Network

bing An alert is coming in, but unfortunately your network is unreachable. What now? How would you fix this problem when you can't access your network? You don't want to go to the datacenter, because you're a RelaxOps (tm)! Good that you are prepared

Some network services are predestinated to be used as DDoS helper: They are UDP based and the response payload is much bigger than the sent request. UDP makes it easy to fake the sender IP. So anyone can send a request on behalf of some other IP which then gets

An introduction into LLDP What is LLDP? LLDP is a network layer 2 protocol, called "Link Layer Discovery Protocol". It transmits many information about the device and ports to all network neighbors. It is vendor independent and specified in IEEE 802.1AB [http://standards.ieee.org/getieee802/download/

There can be some situations where you need to create a redundant link between two switches/routers (f.e. between a Cisco and a Brocade device) where you are not able to use STP which takes care of a loop-free configuration and failover handling. Cisco has this nice little feature

As I find it a very unintuitive way to set the "Port Native VLAN" on a Brocade switch, I just want to share this with the world. And this is how to set the "Port Native VLAN" on an interface: interface ethernet <your interface>

For BGP traffic engineering it's very important to know which Destination-AS takes which path on your Upstream links. There is a great tool to visualize this: as-stats [https://neon1.net/as-stats/]. It's too bad that this nice piece of software lacks some very important things: There

Rancid [http://www.shrubbery.net/rancid/] is a great tool to regularly save configs of network devices in SVN such as routers and switches. There are many how-tos for installing and configuring this tool (so I don't have to re-invent the wheel): * Linux Home Networking [http://www.linuxhomenetworking.

To send Syslog messages to Observium with Logstash, you can do it like described on this article (it's not perfect, but it works). The first thing you have to do is to define an IOS filter in Logstash. This is how it looks like: filter { ### IOS Grok grok