LDP Identifiers

I recently found myself in an interesting discussion regarding MPLS LDP. More specifically LDP identifiers, along with some interesting corner cases and caveats–depending on your IGP of choice and the scale of your network. I thought I’d write a post attempting to subjectively answer the following question.

Does LDP need an Identifier derived from an IPv4 address with a /32 network mask to work?

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LDP Over RSVP-TE

Considering the available label distribution protocols in MPLS networks, RSVP-TE and LDP are the de-facto standards. LDP is quite popular, however, one of its main limitations is the lack of traffic engineering support–ignoring CR-LDP for now. Sometimes even small networks can benefit from steering traffic one way or another to avoid potential congestion scenarios and/or underutilised links. This post looks at how LDP over RSVP-TE works in small Juniper MX core network deployment primarily running LDP as its main label distribution protocol.

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AToM Pseudowire Emulation

When it comes to MPLS, undoubtedly virtual private network (VPN) is one of its most popular and successful applications. Any Transport over MPLS (AToM) or L2VPN as it’s sometimes referred to allows customers’ sites to be interconnected at a Layer 2 level over the carrier’s MPLS backbone whilst supporting numerous different access technologies such as Frame Relay, ATM, PPP and Ethernet. Although some of these are considered legacy and are rarely encountered in modern network deployments, they still exist in some production environments scattered across the globe.

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IS-IS OL Bit. Avoiding Traffic Black-hole.

This post introduces the IS-IS LSP Database Overload Bit and how it can be used to avoid traffic black-whole during certain transient network conditions. It includes a sample scenario where such issue might occur along with the relevant tests and verification used throughout. Taking full advantage of the opportunity, it briefly demonstrates how IS-IS handles older LSPs on point-to-point links.
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CLNS and CLNP. What Is The Difference?

The best way I’ve found in order to understand the differences between CLNS and CLNP was to step back a bit and briefly go over some of the networking fundamentals including basic data network communication whilst at the same time trying to correlate any of these ISO terms to the little I know about TCP/IP.

In that way, with some luck, I could create a mental link between the two and hopefully facilitate the learning process. Haven’t we looked at the OSI and TCP/IP models for ages now in an attempt to break down the more complex parts of data communication in bits so we can digest and understand? Well, let’s give it a go.

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IS-IS or Integrated IS-IS?

If you’re new to IS-IS you might have come across different people, posts and or different documentation referring to it as IS-IS or Integrated IS-IS among others. This post very briefly attempts to introduce and clarify why that might be the case if you ever wondered.
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Tracked List and Boolean Expression

Enhanced Object Tracking or EOT can be very useful to meet specific task requirements you just can’t otherwise or at least not without a great deal of effort. This post briefly looks at a practical example on how to advertise a route, but only if specific requirements are met using EOT.

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Configure Replace For Lab Sessions

The configure replace command is a very neat feature which can save a lot of time during lab sessions. When I started doing some home grown labs I used to waste a lot of time getting the gear ready. All I wanted was to set all devices to a blank or to a particular base line configuration I had saved in flash so I could do some magic.

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