Bandwidth monitoring hasn’t been as big a concern for as long as some of us might think. Ethernet was founded in 1973 by Bob Metcalfe and David Boggs. Read more »
Michael PattersonMost people collecting NetFlow use it in a very traditional fashion (i.e. NetFlow v5 with ingress flows). Ingress flow means that only inbound (i.e. received) traffic is collected and exported in NetFlow datagrams. This may sound like you won’t know what is going ‘out’ an interface, but have no fear. There is any easy way to calculate outbound traffic using ingress NetFlow.
Above, out bound utilization on interface 1 is determined by looking at the flows from interfaces 2,3 & 4 that are destined for interface 1. Since an ingress flow contains the source and destination interface (i.e. port of the router). Out bound traffic is determined by using ingress flows from the other interfaces. For this reason, it is important to enable NetFlow on all interfaces of the switch or router. This trick is common practice in all NetFlow reporting tools. But, what about NetFlow v9 and its support for ‘Egress’ NetFlow (i.e. traffic going out an interface)?
When was the last time you used a Network General Sniffer™? Do you remember the Matrix view? Read more »
Michael PattersonThe top security threat in enterprise environments during the first half of the year was the Conficker worm, Microsoft says in its Security Intelligence Report (SIRv7), which covers the first six months of 2009. Read more »
Michael PattersonPlease read Part 1 of this blog first.
Why Service Providers need 95th Percentile
In an attempt to keep prices competitive and attract new customers, some service providers make efforts to bill customers based on usage. This is how the 95th percentile became standard practice. Here is how it works: A customers bandwidth is measured (or sampled) from the switch or router and recorded in a log file. In many cases, this is done every 5 minutes. At the end of the month, the samples are sorted from highest to lowest and the top 5% (which equal to approximately 36 hours of a 30-day billing cycle) of data is thrown away. The next highest measurement becomes the billable utilization for the month. Read more »
Networks tend to evolve over time. Over the past 5 – 7 years, I have seen VoIP and video push many network administrators to think beyond utilization and latency. Prioritization is an important part of the mix today. Although trying to absolutely guarantee QoS with Network traffic is impossible, it is possible to prioritize critical data and increase delivery time probabilities. Read more »
Michael PattersonAs much as I would like to see more companies switch over to IPv6 it isn’t going to happen overnight. Like anything involving an expensive migration process, you should ask yourself some questions.
When do businesses need to move to the new system and what are the advantages of switching over to IPv6? Why make the move? I don’t think you have to but, be aware that IPv6 use has grown by 300% over the past 2 years. Read more »
Many NetFlow Reporting applications claim to tell you who the top 10 bandwidth hogs are by displaying the top 10 or so hosts for a time period based on total amount of traffic sent or received. Yes, this is helpful but it can paint a distorted picture when it comes to network traffic analysis. What about Flow Volume? Read more »
Michael PattersonVirtual routing and forwarding (VRF) is a technology included in IP (Internet Protocol) network routers that allows multiple instances of a routing table to exist in a router and work simultaneously. This increases functionality by allowing network paths to be segmented without using multiple devices. Because traffic is automatically segregated, VRF also increases network security and can eliminate the need for encryption and authentication. Internet service providers (ISPs) often take advantage of VRF to create separate virtual private networks (VPNs) for customers; thus the technology is also referred to as VPN routing and forwarding. Read more »
Michael Patterson