2 separate T1 lines/routers into 1 LAN ?

March 18, 2010 at 06:18:27
Specs: Windows XP
we have an old T1 and we are getting a new
T1.
both are separate lines with different IP
address and different routers (cisco 3640 and
1841).

is there a way to bring both T1 lines into the
LAN?

the reason - we have an internal FTP server
which we cant have down - we would like to
avoid dropped FTP transactions while the new
T1 IP propagates by created a 2nd A record to
point ftp.domain.com to the new IP address as
well as the old IP address.

or if you have a better solution to avoid down
time please share, thank you


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#1
March 18, 2010 at 06:33:00
If it's an internal FTP server, DNS has nothing to do with it. Use the internal IP address. It doesn't have to leave the LAN.

ftp 192.168.1.21 or whatever it is. That's how I connect to my internal servers.

How do you know when a politician is lying? His mouth is moving.


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#2
March 18, 2010 at 08:08:11
Guapo's right about internal access.

With regard to external access. If you have access through a website, which is to say, click on a link in your web browser, then that will have to be changed with the website itself since it links to the IP.

If you're talking about typical ftp access from a command line, which requires knowing the IP address then you must already have a plan to alert users to the IP change. Just tell them, using the same method, about the changeover, the Date, expected duration of downtime, and the downtime period, while telling them about the IP.

As for web access, put a big notice on the access page about the changeover listing the same info as above.


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#3
March 18, 2010 at 08:39:03
hi thanks for responding!

no my question is of different nature.

we have an internal FTP server where clients access to
submit files to and from. they all have various access manners
but they all use ftp.comapny.com.
ftp.company.com resolves to our T1's external IP address.
once we switch to a new T1 with a new IP the DNS name
propagation will change ftp.company.com to the new extremal
IP which will cause downtime.

i was hoping by having both IP's (new and old) point to
ftp.company.com once the A record has been changed to the
new, even old requests will find their way into my FTP server.

hence my question - can i plug two routers with two different
external IP's into my network ?


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Related Solutions

#4
March 18, 2010 at 08:50:29
hence my question - can i plug two routers with two different external IP's into my network ?

Yes you can. How you're going to accomplish this of course is going to depend on how you're setup and what equipment you're using.

You haven't mentioned how you have them connected internally but I would suspect it's something like:

T1 >> Router >> Firewall Appliance >> Switch >> LAN

Of course I'm just guessing so please clarify how you're setup and we'll go on from there.


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#5
March 18, 2010 at 09:19:26
hi, yes its similar-

T1 >> Router / Firewall (same appliance) >> Switch >> LAN

my old T1 uses a cisco 3640 with a wic-1dsu-t1
my new T1 (its a two meg) uses a cisco 1841 with vwic-2mft-t1-
d1 card (2 T1 lines merge into one)


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#6
March 18, 2010 at 09:46:00
If the new router is also a combination router/firewall then hook it into the same switch. Once the new T1 is up and running, you can then make the necessary host record changes and once everything is working properly, disconnect the original T1 service and router.

If the new router isn't a combo unit, I highly recommend putting a firewall between it and your LAN.


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#7
March 18, 2010 at 09:52:54
so you confirm that i can just plug a 2nd router with its own IP
and all to the same switch the 1st router is connecting to?
which dns will the domain controller be pointing to?

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#8
March 18, 2010 at 12:16:40
so you confirm that i can just plug a 2nd router with its own IPand all to the same switch the 1st router is connecting to?

Yes, I can confirm that. We have two external connections, from completely different providers, here where I work and they both connect to the same switch.

Keep in mind that there is still some setup required to make it all work. You won't just be able to plug the new T1 in to your switch and expect it to work. There are changes you will have to make. If you're not sure which changes you need to hire a professional consultant to help you do the changeover.

which dns will the domain controller be pointing to?

That depends on which one it's using now. If you have your DNS server forwarded to your ISP's DNS server then you will need to change that to the DNS server(s) of your new provider once the new T1 is connected and working.

Again, I can't stress enough that you need to leave the old, working, T1 connected until you're 100% sure the new one is working.


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#9
March 18, 2010 at 12:22:48
super.

ok but what changes? changes on the routing side?
give me a general term for whats involved? IGRP? load balancer?

not looking for scripts and procedure pdf's, just a general idea of
the theory behind making this work :)


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#10
March 18, 2010 at 13:08:28
Look, I'm very sorry but you're asking for too much.

You're obviously not qualified to do this yourself and I highly recommend you hire a professional.

You can hire me. I charge $250.00 per hour and you'll also have to pay my expenses (travel/meals/hotels etc) since this would require an onsite visit.


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#11
March 18, 2010 at 13:22:32
thanks i will consider it. your advice was much appreciated!

i am still looking for a an answer so i will keep this open for now.


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#12
March 18, 2010 at 15:53:02
Your original question should not have described your FTP server as internal. My servers are internal. They can't be accessed from outside the LAN.

How do you know when a politician is lying? His mouth is moving.


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#13
March 22, 2010 at 09:22:58
true dat :)

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