Juniper

In this post, we will look at how to troubleshoot BGP establishment on Junos. First, we will look at what tools are available. Then, we will look at some common examples of why BGP might not be established This follows on from the posts on general BGP establishment troubleshooting and the basics of how to […]

This post will focus on the manual backup of Junos configuration files. Many networks will use a Network Management System (NMS) or a scripting solution like Ansible or Rancid to perform daily backups of network devices. You can also use the archival command to have Junos automatically backup the configuration every time a commit is

When we advertise a BGP route to an eBGP neighbor, it is common to remove any private AS numbers that are in the AS path. One reason to do this is to hide any complexity within our network so our eBGP peers only see our public AS number in the path. On Junos, this can

On Junos, we can limit the number of prefixes, or routes, that a BGP neighbor can advertise to us. We can choose what to do when we receive too many routes. We can start logging messages or we can tear down the BGP session. Sessions can be torn down for a set amount of time

On Junos, only active BGP routes are advertised to peers. If we want to change this behavior we need to set the advertise-inactive BGP knob. The following example walks through this process. Lab Environment The lab is set up as per the below diagram. Lab Baseline On vMX-2 we have four BGP routes being learned

Local Preference is used to choose the best path out of our network. It is typically applied to inbound route advertisements to influence how traffic leaves our network. The local preference attribute is advertised over iBGP to other routers within our AS. On Junos, local preference is configured using a routing policy. We will see

AS prepending is used to artificially increase the length of the AS Path attribute. It is typically applied to outbound route advertisements to influence how traffic enters our network. On Junos, AS Prepending is configured using a routing policy. We will see how to do this in the following examples. Lab Environment The lab is

In this post, we will look at configuring VLANs, trunk ports, and IRB (or VLAN) interfaces on Junos devices. The IRB interfaces are layer 3 interfaces for VLANs and are the same as Cisco VLAN or SVI interfaces. The commands here are based on the Enhanced Layer 2 Software (ELS) style of CLI which is

In this post, we will look at some basic BGP configurations on Junos. Lab Environment The lab is set up as per the below diagram. Junos Default BGP Policy First, here is a quick refresh on the default Junos BGP policy. The default import policy will accept BGP routes from configured peers and import them