The authentication for OSPFv3 differs from OSPFv2. OSPFv3 does not use the authentication types of simple or MD5. Instead, an IPSEC Security Association (SA) is created. This can use AH to authenticate the OSPFv3 traffic or ESP to encrypt it. Lab Environment This lab uses two vJunos Routers connected via ge-0/0/0. The relevant baseline configuration […]
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On Junos, both OSPF and IS-IS have an overload setting. Although they perform a similar function, they achieve this through different methods. This leads to slightly different results when applying the overload setting. Note: Cisco does not have an overload command for OSPF. Instead, it has the ‘max-metric router-lsa’, which does a similar job. Why
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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
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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
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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
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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
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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
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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
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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
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It can be difficult to troubleshoot the establishment of BGP sessions. Sometimes the issue is obvious, but other times it can be a vague and frustrating process. In this post, we will run through some of the tools available, the BGP Finite State Machine (FSM), and a general approach for troubleshooting BGP establishment. BGP Troubleshooting
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