained from ISP, then internet access is restored again.

If "Network Status": only Built-In Ethernet

If "Network Port Configurations": only Built-In Ethernet is checked. All others are unchecked. Built-in Ethernet is at top of list.

When you've got an address that begins with 192, you're connected to your ISP, but not the web. You're basically waiting for their servers at that point.

I get a 192 address from the cable modem even if the internet is physically disconnected.

The Mac stays on 192 for a long time after the cable modem gets an ip address (shown by modem indicator light).

I tried a few experiments just now-- when I click on "Renew DHCP Lease", that seems to make the Mac recognize the new IP address from the cable modem.

Could "Renew DCHP Lease" manually be the solution to force the mac to get back online?

Why doesn't the Mac do it automatically (and faster)?

When it gets a 192 address, it's getting it from the ISP, since 192 isn't self-assigned. Renewing manually may force the ISP's machines to respond faster, but it's still a problem with the ISP, and not the Mac.

I appreciate your help, but I must disagree. Please see my post above.

My cable modem assigns 192 to my Mac, even if internet is physically disconnected.

Here is more info:

Looking closer, now I can see there are (at least) two different kinds of delays:


1. When first lose internet connection- Mac gets "stuck"- old, good IP address appears in Network, but it is dead because there is no internet connection.

2. When internet connection is restored to cable modem- Mac does not notice the good ip address is available- Mac sees cable modem and gets 192 address, but does not get new ip address from cable modem (even though the cable modem has acquired a good ip address from ISP).


#1 and #2 are definitely Mac-related problems, imho.

Some "modems" act as a router and some modems run a DHCP server. So the IP address could be coming from the DHCP server on the modem.

If your modem is acting as a router, then both are problems with the modem/router. In case #1, the modem loses the internet connection, but doesn't 'tell' the router, which doesn't kill the Mac's IP address right away. When the internet connection is restored, the router doesn't pick up on that right away either, so there's another delay. Either way, it's your cable modem that's causing a problem, and that may be related to why you're losing the connection in the first place.

I think it's time to call the cable company and get a new modem, or possibly a new drop from the street.

IPs beginning with 192 are non-routable IPs, so it can't be coming from the ISP, but rather he must have a modem containing a router assigning the IP. If the modem/router is using PPoE to login to the ISP, this may be an instance where it is taking a while for the ISP's system to complete the login process and assign a routable IP to the modem. It does sound like there may be problems with the modem or the physical line connection.

It is just possible you may be able to test this hypothesis (to some degree) using a web browser and trying to go to http://192.168.1.1, which is commonly the default IP address of a router than supports browser configuration. If you get a login screen, try first just saying "OK" to login and if that doesn't work, try "Admin" as the user name and no password. If you didn't configure and set a password, the chances are good it doesn't have one. If all of this succeeds, you should be able to determine the configuration of the modem as well as its current status and observe as it attempts to obtain an IP from the ISP. It is not uncommon for there to be a SLIGHT delay in this, but not a really long one.

Ultimately, though, I agree with cwtnospam that this is an issue your provider should clear up for you by checking the equipment.

Joe VanZandt

If that one doesn't work, try http://192.168.0.1, which is another common router address. You can check your ip address in network preferences and go to that address dot one: xxx.xxx.xxx.1

Thanks, but the internet service is a direct DHCP connection to the ISP, not PPoE.

As I said, the cable modem has a good ip address, but there is a long delay on the Mac as described in #1 and #2 in post above.

The cable modem ( Toshiba PCX2500 ) does not have a web interface.

How do you know the cable modem has a 'good' address? You can't assume that it's got one because it has connected with the cable company's equipment. If the Mac has an address that begins with 192, then it got it from the modem, so it can't be the Mac.

My guess is that it isn't the Mac, the modem, or your ISP, but the cable that runs from the street to your house, especially if your house is older than twenty years. That cable might be the original cable from thirty years ago, and weather and time does affect them. If it isn't the cable, it's probably the modem, but in either case you still need to call the cable company.

It has an indicator light that displays the connection status, and it indicates when the modem has acquired the ip address.

According to page 13 of the user's manual, there's nothing about the LEDs that tells you it has a valid ip address. It will tell you that it is 'registered', but that's a step or two before getting an address.

From Toshiba link:

This would only be possible if the modem is acting as a router. It is almost certainly responsible for your initial 192.168.x.x IP assignment. Now, how it gets assigned it's own IP--that may well be through DHCP from your ISP, but if that's the case, then it is taking some time for the modem to get the IP. It MUST have a routable IP assigned to it (and I realize you said that the cable modem has a good IP address; but if it is losing connection and you are cycling the power, it is going to have to wait for the DHCP server to re-assign an IP to the modem, even if it turn out to he be same IP) before you can do anything on the internet. I don't really see any way around one of two conclusions: the delay is natural and to be expected from your ISP, or else your equipment is faulty. If it is dropping your connection, then that you have faulty equipment somewhere along the chain is a very reasonable assumption. Not all routers are configurable via web interfaces, so that's no great surprise. (Just by the way, PPoE and DHCP aren't mutually exclusive. A PPoE connection will normally receive its IP from a DHCP server unless you have a static IP, for which you normally must pay extra, if you can get it at all. Most cable systems won't supply a static IP.)

In post 11, you indicate that when you choose to manually renew the DHCP lease, which then picks up the IP from the modem. You ask why it doesn't happen faster. Well, I don't know the answer to that, but if it turns out that this works in those cases where you lose the connection, that does seem like a fairly small penalty. If this post means what it sounds like, the modem seems to be getting an IP from the ISP quickly enough but the computer isn't getting it quickly from the router/modem. That -does- refocus the question slightly, although if your modem is dropping the signal, it still seems to indicate some problem with the hardware.

Joe VanZandt

The user manual states:

[when the "Cable" indicator light turns solid green]

"Cable Modem registered and ready to transfer data".

Yes, and some of that data would be an ip address from the DHCP server. If that doesn't happen, you can't get any further.

What's most likely happening is that the modem has registered and thinks it's got a strong enough signal to work, but when it sends for an address, the request or the response doesn't get through.

Believe me, I'm not just guessing here. It's happened to me before, and they did need to replace the cable from the street to the house. They also closed some signal leaks within the house. Call the cable company.

Yes, that is what I have been trying to say from the beginning.


There is also another kind of delay problem (similar to above in level of annoyance, but maybe unrelated) that happens after Mac has regained internet access, involving DNS, that is isolated to Apple Safari:

#3 Cable modem has ip address and Mac has picked it up, but Safari still cannot load webpages (timeout error "safari could not find server"). This is a DNS-related problem. But, it seems to be a problem with Safari and the Mac OS. If I use Eudora, it will "try harder" and find DNS. Then Safari will work OK on the next page. It seems to be a Safari or OS problem, because the webpages that can't find DNS still can't find DNS, even if Eudora and other webpages are OK. Note that when I say "webpage" I am talking about separate Safari browser windows, even if they are the same URL.

It's the same problem. If you have a weak signal, Safari may time out sooner than Eudora. That doesn't mean there's a problem with Safari. It just points again at a problem between the modem and the cable company. If you really don't want to call them, check for any coax cables that are plugged into wall sockets, but not a tv/cable modem. The resulting signal leak could be causing the problem.

I spoke with ISP today.

They confirmed that what I have been saying is mostly correct.

The cable modem indicator light accurately shows whether or not the cable modem is connected to the internet. It does not receive a DHCP ip address, however; the address is manually assigned by the ISP and does not change. If the light is solid, the modem is connected to the internet.

The cable modem assigns a DHCP ip address to the Mac, so in that regard it behaves like a router. The ISP told me that the mac should recognize the ip address immediately when the modem light goes solid, and not have the delays I have experienced.

The physical connection to the ISP is very good. It is not a weak signal. Throughput is 50% higher than the contracted bandwidth and there is no packet loss.

The momentary outages are suspected to be due to bad physical connector on cable modem, so I am investigating that.

The ISP confirmed that releasing and renewing the Mac's DHCP lease would be a way to force the Mac to quickly regain internet access, and also confirmed that the manual step should not be necessary- the Mac should quickly and automatically resume internet access when the cable modem indicator light goes solid.

The connection delays as described above in #1, #2 and #3 still appear to be Mac-related problems.

Me, too! More than once, with different ISP's. It is a pain, most definitely.

But that is different than what is happening here.

Chiming in late here, but I have a similar problem with my home network as well. I have 3 Macs on my home network. I have a dual 500 G4, a MDD G4 1.25Ghz, and a macbook pro. Now my macbook pro and my PCs (win xp sp2 and my linux box) all surf the net at a very fast rate. My MDD G4 takes forever to load pages and for it to connect. I don't get it.

I have safari, firefox and camino installed on it and all of them run sluggish. It has 1gig of RAM in it (my MDD). It also has a clean install of OS X 10.4 that is also very up to date.

I think that it is a mac problem, and that perhaps its firmware or driver related that causes these slow ethernet connections. My macbook pro runs on wireless and it runs faster than my MDD G4 which is wired directly to my router.

I haven't yet found a fix for it and it is very annoying since my G4 should be able to surf the net fast like all my other PCs. My dual 500 G4 is kind of sluggish in general but its older, so that doesn't bother me. It runs how I expect it to run. The MDD G4 on the other hand should run tiger and web browsers no problem.

Look at my post again. Safari browser windows that timeout will never load, even when they are refreshed after new Safari browser windows pointing to the exact same URI load successfully and all other internet access is working perfectly. (Problem #A)

Safari fails to do good DNS lookups after internet access is lost and then restored. Eudora fails to do good DNS lookups if internet access is lost (which is expected), but when internet access is restored, gets successful DNS lookups right away while Safari is still failing. (Problem #B)

Connected to the internet doesn't mean that the modem has an external IP address. You can be connected but not get to the web. I once had a situation where I could get email, which comes from the ISP's server, but not connect to the web. Nothing is ever as straight forward as you'd think it should be!

From your posts, specifically #9, we know this, and we also know that the Mac would not try to get another address. As long as it's able to talk to the router, it thinks it has internet access.


Did you lose your connection while they were checking? If you didn't, anything they saw isn't going to help much. That's the problem with intermittent glitches, and why it's probably going to be necessary for them to send somebody out there.

A definite possibility, but on which side, ethernet or coax?

As I said, as long as the Mac thinks it has internet access (it can talk to the router) it will not try to reconnect. If the modem reconnects to the internet after a delay, the Mac will think it always had a connection.

In Safari, emty the cache: command-option-E. This won't fix the basic problem, but it will make Safari behave more like Eudora.

cwtnospam- thanks again for your helpfulness!

But, with all due respect, I think you may be getting a little confused, or maybe you are just confusing me.

Much of the things that you say are contradicted by my observations, as well as by my ISP. I must again disagree with some of what you say.

If it is helpful I can respond to your comments one-by-one. But it really seems like you are trying to shoehorn my situation to match your experience, but the situation is not very similar at all.

Is anyone else following this thread? Perhaps it would be a good time to hear some fresh ideas or differing opinions about why things are happening as they are.

what are you settings for your ethernet card? Is it set to auto? Try setting it to 100mb full duplex mode and see if that helps.

Slow speed is a different problem from losing the connection. Try entering DNS settings in Network preferences. Sometimes there's a delay where the Mac waits for the router to check with the DNS server if you don't have an address for the Mac to use.

I have noticed this problem on some managed switches. For some reason macs take longer to resolve IPs over DHCP than say a PC sitting right next to it on the same network.

However, when I set my G4 MDD to 1000mb full duplex I got page would not load on all my web browers. The machine itself has gigabit ethernet standard, but my switch on my router is only 10/100. I was able to duplicate this exact problem the OP was having when I set my G4 to 1000mb Full Duplex. no website would load.

I have a Linksys router at home, WRT54GL running DD-WRT SP1 Final firmware.

I haven't been able to fully confirm this, but I believe that Macs don't actually acquire the DNS address, they just keep relying on the router to provide it. I know that if you just use DHCP, no DNS address will apear in the Network preference panel while it does show the router address. Since most routers are designed with PCs in mind, it probably isn't a good idea to rely on them to provide the DNS server for every request. That's why I suggest entering the DNS server address(es) manually.


Which ones? As I understand it:
1) The connection drops randomly for all applications, then returns randomly.
2) Safari caches the error page and pulls that up even after the connection returns for other applications.
3) This is unlikely to be a software problem, since the Mac has nothing to do with the modem remaining connected to the ISP. By the way, I think that manually entering the DNS server addresses on the Mac may help a bit here too because the Mac will rely a little less on the router, but it's not likely to solve the problem.
4) The modem's 'ready' light cannot tell if it's got an IP address from the ISP's DNS server. It can only tell if the modem is connected to the ISP's equipment.
5) Since the Mac connects to the router portion of the modem, it will always get a local IP address (192.168.xxx.xxx) so the Mac will think it's connected to the internet even when the modem has lost it's connection to the ISP.

cwtnospam,



Incorrect. I think you have this backwards. In any case, it is irrelevant here. In my situation, if I have a connection to my ISP, I have a connection to the internet and access to all internet services. That was both confirmed by my ISP, as well as my experience- again, as I have described repeatedly.




Incorrect. That does not describe Mac operation, nor does it match anything I have described above.



Huh? Sorry, but that is gibberish and nonsensical to me.



Not exactly. My internet connection goes down momentarily, on occasion. I manually restore the connection and internet connection is resumed almost immediately to cable modem. After this, it takes a long time for the Mac to get the internet connection. This problem is the subject of this thread.



No. The Safari cache is not involved.



No. It is a Mac-related problem. Again, see previous posts.



No. Again, see previous posts.



No. When the Mac has 192 ip address, and no internet connection, the Mac is very much aware that it has no internet connection, and correctly reports such. However, getting "stuck" on 192 address with no internet connection is one of the problems. The Mac should get an ip address with internet access automatically and quickly, but does not unless a long time has passed or manual intervention renews DCHP lease from the cable modem.



cwtnospam, Could I make a suggestion? Instead of changing the events to match your opinions, please accept the information I have given in detail to describe what is going on. Frequently, it seems you either misunderstand or ignore some of the things I have described in detail above.

I have tried to give only facts and not jump to any wrong conclusions. But, if you disagree with anything I have stated that might be a wrong conclusion, please detail your reason for your opinion.

That way, everyone can understand what you are saying and we can all stay on the same page trying to understand what is causing the problems I am seeing. OK?


Thank you again, cwtnospam, and thank you for your patience with me. :)

Thank you to everyone else reading and posting in this thread, also! I appreciate everyone's help here and hope that we can identify and solve each of the specific problems I have identified and described in this thread...

It was set to auto. I changed it yesterday as you suggested.

It has not changed anything as far as the problems that I am seeing. The same problems remain.

(Throughput is the same in speed tests, but in my imagination it seems that some webpages load faster- but I can't say for sure about that.)

sorry to ask this if it has already been answered, but have you tried a different router or something else network hardware wise over than your toshiba broadband modem?

Also, what type of config can you set up for this modem since it hands out IPs and such.

What happens if you assign it static information for the DNS and use DHCP for everything else?

No. Previously, had a router on the modem to share the internet connection, but the router started to fail, so it is gone.

I don't know if the modem is failing... very frustrating that network devices can partially fail- why is that?

I don't have another modem, and would like to try to be sure the modem is failing before seeking a replacement. (If so, I will look for some good recommendations!)


ISP => cable modem => Mac



It is not configurable.




I was concerned about DNS earlier when I first started getting these problems, and tried a static DNS entry. It slowed the DNS lookups slightly, the ISP DNS (blank in Network preferences) was faster, and had no effect on the other problems.

The problem is with the Mac getting internet connection, not DNS. If the Mac gets the remote ip address from the router, then the internet connection works perfectly (except Safari problem #A, which seem to be a Safari bug) and DNS is OK.

thx

I'm not trying to change events, but some of what you're saying doesn't match what a router does, and some doesn't match what a cable modem does.

For example, you say in post #10:
That indicates that you're connecting to a router, since self assigned addresses don't begin with 192. Those addresses are for private networks and routers perform NAT, or Network Address Translation, to allow communication between the internet and the private network.

And in post #11, you say:
That indicates your connected to a cable modem with no router, since you apparently get a new address that does not begin with 192, and you can browse the web. ——Is this correct? Do you get an address that doesn't begin with 192 on the Mac?

I've read more of the user manual for your modem, and I'm fairly sure at this point that it is not acting as a router.

If that's correct, then you're getting the 192 address (I know: post #10) from the cable company when you first connect until the DHCP server assigns a 'real' ip address. This is normal for a cable modem. Then for some reason, you lose that address temporarily and the cable company assigns another 192 address to you, but you don't get another 'real' address until you ask for one by click the Renew DHCP Lease button in Network Preferences.

At this point, assuming post #10 is incorrect, it seems likely that whatever glitch is causing the temporary loss in signal between the cable modem and the cable company is causing both the loss of the ip address and the lack of a new one being established.

If post #10 is correct, then there's something wrong with the cable modem itself. It shouldn't be providing any IP address, but instead relaying one from the cable company's servers. I'm leaning more and more towards thinking that this is the case, especially since you mentioned in your last post that your router started to fail. I'm thinking that maybe the router wasn't failing, but the cable modem was, and it was making the router look like the culprit.

well there are tons of problems with ISPs and modems. Your ISP could have done some updates which would require that your modem be updated with the newest firmware to make it more compatible. Your filter on your coax cable line could have gone bad and you can have loss of connection that way (happened to me last winter, cable guy had to come out and replace the filters), your modem could just be going bad.

What other computers do you have access to? Does the problem reproduce with them as well?

Do you have access to any kind of router? Is it in your budget to go buy one?

thanks, cwtnospam.

No. The 192 address the Mac gets comes from the cable modem. See previous posts.


No. The 192 comes from the cable modem. See previous posts.


Not exactly. The Mac eventually gets the 'real' address, after a long time. It should be available almost instantly, but takes several minutes, unless manually renewing the DHCP lease.


No. post #10 is CORRECT. With all due respect, this is a good example where you are misunderstanding the information here.


AFAIK, there is no flaw in the cable modem operation.

The problem seems to be Mac-related, imho, and the ISP confirmed that the problem is symptomatic of a Mac-related problem.

The Mac should seek a means of getting internet access when it is needed, AFAIK/IMHO.

The cable modem cannot affect or control the Mac ip address (unless the Mac requests it), AFAIK/IMHO.

As shown by manually renewing DHCP lease, the cable modem seems to respond correctly to the Mac.

The Mac should not be getting "stuck" on 192 or take a long time to resume internet access when the cable modem has a good internet connection, imho... see previous posts for more detail.


whew, finally we are discussing the actual problem which prompted this thread!



No. The router problem was not related to anything in this thread.

Here is a question for everyone:

What happens on your Mac when you lose your internet access? or your network/router connection?

Does your Mac resume internet access quickly when internet access is restored, or does it take a long time before it is back online?

I hope it doesn't confuse things, but I am trying to understand what should be expected.

This is tiring, but I'll try one last time.

Did a level 2 tech tell you so? The first person that answered the phone is just reading from a script. If they can't solve the problem, you can't take their word for it that it isn't their equipment.

Not true. When the Mac has an address it believes is valid, and 192.xxx.xxx.xxx is valid as far as the Mac is concerned, then it will not and should not request another one. The reason it changes later on is that a new one has been sent to it, not that it suddenly saw that address as bad and requested a new one.

Not true. The modem's job is to relay information from the ISP's equipment. If it is faulty, it can adversely affect any bit of information passed through it, including the Mac's ip address, as can the the cable in between.

True, but that doesn't mean that it responds correctly to all other signals, including those from the DHCP server, nor does it mean that it correctly sends every request to the DHCP server.

If you want to go on blaming the Mac, that's fine with me, but it won't get you anywhere. I've told you it's likely the cable modem or possibly the cable. JDV told you, both in post #18 and #23 that it's likely to be your cable modem or cable, and tlarkin has told you in post #44 that your modem could need an update, you could have a bad filter or your modem could be going bad.

I hope you get it fixed, but I give up at this point.

Thank you, cwtnospam, now it seems we are making some progress, but I am still having a lot of difficulty understanding some of the mechanisms here.

Yes. Of course I would not accept information blindly from an ISP rep unless I was convinced it was accurate. We discussed in detail the workings of the ISP's internet service, my observations and problems, and possible diagnosis. A cable modem problem was not ruled out completely, but could not be pinpointed to be the source of problems, either.

If the cable modem is the culprit, it is limited to only one very small specific problem, and thus I cannot say it is failing at all. I will add detail about this below.


OK, I understand that, but do not understand why the Mac will not seek to acquire internet access when it does not have it.

In my case, the Mac must have a remote ip address in order to have internet access. Can I configure the Mac to always look for this? I tempted to experiment with setting the ip address manually so it is always there, but this has two problems- 1.) if internet access is not there, it does not help anything, 2.) the address from ISP is not static and may be subject to change.



OK. But what happens in this scenario- an unconnected Mac is plugged into an ethernet network. The Mac has no ip address originally, and then gets one from the network device. Does the Mac see the physical connection and request an ip address, does the ethernet network device see the Mac and issue an ip address?

My guess is the Mac must request an ip address- but, I don't know for certain, thanks again for your patience helping me out here.

I am having trouble understanding why a network device would alter a computer's ip address without being requested to do so by the computer.


It appears that it is working correctly in this regard. What do you suggest to look for to determine if there is a problem?


It appears that it is working correctly in this regard. What do you suggest to look for to determine if there is a problem?


Here is the only problem I can isolate to the cable modem, and I am not sure it is a cable modem problem:

1. Lose internet connection.
2. Mac retains good ip address, but has no internet access.
3. Restore internet connection.
4. Power-cycling the modem. [Mac usually has lost ip address at this time, or during power-cycling.]
5. Modem assigns 192 address to Mac.
6. 192 gets stuck on Mac, instead of getting good ip address.
7. After a few minutes, Mac gets good ip address.

Workarounds:
- unplug and re-plug Mac ethernet cable. good ip address is assigned instantly.
- manually renew DCHP lease. good ip address is assigned instantly.


Note that this is Problem #2 that I listed. Problem #1, #A, #B are separate problems and also still remain unsolved and unexplained.


cwtnospam, you have helped me very much to understand that the delay in Problem #2 occurs in a certain type of situation, and it is only temporary (a few minutes).

But does the delay indicate a problem exists, or is it how things are supposed to work?

IMHO, the delay should not occur, but I do not know for certain, thus I started this thread to hope to understand and preferably to find a solution.

does the IP change, or is it the same IP over and over again it keeps getting assigned?

The good ip address stays the same.

The 192 address seems to be the same all the time (I haven't always looked closely).

it kind of sounds like your modem from what you described. Also, just so you know your ISP, no matter what level of tech (could be a level 50 wizard tech) will almost always blame your equipment first.

Maybe if I explain my setup, it will help you to understand yours.

I have a cable modem and two routers. The first router is a Lingo VOIP router. As a router, it is terrible, but it needs to be the first thing connected to the cable modem in order for my phone to work. This is important because of what happens on the rare occasions we lose our cable (both TV and computer, nobody knows why) for up to ten minutes.

When this happens, the Lingo router very often will not connect back to the ISP when cable returns. To re-establish access, I need to connect the computer directly to the modem, wait for it to get an address, and then switch the ethernet cables back to their normal setup. When I do this, the Mac first gets an address that begins with 192 from the cable modem (more precisely, from the cable company) that lasts for at most a couple of seconds before being replaced with a routable internet address. That's when I switch cables back and the Lingo router can connect.

If your cable company's setup is anything like mine, then you're getting that initial local address but not receiving the routable address until much later. It's likely that the DHCP server sent it to you, but you didn't receive it because of a bad cable or modem, and then at a later time, the cable company's system sees that you're still on the local address, so it sends it again. This process could repeat itself many times before an address finally gets through, resulting in considerable delays.

Note that the Mac is quite happy to go along using the 192 address forever, and will not request another address as long as it has this one. In fact, my Mac's address right now is: 192.168.0.100 because it is connected to a router which does Network Address Translation (NAT) so that my Mac can communicate with the internet.

As I see it, your biggest problem at this point is going to be convincing the cable company that something like this is going on and they need to send somebody out to fix it. As Tlarkin pointed out, they're inclined to blame your system first. They get paid to close tickets quickly, and blaming your computer is the fastest way to do that.

Could anyone please answer the question above for me?

It will help me understand what I should expect to see happen between the Mac and the cable modem and greatly help me to isolate the problem further.

Perhaps, but I what I observe does not match your suggestion that the cable company sends information to the modem in response to the status of the Mac.

1. If get delay after power-cycling modem, the delay seems to be the same amount of time (several minutes) consistently. That rules out a problem where you suggest the ip address has to be re-sent because it has not been received properly.

2. If Mac is unattended and internet connection has been lost, but internet connection to modem is restored, the Mac almost never gets back online unattended. (I will call this "Problem #4"). That suggests that even if ISP sees the Mac is only locally connected, the ISP does not do anything in response. That also rules out a problem where you suggest the ip address has to be re-sent because it has not been received properly. On the contrary, it appears like it is never sent, thus the Mac remains offfline.

IMHO there is no problem between the modem and ISP.

I agree there is some possible problem between the Mac and the modem.

But I am not convinced the modem has such a specific failure as to only have the problems I am seeing.

Perhaps this link may help: http://homepage.ntlworld.com/robin.d...hcp.html#lease

It is essentially a two-way process.

Joe VanZandt

Here is some additional info:

cwtnospam- as I said, the modem will give the Mac a 192 address, even if the internet is physically disconnected. So, in this case, the ISP is very definitely NOT sending the local ip address to my Mac.

However, you also mention getting 192 address from ISP before getting "good" ip address from ISP. I see the same thing as you describe when getting the good ip address. It is always preceded by the Mac completely losing ip address. ie.,"stuck" 192 => few minutes delay => no ip address => 192 => good ip address). I cannot determine if the 192 address at this point is from the ISP or modem.

Here is the revised sequence of events:

1. Lose internet connection.
2. Mac retains good ip address, but has no internet access.
3. Restore internet connection.
4. Power-cycling the modem. [Mac usually has lost ip address at this time, or during power-cycling.]
5. Modem assigns 192 address to Mac.
6. 192 gets stuck on Mac, instead of getting good ip address.
7. After a few minutes, Mac gets good ip address. Here is the more detailed sequence of getting a good ip address at this point in time:
7a. Mac loses ip address.
7b. Mac gets 192 address. [I cannot determine if this 192 is from modem or from ISP. It is same address as when internet is physically disconnected.]
7c. Mac gets good ip address.

7a-7c happen within a few seconds.

Let me repeat: 192.168.x.x addresses are assigned by your local router (modem) because it is a non-routable IP address...it won't go past a router. So it is NOT being assigned by your ISP. Your router (modem) is assigned an valid, routable IP by your ISP through DHCP (those often remain constant for long periods, but it isn't the same as PAYING for a static IP--you aren't guaranteed it won't change). The router uses Network Address Translation (NAT) to provide your machine (with its non-routable IP of 192.168.x.x) with access to the outside world via the IP address assigned to your modem. Everyone who uses a typical router has an 192.168.x.x IP, but this provides no conflict because the outside world cannot SEE that address directly. It is internal to the network created by your router. If you use a simpler modem with NO routing abilities, the IP you would see would be the actual IP assigned by the ISP to your modem. This is generally considered risky because that opens your machine up DIRECTLY to the outside world, with all the attendant perils.

Joe VanZandt

Thanks for confirming, that was my understanding also, and thus I have been questioning some of the conflicting information in this thread.

I suppose it's possible that my cable modem and yours both supply a local (192.xxx.xxx.xxx) address (I'll test this later, when I'm sure I won't need internet access for a while) until they receive a valid ip address from the ISP, but it really doesn't change anything. Either way, your scenario fits:

1. Lose internet connection -- the modem is faulty and doesn't register this fact.

2. Mac retains good address because the modem hasn't recognized that it lost the connection, so it continues to signal a good connection to the Mac.

3. internet connection restored -- modem light says good, but this isn't trustworthy. All it means is that it thinks that it's got a good connection to the central office, not to the DHCP server or the rest of the internet. Even if it does have those, it's problem might be on the ethernet side. I tend to doubt this because it's more likely to receive a surge on the cable side.

4. Power-cycling the modem. Mac lost ip address because the modem finally recognized that it didn't have a valid connection and told the Mac.

5. Modem assigns 192 address to Mac.

6. 192 gets stuck on Mac, instead of getting good ip address because the modem didn't get one from DHCP. Why? Bad modem, bad cable (either coax or ethernet), other signal leak in house or on the street.

7. After a few minutes, Mac gets good ip address. Here is the more detailed sequence of getting a good ip address at this point in time:
7a. Mac loses ip address. -- Modem recognizes signal loss, revokes Mac's ip address.
7b. Mac gets 192 address. [I cannot determine if this 192 is from modem or from ISP. It is same address as when internet is physically disconnected.] Either way, same problem: Modem did not get a valid ip to pass on to the Mac.
7c. Mac gets good ip address. After who knows how many attempts, the modem gets an address from the DHCP server and passes it on to the Mac.

Don't try to make too much sense of the problem. Remember that it's possible for one tiny part of the cable modem to be bad, or one tiny, sporadic short to exist in the cabling that could be causing errors all the time without dramatically affecting your service accept for when it occurs at just the right moment. You could be experiencing slightly slower speeds (ie, 1.4999 mbps instead of 1.5 mbps) because of the same problem, but when it affects your ip address, it's all or nothing so the problem seems much larger. Then you have to go through the whole cycle, which may not error correct as well as when transmitting normal data.

There is a lot of misinformation posted by a few people in this thread.

The description I have given above is accurate.

Thank you to individuals who identified correctly what was happening.

To recap:
1. internet connection is lost.
2. modem recognizes connection is lost.
3. mac loses internet connection.
4. mac connects to modem via local address.
5. mac fails to renew DHCP from provider, because local address is considered valid.
6. current workaround- manually renew DHCP via System Preferences:Network.


At this point, I would welcome some useful suggestions for solving the problem, rather than guesswork and speculation.

A useful solution involves Mac restoring valid internet connection without any user intervention, and doing so very quickly.


Thanks in advance.

bump


The above scenario occurs when the Mac is connected directly to the modem.

When there is a router in between the modem and the Mac, the problem is very similar.

The router must be restarted to re-establish a good connection.

This is inconvenient and time-consuming.

Is there a solution?



anyone?

When the Mac "self-assigns" an IP address, it does so because an active connection is found but polling for a DHCP address failed. The Mac continues to pole until a valid response occurs giving the Mac an IP, Mask and Router address.

If the modem is failing to renew the address to the Mac & the router, then I would suspect the modem itself. Does recycling the modem restore the IP address?

there are a couple things that can happen when you have full signal on a network but no IP. If its a managed network, they could be out of IP addresses, so your machine just self assigns.

If you are running WEP, you could have compatibility issues and I have seen macs take forever to connect to a WEP protected network.

Thank you for that info, it explains part of the behavior we have seen but did not fully understand.

We do not see any successful results from this activity, if it occurs. We cannot confirm that it occurs.

It seems that once the Mac settles on a 192 address, it does not proceed to obtain a better address. That is where things get stuck, without hands-on intervention.


Yes, recycling the modem restores the IP address. We are seeking a solution to avoid the inconvenience and the hands-on requirement of recycling the modem.

Not a managed network. No WEP, either.

This is just a simple cable internet connection.

Correction

This is just a simple cable internet connection with occasional connection failures which are annoyingly too frequent, and require hands-on intervention which is inconvenient and time-consuming. argh.

Unless you've got hardware problems with both your Mac and and your router, it's got to be your modem or your cables. As Las_Vegas points out, it's more likely your modem.

cwtnospam, thanks for your suggestions, but please read the thread before commenting. I know you are trying to be helpful, but as can be seen previously, you have been completely wrong on numerous times in this thread. I appreciate your helpfulness, but it is frustrating to explain again and again that your understanding of the problem(s) is not correct.

The specific problems and a workaround has been well established here. The workaround is annoying and frustrating, and we are seeking a better solution to the particular problem.


Thank you for your patience and understanding.

I am hopeful that someone with a fresh approach and more knowledge than you or I will help address these items... :)

LOL! I read the entire thread before posting, and I see nothing in it that doesn't lead to the conclusion that you either have a bad modem, or there is a problem with the coaxial cables in your house or between your house and the street. I told you last May that you needed to call the cable company and get a tech out to check your modem and wiring. You still need to call them, and you will not solve this problem until you do.

Sometimes with cable it can be a bad filter as well. Last winter I had a filter freeze and crack on me and that was the root of all my connection problems. Cable guy came out and replaced the filter and haven't really had any major issues since.

bump for another attempt to get this thread back on-topic.

the issue here is solely a Mac-related issue (possibly in combination with semi-brain-dead router and similarly handicapped cable modem)


still looking for a real solution

I'm coming in late here but you seem to have said above that when you have a router in play, you need to restart the router in order to fix things.
That would seem to indicate that the problem is with the router and or the cable modem (their interaction) since the router is either working or not working - it doesn't require a Mac to be connected in order for the router to work.
If, for example, the DHCP server in the router is not working correctly, it has nothing to do with the Mac.

Yes, that is all correct.

The problem is in the interaction.

After an intermittent internet outage, the Mac receives a local IP from the cable modem's internal router. (I'm not being too clear here, I apologize. Suffice to say, the cable modem generates a "dead-end" local IP address for itself and the machine it is connected to (computer or router), and the Mac gets stuck on this connection, even after the internet service is restored, the cable modem gets a "live" internet IP address from the ISP's network router.)

Even if the internet service is restored and the cable modem re-establishes its connection to ISP, the Mac does nothing, because it thinks it has a good IP address. Which, technically, it is, although it prevents any internet communications.

The solution to the problem is for the Mac to request another IP address. Manual intervention via System Preferences:Network will do this. Manual attempts to use internet services (mail, browsing) will also work, with varying success.

However, unattended operation (such as automatically checking for mail periodically) will not cause the Mac to request a new IP address, and that is where the problem seems to be, AFAIK.

That would not be a solution. It would be a work-around and a kludge.

The solution is to get the router (or more likely the modem) to properly maintain the connection. As tlarkin pointed out, that might require replacing a filter. It also might require replacing coaxial cable, or stopping signal leaks inside the house. These are all things that your cable guy can fix.

I don't care what anyone wants to call it, but that is the only solution that I am seeking (as was politely suggested to you previously).

Then perhaps the easiest solution would be to write a script that automates what you do manually. Have this script run every so often and all should be well.
It is quite likely that merely turing the Ethernet (or Airport) connection off and on again (on the Mac) will suffice. If that is the case, your script could just invoke 'ifconfig en0 down; ifconfig en0 up' - you could test this by issuing those commands in a Terminal window.
(or en1 for Airport)

If the Mac gets a 192 address, it's not a self assigned address, but one from a router. Self assigned addresses on Macs are always in the 169.254.xx.xx range.

good suggestion (if only I knew how to make scripts), thanks :)

thx for terminal cmds

but wouldn't that interrupt internet service?

i think what I would like is for the Mac to periodically request DHCP (or renewal) at a shorter interval than the lease normally provided by each of the router/cable modem/isp.

clicking on System Preferences:Network:Renew DHCP seems to work well:

#1 it does not seem to interrupt an existing "good" DHCP lease, and

#2 it does seem to activate a "good" DHCP lease to replace a "bad" local-only/no-internet-service lease, which is exactly what we want to happen.

I don't know if this is scriptable?

Some kind of setting or ability for the Mac to do this automatically is what I was looking for, from the beginning of this thread. Reluctantly, I can understand why it might not be default behavior, or even in accord with standard networking protocols. But, for this instance, it would be very desirable behavior. Is there a possible configuration to accomplish this, without resorting to scripting- some Mac-based DHCP auto-renewal setting, perhaps? (Even though i understand that is normally controlled by router.)

I don't know of any way to get this without scripting (or of course, finding some 3rd-party utility that does the scripting for you).

Here's a kludge that you could set up launchd to call periodically:

If you ping cnn.com, it will always fail, so it will always reset the connection. You'd want to ping a site that will respond if you have a connection, but I don't want to single one out. ;)

Is there a cmd for DHCP request?

Then could just cron the request periodically, which would be same as scripting "Renew DHCP" button.



The ping condition test helps avoid unwanted disconnect. good idea, cwtnospam.


The problem still remains with the lag time before resuming internet connectivity.



Is there another way to approach this, by identifying a failure somehow?

For example, the error page Safari generates when trying to load a page after there is no internet connection. I don't know if something is written to a logfile, or some internal message(s) might be observable without much overhead somehow?

or when Mail or Chat or whatever lose internet connectivity, where a continuous connection is used and expected...



I guess a completely opposite approach might be to force the Mac to retain the old good settings, even after loss of connectivity, to prevent getting stuck on the bad local ip address... yes, that would be even kludgier, but might even work better here...

(I think I tried manually setting the IP address to match the one issued by DHCP when there is a good connection... but that particular approach did not work, unfortunately. So a different variation is needed, if this direction is to succeed...)


It still seems strange to me that the Mac will not try harder to get an internet connection, when all the apps are trying to use one and the Mac is aware it is missing an internet connection...




???

OS X merely relies on the servers it has been configured to use (e.g. the DHCP server) to work properly. When the DHCP server assigns your Mac an IP address, OS X doesn't second-guess the DHCP server by saying - no I don't like that one, give me another. That would be like someone asking the Motor Vehicle registration board for a different licence number than the one they have been assigned.
So if the IP address assigned doesn't work to provide a working Internet connection, OS X just assumes that there is something wrong with the Internet connection.

yeah, i understand that is how it works, and that it makes sense...

but, I cannot help wanting the motor vehicle department to issue a new license number to a good working car, when the car with the old license gets a flat tire! :D

P.S. and without waiting in line at the motor vehicle department! ;)

:confused: I don't understand why you're so set against calling your cable provider.

long story, lots of reasons.

outages are only momentary, sporadic, intermittent and infrequent. the downtime would be difficult to diagnose, and even if is quite clear the cable provider is at fault, here the uptime is well above their contractual obligations.

as anyone knows who has had to fight their internet service provider or cable company to provide reasonable service quality even when problems are severe, it is a time-consuming, aggravating, frustrating process.

in recent months i have seen an outage once every couple of weeks or so. even when the problem arose several times a day at its peak, connectivity was always present after re-establishing the connection using the manual steps described above in the thread.

one must choose their battles, thus this is not one i choose to fight the cable provider. i have made several inquiries, receiving the expected denial by the provider of problems on their end.

lastly, and most importantly, it remains desirable to find a solution within my control that can be applied anytime anyone might be confronted with this situation, which i imagine is not uncommon.

imagine unplugging your internet connection for a moment, all your network devices react, you re-plug your internet connection, but your internet services are not automatically utilized by your network until after you manually intervene.

that may be the expected and proper behavior under the circumstances, or even under the definitions and standards and requirements of networking protocols and technology, but it is nevertheless annoying, aggravating and time-consuming each time.

So, it would be ideal to find a technical solution that one can implement to avoid the problem entirely, given the fact of life that no internet connection will ever have 100% uptime reliability.

Unix also depends on BIND and DNS a lot and if it is taking a long time to reverse look up the DNS it could cause a delay in the time it takes to get a valid connection.

Does this problem repeat with Windows? Since it is not as DNS dependent as Unix or Linux, that is if you have access to a windows box.

Well, you could check for signal leaks yourself. Coaxial cable plugged into the wall socket, but not connected to a TV or cable modem on the other end could cause a problem. Anywhere that the wire in the center is exposed or the braided shield is frayed can cause signal leak. If the exterior cable is old or in a spot that might allow for excessive wear, look for cracks or exposed wire. If you find physical problems, you could easily use that to get a technician sent out. Once they're there, it should be easy to get them to replace a cable or filter.

Try turning on the UNIX Name Service BIND (Berkeley Internet Name Domain) via root terminal. It's built into OSX (as OSX is UNIX based) but off by default (not sure about Leopard) for some odd reason, but it's the UNIX native DNS. Well it's actually a suite of UNIX based utilities including nslookup and dig but contains a very good DNS server that may fix your problem if it's DNS related.