Dear Doctor,
A neighboring company with a high-speed Internet connection similar to ours, but from a different provider, has proposed that we pool our resources so that one company's connection can support the other company should it lose Internet access. A Cat-5 cable already interconnects our two data centers. I've found a number of firewalls that support dual-WAN configuration, so we bought a pair and paid for a fiber optic cable between our buildings. Alas, I can't figure out how to... Read the rest of entry >>
Posted @ 09/01/2008 4:06 PM By Mel Beckman
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Dear Doctor,
We've recently seen a sudden increase in reports of lost email — email our users send that recipients never receive. Last month we moved our System i email server to a collocation facility, which entailed changing the server's IP address. Everything seemed to be working fine, but now this problem has cropped up. The colo facility manager sees no connectivity or traffic problems, and we're receiving no bounce or other error messages. What would cause only certain messages to be... Read the rest of entry >>
Posted @ 09/01/2008 4:04 PM By Mel Beckman
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Dear Doctor,
We're moving to server virtualization and are planning for a Storage Area Network (SAN) array to provide disk storage for all our virtual machines. My problem is choosing between the two SAN technologies, Fibre Channel (FC) and iSCSI. I know iSCSI is newer, but FC is 4 Gbps versus iSCSI's 1 Gbps. FC costs more, but I don't want to saddle our virtualization effort with a slow storage solution unnecessarily. We will be running mission-critical database applications on the SAN, and... Read the rest of entry >>
Posted @ 08/01/2008 1:01 AM By Mel Beckman
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Dear Doctor,
Over the last few weeks, our users have seen an alarming increase in e-mail bounce messages that claim we are sending spam. The messages have subjects such as "Message rejected as spam" and "Message could not be delivered: policy reject." The thing is, they're definitely from legitimate companies, not spoofed. I immediately suspected some kind of spam-spewing virus on our network, but after a careful check of our intrusion detection system (which is great about flagging... Read the rest of entry >>
Posted @ 08/01/2008 1:01 AM By Mel Beckman
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Dear Doctor,
One interface on our System i box connects to an Ethernet switch that connects through a fiber-optic transceiver (FOT) and cable that runs 3,000 feet to our training center, where another FOT turns the signal back into Cat-5e that plugs in to another Ethernet switch. We sometimes need to unplug PCs from our main building and take them to the training center for special classes. Often when we do this, the PCs won't communicate to our System i server over the fiber, yet they can... Read the rest of entry >>
Posted @ 07/01/2008 1:01 AM By Mel Beckman
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Dear Doctor,
Our primary T1 Internet provider has frequent outages, so we're in the process of adding a second upstream Internet provider and will be running the Border Gateway Protocol (BGP) to provide automatic failover between the two providers. I have acquired the necessary Class C IP address space and the Autonomous System Number (ASN), and I have already set up BGP with our existing provider. Our new provider's circuit won't be installed for several weeks, but everything is configured on... Read the rest of entry >>
Posted @ 07/01/2008 1:01 AM By Mel Beckman
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Dear Doctor,
We're a total i5/OS shop and run several different kinds of mail servers: Lotus Notes, CommuniGate Pro, and the native i5/OS SMTP server. Each server provides e-mail for a specific suborganization of our enterprise. Recently, we've had a strange problem that affects all three servers: Incoming mail messages occasionally get duplicated, or worse. I've seen up to six copies of the same message. I see no pattern in where the duped messages originate, and with three completely... Read the rest of entry >>
Posted @ 06/01/2008 4:00 PM By Mel Beckman
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Dear Doctor,
Our VoIP system has two kinds of trunk connections to the local exchange carrier (LEC): an ISDN PRI T1 circuit with six channels for long distance and another four plain old telephone service (POTS) analog voice lines used for local calls. We're charged by the minute for both local and long distance on the ISDN PRI, while there are no per-minute charges on the POTS lines for local calls. The problem is that calls through the POTS lines suddenly have a terrible echo on them. The... Read the rest of entry >>
Posted @ 06/01/2008 3:54 PM By Mel Beckman
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Dear Doctor,
I installed a Voice over IP (VoIP) phone system for our office, initially set up to use Internet VoIP trunks. The reliability and sound quality of Internet phone calls was too poor for our management's taste, so I switched to Plain Old Telephone Service (POTS) analog lines. Alas, to my surprise, we still have significant sound-quality problems. The worst is that the beginning and ending of every spoken sentence seems to be clipped off. But we also hear a distinctive hiss that is... Read the rest of entry >>
Posted @ 05/01/2008 4:28 PM By Mel Beckman
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Dear Doctor,
Our remote offices' Windows servers nightly perform file copy operations from our central System i server for database synchronization. Recently, however, the file copy operations have begun randomly failing. Some nights they all work, but other nights one or more copies fail, with Windows giving the inexplicable error "timeout occurred." We have plenty of bandwidth, and other non-Windows copies running in parallel prove that network outages aren't occurring. Packet captures at... Read the rest of entry >>
Posted @ 05/01/2008 4:27 PM By Mel Beckman
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