Juniper

Running a shell script during boot on Junos

I had recently to work on a situation where specific Junos configuration had to be applied on a device after reboot as a workaround. There are multiple solutions to this problem and the simplest one is to create a shell script that crontab will run after reboot. However, you need to make sure that you… Keep reading »

GRE tunnel between Juniper and Linux

This is a short howto about how you can bring up a GRE tunnel between Juniper devices and Linux, Ubuntu in this case. Just to provide some basics about GRE tunnels: Each endpoint has to have reachability to the other endpoint One endpoint must use the GRE tunnel to reach the destination of the tunnel(recursive… Keep reading »

Subnet-Router Anycast address on Junos

In this post we are going to discuss Subnet-Router Anycast address and how it is configured on Junos. The Subnet-Router anycast address is covered here: https://tools.ietf.org/html/rfc4291#section-2.6.1 The anycast address is the same as the unicast address from the interface with the difference that the interface identifier is set to zero. Any router on the subnet… Keep reading »

Getting MAC addresses using SNMP on EX2300/EX3400

In this post we are going to see how you can extract the content of the MAC address table using SNMP on EX2300 or EX3400. This is different than some other switching platforms like EX4200, EX4500, EX8200. To accomplish this, different Juniper enterprise MIBs must be used. Let us see how we can achieve this…. Keep reading »

Snapshots on EX2300/EX3400

In this post I will discuss about snapshots on EX2300 and EX3400. While the new FreeBSD version used in Junos releases after 15.1 is not specific to EX2300/EX3400, I will discuss more about them because I had access to these devices when I captured the outputs. However everything is applicable to the other platforms like… Keep reading »

Excluding interfaces from IRB State Calculations

As you know, in order you have an IRB up, you need to have at least one interface up on the VLAN for which the IRB is created. This condition is sometimes forgot by engineers troubleshooting why an IRB or RVI or SVI(in Cisco terms) is down. By default all interfaces part of the VLAN… Keep reading »

Proxy ARP on Junos

In this post I will discuss about Proxy ARP feature on Junos, more exactly on EX4200 platform. When a host sends an ARP Request to a switch configured with Proxy ARP, the switch send its own MAC address to resolve the ARP for the destination host and the source host starts to used the switch… Keep reading »

Short Reach Mode on QFX5100-48T

In this post I will discuss about short reach mode feature that is present on QFX5100-48T platform. QFX5100-48T-6Q platform has 48 10BASE-T ports and 6 QSFP+ ports. The short reach mode feature allows to save up to 5W of power usage in case it is activated on the 10BASE-T ports that use cables that are… Keep reading »

Recovery installation on EX9200

The recovery installation is used to restore the factory default installation in case the device software gets corrupted. Once the software gets restored, the device will have the default configuration and it will be needed to either recreate manually the configuration that was running on the device prior the software corruption or to use a… Keep reading »

Health monitoring of hard drives in Juniper switches and routers

The are two ways to monitor the health of HDD in Junos: Using Self-Monitoring Analysis and Reporting Technology (SMART) system Using iostat Using the SMART system, HDDs incorporate a suite of advanced diagnostics that monitor the internal operations of a drive and provide an early warning for many types of potential problems. The SMART system… Keep reading »

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