Any insight on moving an Exchange server from a T1 down to a 384 SDSL?

[vi edit]

A year ago when I put in our T1, cost really wasn't an issue because the expense could be spread out over 25 different profit areas. We are possibly going to be dropping a significant number of those profit areas, and thus loose the ability to spread out the T1 cost.

I pay about $600 a month for the T1 and I can get a 384 SDSL line, which is the fastest I qualify at, for about $140 a month. This DSL line would be through the same ISP as our T1 and our DNS hosting, IP Addresses, and current domains would all stay under the ISP. The only change would be in the connection speed....on paper anyway.

We run an Exchange server off of the T1 line, as well as a website only accessed by employees. We really don't have *that* much bandwith being passed, and with the implementation of the Exchange server, all big attachments are filtered off to the server where it's qued and emailed out oblivious to the user as to how long it takes to mail out. Same really with inbound mail. It's not like trying to pull down or send out a 2 meg attachment using POP3

As for equipment, I've got a Cisco 1601 router, and a sonicwall pro doing the routing and firewalling jobs. The DSL provider would provide me with an Efficient router so I could either hang on to the Cisco & CSU/DSU card, or I could ebay them off and maybe pay for my first six months payments

Anywhoo, other than making sure that all IP addresses remained the same, and all DNS hosting was unchanged as well, is there any other logistical problems that I would run into?

I know that my uptime will not be as good as the T1, that's pretty much a given, but other than that, anything you can think of?

 

[JustinLerner]

In conversions there are almost always some kind of issues, but it appears to me that they will be minimal in your case, especially if you set up and test the new circuits before the cutover, if you can. Then when your ISP cuts over the new connection and with the right IP addresses range I suppose and cuts off the other circuit. I'm not sure what they do, but I'm sure they know how to do it.

I would guess they have some sort of cutover scheme, so ask them how it will happen what sort of disruption to your specific IP addresses, DNS services, internet routing may occur.

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If you have the right ISP, they may also offer the capability to multilink SDSL with the right SDSL routers (if bandwidth needs increase in the future.) Usually they need specific Coppermoutain DSLAMs and you need anything that works with it, like some Netopia SDSL router models with addon module capability.

 

[Santa]

Even though you are filtering off the email attachments you will still be completley downloading each attachment sent to you before you filter them off. Only thing inbound filters help is internal bandwidth and virus protection.

Your best bet is to do as you have done and find out how much you are utilizing your current bandwidth.. put some sort of monitoring software up so it can watch the line.

Then you should know if you will max out your DSL line when you convert or not. response time may also suffer a bit but apparently money is the issue here.

 

[FUBAR]

You probably won't keep the same IP addresses, but that shouldn't be too much of an issue.

You could possibly, if their T1 subscriber subnet is the same as their DSL subnet, but it probably isn't. Tricky routing aside, that fact would probably screw you.

However, your DNS shouldn't be much of an issue. If they proactively set the TTL down on your DNS entry, then you probably wouldn't see 5 minutes of inaccessibliliy due to the change. You may have other issues tho while you get your server to talk at that address. It's when you do name server maintenance when the delay really comes in. Changing or registering your registrar info takes FOREVER, once it's in there it only takes a few minutes many times for IP changes to be alive.

 

[vi edit]

<< Even though you are filtering off the email attachments you will still be completley downloading each attachment sent to you before you filter them off. Only thing inbound filters help is internal bandwidth and virus protection. >>



I guess I wasn't too clear on that. We used to use outlook express and SMTP/POP3 to send and receive emails. When you sent out a big attachment, there was a pretty good length of time that it took for outlook express to actually connect to the SMTP server, and push the attachment over to that server. You could see the status bar dragging along. Same thing with POP3 when receiving. When you try and pull down a 2 meg file over POP3, you get a nice, slow moving status bar as the file is downloaded.

Not the case with the exchange server and Outlook 2k. Once the user clicks "send", the file is zipped off, and for all intents and purposes to them it's gone. Same as incoming. No hooking up to a pop server and waiting for the bar to go. Once their mail pops up, it's there.

I also double checked with the ISP on the IP's. They said no problem on the IP reservations, they should still be good.

It looks like a pretty smooth transition. But then again, things always look smoother than they actually work out to be

 

[Daniel]

<<

<< Even though you are filtering off the email attachments you will still be completley downloading each attachment sent to you before you filter them off. Only thing inbound filters help is internal bandwidth and virus protection. >>



I guess I wasn't too clear on that. We used to use outlook express and SMTP/POP3 to send and receive emails. When you sent out a big attachment, there was a pretty good length of time that it took for outlook express to actually connect to the SMTP server, and push the attachment over to that server. You could see the status bar dragging along. Same thing with POP3 when receiving. When you try and pull down a 2 meg file over POP3, you get a nice, slow moving status bar as the file is downloaded.

Not the case with the exchange server and Outlook 2k. Once the user clicks "send", the file is zipped off, and for all intents and purposes to them it's gone. Same as incoming. No hooking up to a pop server and waiting for the bar to go. Once their mail pops up, it's there.
>>



I think his point about the downloading of the attachments was even though you are doing it through exchange and it is transparent to the user, it still has to go over the 384k line which will cut into your bandwidth.

 

[blstriker]

I recently changed my site over to 384/384 adsl and it runs fairly well. Then again, I upgraded from 768/128. Stability is pretty darn good and I haven't had any extended outages. I pay about $70 a month for my dsl.

 

[Garion]

I don't know the details, but there's a way you can limit the bandwidth on an interface. Not typically done, but you could "tune" your T1 down for a few days, to see what life would be like at 384K. Let the execs decide if they find the performance acceptable for the price difference.

Use some kind of SNMP monitor to see your current traffic stats. You'll likely seen an average utilization of ~100-150Kb/s and bursts into the 1.2Mb/s range, depending on how often you query for traffic. If you're running anywhere above 180Kb/s (about 50%), you're NOT going to make your users very happy with a DSL line.

Anything else available in your area, like cable? There's new voodoo magic ways of combining multiple broadband connections for faster access. If your DSL went down, so would your website and e-mail, but you could still at least browse.

From a techncal perspective, if your router is fully configured by your ISP and they are going to move your IP's, there's very little that could go wrong. One thing that I would ask would be for a temporary IP allocation for the DSL line, so that you can get it setup and "burned in" to make sure there's not errors on the line or having stability problems. When it's solid fo a week, go for it.

Last question - What's the SLA (guarantee) on the DSL line vs the T1? Is the difference in service reliability acceptable to those making the decision?

- G

 

[Santa]

You could try and configure the CSU/DSU to work with only 6 channels as apposed to 24. This should give you the 384 bandwidth you desire. I don't belieave you can do this on the router itself. You can set bandwidth and traffic shapping but those only work based on congestion not a active rate limiter.
I have always configured CSU/DSU for the maximum channels used but have never tried to use less channels without some sort of channelizing hardware.

If someone doesn't say it can't be done and you want to try this make sure its after hours.. overpriced bandwidth is better than no bandwidth

 

[Soybomb]

have you considered a fractional T1? I'd really have to trust the dsl provider to run a server off dsl.

 

[vi edit]

I checked on a fractional T1. It'd be the almost the same price as I am currently paying for the T1

I guess when I originally got the line hooked up, prices were very competative and I I got a full T1 at $599 + $150 install fee. Currently, it'd run me $750 a month for the same exact T1 if I was to sign up for a new one. Prices have really shot up. They are charging $499 for the fractional.

I'm lucky because I'm grandfathered in at $599 a month for as long as I keep my service running.

Decisions, decisions. :frown: