| You just need to make sure that the DNS is configured properly, and then you can install an additional GWIA. First of all some prerequisites: You will need a public IP number per additional GWIA, or otherwise you will not be able to create the necessary MX, A, and PTR records. For this example we assume that your first public IP number is 137.65.55.211 and your organization can use a whole range of 16 public IP addresses, so you can use the next few numbers as well. You will also need an extra box on which you can add a secondary domain with MTA and the additional GWIA. This could be either an existing server or a new server, as long as this server does not have any other SMTP processes talking on port 25 and can connect to the Internet with one of your public IP numbers. And yes, you do need a secondary domain, as explained in Chapter 10. We prefer to have a secondary domain database on the server where the GWIA is running, because the GWIA can then have access to a copy of the domain on the local hard disk. After reading the preceding section, you should find it pretty easy to understand what you need to do. Let's take a closer look: First you need to determine what your existing DNS entries are. Let's take a look at www.dnsstuff.com and assume that your current DNS configuration looks as shown in Table 32.7. Table 32.7. The Existing DNS Entries as Defined for wwwidgets.comDOMAIN | TYPE | CLASS | TTL | ANSWER |
|---|
wwwidgets.com | MX | IN | 21600 | smtp.wwwidgets.com. [Preference = 50] | smtp.wwwidgets.com. | A | IN | 21600 | 137.65.55.211 | 137.65.55.211 | PTR | smtp. wwwidgets.com. | | [TTL 3600s] [A=137.65.55.211] |
We want to add a second GWIA. For more clarity in this book, we will use a distinct name; instead of something like smtp2.wwwidgets.com we will call this server mx2.wwwidgets.com. This server will use IP number 137.65.55.212 and this secondary GWIA will be a fallback GWIA only; so we will use the preference 75. That way an external SMTP server will first try to reach our primary GWIA smtp.wwwidgets.com. So the ISP needs to create a few new records, and an email to the ISP could read like this: Dear ISP, Can you please create a few additional DNS records for our domain? We need the following three entries: A record: mx2.wwwidgets.com -> 137.65.55.212 MX record for wwwidgets.com: mx2.wwwidgets.com with preference 75 PTR or reverse address lookup record: 137.65.55.212 -> mx2.wwwidgets.com. Please do not forget to add the PTR record as well and inform us when ready. Thanks! Regards from your patient customer. Tip Make sure you do finish this task some days before you want to create your secondary GWIA, and also be sure to check the results. Quite often the MX and A record will be no problem, but for many reasons the PTR records can be difficult for some ISPs. There will be no problems if these records have been created before your secondary GWIA is "on the air," because the preference value for this GWIA is higher and the outside world will first try to contact your primary GWIA.
While you're waiting for the ISP to finish the task of creating those DNS records, you can prepare the new or existing server. After installation and configuration of the basic server, you need to configure this server to use the public IP number, in this example 137.65.55.212, and you need to make sure that the hostname is the same as the A record, in this example mx2.wwwidgets.com. The next step is to create a secondary domain as described in Chapter 10, "Installing and Configuring the GroupWise Internet Agent," and Chapter 19, "Building Your GroupWise System Correctly." You need to install the MTA on this server and the GWIA as well, as described in these same chapters. During the installation of the GWIA you need to make particularly sure that the correct hostname mx2.wwwidgets.com is specified and not smtp.wwwidgets.com. All you need to do now is configure this new GWIA according to the recommendations from Chapter 10, and then you're ready to go. You can test the new GWIA by using telnet to connect to port 25 on mx2.wwwidgets.com, and you should see a cheerful OK coming back.
That's indeed all you need to do. As soon as your primary GWIA is somehow not available, for example due to maintenance, your secondary GWIA will accept SMTP sessions and will forward all incoming messages to your GroupWise system. Warning Although this is all very nice and true for your incoming mail, a secondary GWIA will not automatically start handling all outgoing mail as well. Your GroupWise system will still try to send all mail via the primary GWIA. Before GroupWise 7, the only solution was to make some manual changes to make sure that all mail was going to be routed via the secondary GWIA. Some new additions to GroupWise 7 will give you automatic failover and thus redundancy on the outgoing SMTP stream as well, as explained in the next section.
|
