Tech Library
OSPF Neighborship Requirements and Troubleshooting
1. Intro It is often times a struggle to bring up an OSPF Neighborship between two routers. Well, it can be if you don’t clearly know all requirements. In this post we will see all OSPF neighborship requirements and how to troubleshoot when the neighbors are not UP. As a network engineer we must know […]
Protect RE – Configuring the Protect RE Filter
Intro In this post we will configure firewall filters to control traffic destined to the Routing Engine. As mentioned in the previous post, Common Network Protocols, we must know how the protocols work, how they are transported through the network, and how you can match them in the firewall filter. But before starting with the […]
ISIS Overload timeout – Testing the timeout knob
1. Intro First of all, lets quickly review the what the official documentation is saying about the ISIS overload timeout knob: You configure or disable overload mode in IS-IS with or without a timeout. Without a timeout, overload mode is set until it is explicitly deleted from the configuration. With a timeout, overload mode is […]
ISIS Overload – Learn with a practical example
1. Intro The Overload statement causes the routing device to continue participating in IS-IS routing, but prevents it from being used for transit traffic. It is useful sometimes to deviate the traffic away from a particular router, so we can avoid traffic being impacted. We typically have 2 scenarios: Bonus scenario: ISIS will make this […]
ISIS – PDUs and Wireshark sample packets
Intermediate systems send and receive packets and relay (forward) packets. ISO packets are called ISIS Protocol Data Unit packets, or in short ISIS PDU. There are four PDU types and all share a common header. This common header has the same structure and information for all four PDU types, except the ‘PDU Type’ filed as […]
Protect RE – Common Network Protocols
Protect RE (Routing Engine) is a Juniper Networks security best practice that uses a stateless firewall filter on the loopback interface (lo0) to secure the control plane. It restricts management traffic (SSH, SNMP) to trusted sources and protects the CPU from malicious traffic or resource exhaustion (e.g., DoS attacks). Key Aspects of Protect RE on Juniper […]