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Dual Broadband Configuration - Help Please!!

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TotallyVoIP

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I am setting up a test configuration for a prospective client, who works in Finance, so everything has to have some redundancy. I can cope with most of their needs, but I'm not sure I'm taking the right path with regards their broadband, so please pitch in with comments/advice:
They have 2 broadband lines, with 2 separate providers, one of the routers is a Draytek Vigor 2820 with GSM failover, the other router I'm not sure of the make, but it supports wan fail-over. The set up is right now:
Router 1 - set with static IP's and the PBX would be using IP "1C" (router 1 Fixed IP 3rd in the range), ADSL is set to Wan failover to Router 2 incase of failure.
Router 2 - Draytek 2820, again static IP's from ADSL provider, set to failover to GSM (dynamic IP - 1 only) in event of failure (typically to protect against cables being cut/local exchange issue).

This setup is how their network was designed for maximum robustness within the price they wanted to spend.

The 3CX system was only going to use 1 NIC, with the machine having 1 internal static IP.
STUN was going to be disabled and use the static IP. (this is the prefered method if I understand correctly?)

Router 1 would have open "VOIP" ports for the "1C" external address pointing to the internal static IP (just like you would with a single broadband connection). So far no issues.

Router 2 for both the ADSL and GSM would have open "VOIP" ports hopefully pointing to the internal static IP of the 3CX box.
However the 3CX box, if it suffers a Router 1 failure, will be sending outbound packets using the External static IP "1C" which if 9as they need to) are replied to will hit a "Dead" end.

Is the solution as simple as enabling STUN and not using a static external IP?
If the lines had been cut (they recently had builders/road works do just that) then the GSM backup would not offer a fixed IP in any event, unless a dynadns account was used. But I don't think 3CX could cope with 2 fixed IP's let alone 3!
Or could the issue be resolved with using Dynadns to resolve to the 3CX box and not use STUN or a ADSL assigned static IP and use DynaDNS permanently?

Has anyone configured something similar? The next question would be about load balancing/QoS, but 1 step at a time!

I'll have a internal configuration on Monday to start testing/playing, but would rather avoid silly mistakes and take any help before I start that is out there.

My recent BT Broadband experience will get posted, as it was a total mess, but finally resulted in an 11mb connection from an initially rated 5mb and after their 10 days of "settling in" a speed of only 60k - yes as slow as a modem! Anyway, another post...

Thanks in advance.
 
Hello Richard,
I think that there are two ways to deal with this:-

1. is by using bonded ADSL, so if one of the ADSL connections goes down the other will continue. Care needs to be taken because you might not know that one has gone down until it is too late! There are providers out there who cater for this. There is then one IP address to 3CX that stays constant. Once you start using STUN, you compromise reliability of calls. This might be OK for an individual external extension though. Again, I like to use the same company to provide the SIP trunks as provides for the ADSL.

2. To not rely on ADSL or Internet at all. Use a gateway - either GSM, ISDN or Analogue. The VoIP provider can divert calls to this number if the adsl fails. I have used GSM as that has "killed two birds with one stone". The other thing it does is to save costs on outbound calls to mobiles. The cost is then recovered for the customer. Outbound rules can have alterntive routes, but I prefer not to do this as when there is a busy, as 3CX will retry on the next defined route. Instead, I would switch on the alternative manually on the outbound rules, or show someone else how to do it.

I hope that helps. I am interested in your issues with Broadband. I tend not to use BT as I have heard too many tales of woe.
Richard Crabb
 
One more thing.

I know that Spitfire provides this bonded ADSL or SDSL, but I don't think that Voip Unlimited do. I have not checked.

Richard Crabb
 
We have set up a similar setup although in the USA but it is 2 ADSL lines.

I prefer a Linksys RV042 router as it has other useful features such as site to site vpn and client pc to site vpn.

It has 2 wan connections which can be configured as load balance, fail over or a DMZ. Cost is $200.

I have it set up that Wan 1 is for their internet traffic and Wan 2 is for their VOIP.

We also have another appliance that is part of our security appliance. One of the many features of this is also dual WAN and failover. This is a more expensive version as it has about 15 different security and gateway features built into it (such as Firewall, intrusion prevention, attack protocol, anti virus, anti spam, anti phishing, web filter, vpn, dual wan, multiple internal networks etc. etc.).

PM me if you need any more help.
 
Hi,
The RV042 is a good router, but I do know that it will not at present work with Voip Unlimited. There is an issue now whereby when a SIP packet is sent for an incoming call (from Voip Unlimited to the customer), then that packet will be dropped. The reason is that many routers will not forward fragmented UDP SIP packets as is required for incoming calls from the Voip Unlimited network. There are some other routers that are also affected. I will do a post on this shortly. I do know that Cisco is looking into this issue. Draytek is also affected if the firmware is 3.3.4 or later.

Richard Crabb
 
RichardCrabb1 said:
Draytek is also affected if the firmware is 3.3.4 or later.

with the draytek 3.3.4.1 firmware you must UNTICK the fragmented packets.
On the Firewall --> general setting tab
UNTICK "Accept large incoming fragmented UDP or ICMP packets ( for some games, ex. CS )"

then the router works fine with Voip Unlimited, yes I know it seems the reverse, but apparently the draytek tick box is reveresed! We use this config with Voip unlimited just fine.

We use the draytek 2820 Vn (2 of them) and are testing the 2820 Vsn, which is upposed to have a built in FXO port. If the FXO port is not really there (only got it today, so not played yet) then it will go back!
 
Hi i was in the same situation with you. With 6 months ago i receive a contract to implement network redundancy ( phone too) for a software company. After some trials and couple PoCs ( proof of concept) presented to the client and after some field tests the best solution was BGP. In this configuration for the PBX it's not important what line it's used because the PBX use the same IP. I definitely recommend this solution.

George
 
RichardCrabb1 said:
1. is by using bonded ADSL, so if one of the ADSL connections goes down the other will continue. Care needs to be taken because you might not know that one has gone down until it is too late! There are providers out there who cater for this. There is then one IP address to 3CX that stays constant. Once you start using STUN, you compromise reliability of calls. This might be OK for an individual external extension though. Again, I like to use the same company to provide the SIP trunks as provides for the ADSL.

Ok, this would work if it was a need to have just 2 broadband lines, but would fail when the GSM cuts in, as this would be a different IP address.
Also the 2 broadband accounts are with different providers, as the client is paraoid aout a supplier network failure, so wants two different vendors, which he has.
The configuration of 2 routers, 2 suppliers and the GSM already exists, and has been working for network traffic for 18months or more.
My issue is how to have the VOIP link to 3CX maintain connectivity during the 3 possible failover configurations.
So far I think that a Fixed IP is unlikely to work, leaving
1. STUN
2. External IP resolution service like DynsDNS or No-IP
3. ... someone please enlighten me!

So out of those solutions (STUN or Web based Dynamic DNS resolving service) which is likely to be more reliable, anyone tried option 2 who can offer any advice/tips?
 
TotallyVoIP said:
They have 2 broadband lines, with 2 separate providers, one of the routers is a Draytek Vigor 2820 with GSM failover, the other router I'm not sure of the make, but it supports wan fail-over. The set up is right now:
Router 1 - set with static IP's and the PBX would be using IP "1C" (router 1 Fixed IP 3rd in the range), ADSL is set to Wan failover to Router 2 incase of failure.
Router 2 - Draytek 2820, again static IP's from ADSL provider, set to failover to GSM (dynamic IP - 1 only) in event of failure (typically to protect against cables being cut/local exchange issue).
Just to clarify the configuration, this was originally planned/installed 18months ago for network traffic (remote access, VPN, email etc), VOIP was not even on their horizon).

The system works as it is for that purpose, but for VOIP using fixed IP (the most reliable configuration I'm told), it would then be tied to a single ADSL connection (assuming that the GSM is merely last resort failover), and the moment that the line failed the phone system would lose it's IP and would not route via the failover ... unless I'm missing something, and assuming a bonded connection was not in place (due to client requirement of separate providers for teh 2 ADSL).
 
Here is another thought..

One idea might be to use Windows ability to configure static routes. This means that you would have two adsl routers, each with separate ISPs. Also, each one will connect to a given SIP provider. Static routing in windows means that you can define the IP subnets that would route via each router. Each router can then be configured with the appropriate static port forwarding. Unfortunately this is still of limited use.

Obviously IP routing will not take care of the alternate call routing. Also, 3CX does not have the ability to route calls to an alternative route when a SIP provider cannot be reached. It will however, reroute the call if busy or unavailable - not much use in this scenario. If 3CX could detect the failure of SIP trunks, and then re-route that would overcome this problem.

We are therefore back to BGP routing as the only true working solution. It needs a specialist who can properly configure the BGP routing - taking care of hardware redundancy as well. There is not simple solution to this!

Richard Crabb
 
To setup a BGP connection it's not very complicated what is rely complicated is to take the accept from the client to spent some money for equipments, to have an agreement with both ISPs ( more money) and the last is to have/buy a /24 ip class( again more money).
The BGP solution is the best fully automatically backup solution for VOIP and VPN ( point-to-point).

George
 
No. BGP is not very complicated - but must be done properly. Then to be useful you most likely need two routers rather than one. Also, you will need your own AS - autonomous system for BGP routing purposes.

I believe to back up telephony, some kind of intelligent failover to a gateway would be useful and cost effective. On 3CX, although you can configure alternate routes - these kick in on a busy signal, not just unavailable or loss of registration. To be useful 3CX needs to change routing when for example the primary SIP routes do not register, and or calls fail for reasons other than busy.

Richard Crabb
 
I have a question and then i have a left field thought for you

The question i have (and excuse my ignorance but i left the uk in 98 so dont know the current technolgy) is if it is so important to the customer to have internet access and there appears to be a problem in a dsl staying up, then why dont they go to a managed service such as a T1 (or is it too expensive there) than all this expense? Or why not put the pbx in the cloud and then it isnt an issue.

Now the left field thought:

The problem is that if you are registered through ISPA on an ip address with a provider and then it goes down, until you reregister then the provider does not know. You have lost the call in progress and nothing you can do about that as it was tied to an ip via registration.

So you need to know when an ISP goes down and then reregister. So if you had a small program or windows script file that ran all the time and pinged somewhere and got an ip back then you can compare ip's and if it is down then restart the 3cx service which will reregister with the providers (Takes less than 30 seconds).

That is cheap and easy and would work with GSM too. In theory you can still have a "static" ip as far as 3cx was concerned but i would stick to stun as you really need this in the GSM case.

Would that work as a cheap but reliable solution for them?
 
then why dont they go to a managed service such as a T1 (or is it too expensive there)
correct, cost. But the ADSL is pretty reliable (one failover in the last 18months), the issue is they want low cost solutions using the setup they have (or a variation on it).

Or why not put the pbx in the cloud and then it isnt an issue
Had not thought of that, but I think the client wants to host the PBX and you would still have issues of the phones routing to the cloud.

So you need to know when an ISP goes down and then reregister
I get your drift, but the Static IP would change, and the script you need to write directly to 3CX new IP and then restart the services. Not sure how simple or safe that would be.

An Alternative thought, was to have 2 3CX PBX's, with one on Each of the 1 on a fixed IP being the master and the second being the slave running on STUN, so when the master ADSL fails, the system somehow routes via the 2nd 3CX using STUN?

The other alternative is the Service Provider has an automatic re-route on trunk failing to connect, but that might only be good for Mobile Phone alternatives (as there would be no way to check the other ADSL etc).

So STUN looks like the easy solution, but how much does this reduce the preformance of the calls?
 
stun doesnt reduce call performance to a noticeable level. only 3cx is using stun not the phones.

stun is mainly used when registration occurs if i remember correctly (though 3cx can confirm this) and not for each call placed or received.

As for my suggestion a simple windows script or small application could be written for you (we are happy to look at it for you) that would reregister the voip providers.

rerouting would also help you
 
Hi
You might find this useful, and it is used and supported by Spitfire

http://www.virtualaccess.com/index.php/products/gw7000-dual-adsl/
 
Ok, here is my issue, sounds similar to the above.
I have a server with main line out to ADSL router, I also want a vodafone stick (plugged into usb configured to dial on demand) to work when the adsl line goes down for any reason., Would love a setting in 3CX that u could enter a 'alt external ip'
Now there’s a good chance I just haven’t explained myself well here so I think I’ll add a picture because they do explain things better than me.

backup.png


As you can see here, if the ADSL fails, ISDN, Backup ADSL and the 3G modem (that I want to get working) comes into action.
Please let me know if I have missed something and there is already that function available and if possible how to configure it.

Thanks in advance,

Darryn
 
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