Tuesday, December 16, 2008

Reliance WiMax IP issue -- a logical solution

I have been using Reliance WiMax for the past 10 months. There has always been issues with the speed (I've a 2Mbps line while I used to get only 256kbps). However, I should admit, at least to me the speed is very reasonable these days (mostly above 1Mbps).

The most common issue with wimax (I would refer reliance wimax as wimax hereon) is the difficulty in getting an IP. The common mode of connection is by DHCP (reliance charges around 2k per annum for static IP). Here is where the problem starts -- Windows fails to get an IP dynamically.

The most common solution that the users and the customer care people suggest is to 'keep the POE adaptor always on'. This is a ridiculous solution, as it wastes power. Even in this approach there is no guarantee that you will have your IP ready when you reach home -- the DHCP lease expires in few hours (earlier I believe it was 6 hours, these days it is 2 hours). So the problem actually repeats itself every 2 hours, however, things are little different when the lease expires -- so mostly this solution "might" work except for the power wastage. People do this.

The other solution provided by many are the famous "windows" solution. Just redo from the beginning. Switch off everything and start from the beginning. I hope they don't ask me to go to office and then come back. Well this is like trying to get lucky!

Ok so why is this post. I've been trying to understand the whole scenario from the beginning. Thankfully I did, I believe -- at least with my understanding I am able to get an IP always in less than a minute.

Let me explain the architecture behind reliance Wimax. There is an POE adaptor which is the wimax antenna. An ethernet cable runs from the POE adaptor to your comp. Your computer is configured for dynamic IP from the POE adaptor -- now this is where it gets interesting. The POE adaptor is also another networking node (it has its own firmware and boots up; infact they can upgrade firmware over the air). The POE adaptor also needs to get an IP "dynamically" from their servers. So the POE can successfully behave as a DHCP server (dhcp pkts router pbly) only after it receiving its own IP address . But this takes a while and hence the problem.

Why that being delayed is a problem? Now I'm going to blame Windows for this. The moment POE starts, the network link between the comp and the POE goes active, and Windows starts looking for a dynamic IP from the dhcp server which does NOT exist as of now. After a while Windows gives up and reports 'Limited or No connectivity'! Now what is the state of connection with respect to Windows is probably not known to windows too. (Try assigning any IP to this adaptor at this point and you would see that Windows would just hang for minutes there). I believe there is some glitch here, and Windows is not optimally handling this situation. Because of this, even when the POE gets its own IP and becomes capable of serving as DHCP server, there is no use! Windows does not manage to get an IP. People keep refreshing; run ipconfig -- and just shows "Limited or No connectivity". To add to the complexity, if the IP is not obtained within a short while, most times, the connectivity between the POE and the wimax towers gets broken for ever -- in which case, I could recover only by restarting POE and getting a fresh IP for POE.

So, we need to do two things to get an IP easily:
1. Know when the POE gets an IP and gateway assigned.
2. Once POE gets an IP, immediately make windows to try acquiring an IP dynamically.

Second is easy to do. Keep the connection disabled, and enable it only when the POE gets an IP. The first one is the difficult part. A simple approach I can suggest is, disable the connection, start the POE - wait for a minute or so, enable the connection. This is much more meaningful than restarting everything (I know one friend, who removes even the plugs connected to the POE adaptor --- apparently he was told by customer care).

A hint for techy guys: I dont use this technique to figure out if the POE has got an IP. It is quite apparent, that just like any other networking product (like a router, wireless router), the POE also listens on a local IP address of So if you statically assign (mask: you should be able to reach the POE adaptor "locally". Now go to a browser and type ''. Now if you can proceed from here on your own, you can know if the POE has an IP. The moment you see an IP, just disconnect your connection and re-enable the adaptor in dhcp mode -- you should get your IP in seconds. I don't think I can give more info on this.

I had written a perl script to do this for me, and I'm still using it. So I just run this script after boot up, and it takes care of getting me an IP while I have a face-wash after reaching home.

You can try something similar with this info. Have fun!


  1. Interesting. I can understand the POE adaptor using DHCP to get a dynamic IP address, but why use DHCP for the PC-POE connection if it is problematic? Does your PC also get a public IP address (I would think not)?

  2. Yes ofcourse, I get a public IP. So the IP cannot be assigned by the POE to solve IP address reuse/conflicts. An IP to the PC should be assigned by wimax servers, but POE takes care of routing the dhcp packets and acts as a router (for which it needs an IP of its own first). I forgot to mention in my post -- POE and the PC get IPs from totally different subnets and even have different gateways. I think the POE's ip is not an internet IP rather local to reliance wimax infrastructure and they might be having a separate subnet for these IP address and network management.

  3. guys... question off the topic.. any suggestion on a good antispyware to use ?! i tried StopZilla in a different PC and it was very effective, but my PC has a 64 bit Vista and stopzilla isn't available for it.. any suggestions would be great..

  4. I assume you are looking for a free version. Sorry I'm not aware of any. I don't have any AV solution in my personal PC :)

    Just curious, is it your personal PC? why are you running 64bit and on top of that, vista of all things ;)

  5. nope.. not a freeware, looking forward to buy one.. yenna panna inga richie street ilayey :-)

    i had ordered a personal PC and it came with the bundle of 64bit visa in it, i didn't have much of choice in that deal... inga i may not get a chance to setup a different OS.. adhaan as a timebeing solution i was looking for a good antispyware which is even purchasable..

  6. Oh ok. If you are willing to pay, you can try trend micro -- i heard that they have one vista 64bit.