ADSL 2+ Router with 3G Failover

Forums › LAN (ethernet/Wifi/routers/Bluetooth) › ADSL 2+ Router with 3G Failover - needs fixed IP??

tagoso

30 posts

Geek

Topic # 60707 30-Apr-2010 15:23

Hi team,

Firstly I apologise if this has been mentioned in the forums before - I looked but couldn't find anything.

We have a Vigor router at work - with a USB port which can take a 3G Vodem/Data card type connection in case the broadband fails. I understand that when the 3G kicks into life, we will be ok browsing the internet - but I really want it to receive emails from our ISP into the Exchange Server.
But the ISP needs a fixed IP to push the emails to.

What's the best way to handle this?

1. Have an offsite server pickup the emails and forward them to the 3G connection once we've established what the IP address is? (Requires manual configuration - no 100% auto failover)
2. Or is there someway to fix the IP on a 3G connection? I've heard that Telecom charge about $250 per month for the privilege and Vodafone have quoted $3-4K....although I'm not sure if that's just setup or if its an annual charge etc.
3. Even if I do manage to get a fixed IP address for the 3G, will the ISP (Orcon) be able to automatically swap to a different IP - or will that need to be manually configured when it happens?

We expect to use it 3-4 times a year - but emails are pretty important to us so we are willing to spend some money - was just trying to see what options are out there without paying silly money.

Any feedback welcome!

Thanks.

webwat

1984 posts

Uber Geek
+1 received by user: 133

Trusted

Reply # 325668 1-May-2010 22:17

I think there is an option to setup a secondary IP address for SMTP servers but I believe its part of the MX record on your domain name, although MS might not have implemented it on any particular version you decide to run. I am not really sure, but I think there is some function for a secondary MX. It might be better to setup a whole secondary mail server off site, which would give you an extra layer of redundancy if your local "Exchange" mail server blows up a power supply or hard drive. You could collect mail directly from it or setup a local "Fetch" server to act as a mail proxy that collects mail from the remote server.

I am wondering why Orcoon have to send emails to you since you host your own server and should be able to get them direct from any SMTP server. Do you mean that Orcon host your domain name? This means that any SMTP server that looks up your domain would find your IP address there as the MX for that domain, and send emails to whatever is connected on that IP address (which I presume is also hosted by Orcon). Perhaps you could ask Orcon if they can failover your main IP to a VPN that tunnels through your 3G card.

Qualified in business, certified in fibre, stuck in copper, have to keep going ^_^

LennonNZ

2353 posts

Uber Geek
+1 received by user: 373

Trusted

Reply # 325674 1-May-2010 22:37

Why don't you do it the other away around.. Telehouse your exchange server someplace and then the clients can connect from anywhere and you don't need a Static IP Address.

PenultimateHop

637 posts

Ultimate Geek
+1 received by user: 2

Trusted

Reply # 325709 2-May-2010 07:38

LennonNZ: Why don't you do it the other away around.. Telehouse your exchange server someplace and then the clients can connect from anywhere and you don't need a Static IP Address.

The catch to this is that intra-office email will then have to traverse your Internet connection, which means performance will be lower and it may use data caps. Of course if your end-users are mostly remote workers and not in the office then this may not be an issue.

Assuming you are receiving mails straight to your Exchange server from the Internet (e.g. publicly exposed MX records) then a solution to the problem might be to define two MX records for your domain-name, one which is your primary (lowest number = highest priority) which is via your broadband connection. The second could use a dynamic DNS name with a higher number (lower priority); and this dynamic DNS entry could be updated when the 3G service kicks in - either automatically if the router supports it (or via another tool); or manually if required. For security's sake and to avoid email disappearing, when the 3G service is not in use you should change the dynamic DNS entry be your broadband IP. This should work fairly effectively and reasonably automatically.

If you are using mailbagging and something like ETRN then the dynamic DNS approach would still work relatively well. If you're using mailbagging and POP to collect the mail then you don't need a fixed IP address at all.

I would suggest the use of direct-to-MX delivery though.

As a side note, if you are using your Exchange server for outgoing mail to the Internet, regardless of your fixed-IP not, for best practice you should relay your outgoing mail from Exchange to your ISP's mailserver to ensure your mail is not erroneously tagged or marked as spam because it does not come from a reputed mailserver. This may be a problem when on the 3G service, however...

richms

21235 posts

Uber Geek
+1 received by user: 4271

Trusted

Subscriber

Reply # 325808 2-May-2010 16:28

PenultimateHop:
As a side note, if you are using your Exchange server for outgoing mail to the Internet, regardless of your fixed-IP not, for best practice you should relay your outgoing mail from Exchange to your ISP's mailserver to ensure your mail is not erroneously tagged or marked as spam because it does not come from a reputed mailserver. This may be a problem when on the 3G service, however...

No you shouldnt, as you would have to put SPF records for the ISPs server to get thru lots of spam filters, and that opens your domain name as being used as a sender for all the compromised PCs on the same ISP.

Best to relay via your webhosting etc provider IMO, and that can be your secondary MX for when the DSL is down. They should be able to sort out relaying to a dynamic DNS entry for you as well.

Richard rich.ms

PenultimateHop

637 posts

Ultimate Geek
+1 received by user: 2

Trusted

Reply # 325816 2-May-2010 16:52

richms:
PenultimateHop:
As a side note, if you are using your Exchange server for outgoing mail to the Internet, regardless of your fixed-IP not, for best practice you should relay your outgoing mail from Exchange to your ISP's mailserver to ensure your mail is not erroneously tagged or marked as spam because it does not come from a reputed mailserver. This may be a problem when on the 3G service, however...
No you shouldnt, as you would have to put SPF records for the ISPs server to get thru lots of spam filters, and that opens your domain name as being used as a sender for all the compromised PCs on the same ISP.

That is true and is a valid concern, however I stick with my original advice. The risk of what you describe is much lower than the risk of being tagged as spam/outright bounced because you are coming from broadband IP space (dynamic or static), or suffering reputation issues when trying to send email to large mail companies like Yahoo! (Xtra) and Hotmail - as has often been complained about on Geekzone.

richms: Best to relay via your webhosting etc provider IMO, and that can be your secondary MX for when the DSL is down. They should be able to sort out relaying to a dynamic DNS entry for you as well.

Relaying via your webhosting provider is an alternate option that should achieve the same result as relaying through your ISP; although the risk you describe above still exists there too - and it assumes that your mail server can use e.g. SMTP Authentication for outgoing mail relays which may or may not be possible.