Author: René Jorissen
Cacti, easy going
A decent management server is very important in a network, at least that is my opinion. The most important aspect of a management server is its user friendliness. Our customers are most of the time busy with their own problems and the problems of end users, which include all kind of (silly) problems. So the … Read More
Port-channel Cisco vs. VMware ESX
I have had different discussions with different customers about the load-balancing algorithms between a Cisco switch, configured with a port-channel and a VMware ESX server using multiple NICs. Our VMware consultants always choose Route based on IP hashes as load-balancing algorithm. This means that load-balancing happens on layer 3 of the OSI model (source-destination-IP). In … Read More
Anti-virus / Anti-SPAM, Mail relaying
Barracuda User Creation
I have a customer running a Barracuda SPAM firewall 300. The customer has the specific request that only the administrator can look at Quarantine messages and users shouldn’t get their own Quarantine inbox. To accomplish this I have configured the Quarantine Type: Global. I see that all Quarantine messages are delivered in the globally configured … Read More
relays.ordb.org
Since the day before yesterday, some of our customers complained having problems with receiving e-mail. The senders from the e-mail noticed that their mail had been blocked by relays.ordb.org. This RBL is offline, according to this article, at least everybody thought. Seems to me, the RBL came online yesterday and blocked everything. I have heard … Read More
ProCurve excessive STP topology changes
Recently a colleque of mine noticed something strange in the STP configuration from a couple of HP ProCurve switches. He had a network, which was configured by another party, with switches running MST en RSTP mode spanning-tree. He noticed a lot of topology changes in the configuration, but couldn’t find out where they were coming … Read More
NTP Configuration
The right time synchronization is very important while troubleshooting different kind of problems. Most network components have the option to synchronize their time with a time server on the internal network or the internet. This post shows how to configure NTP with the right time zone on Cisco and HP ProCurve components. The example configurations … Read More