Migration Strategy: Moving From MPLS/LDP to Segment Routing

21 03 2019

MPLS core networks that use Label Distribution Protocol (LDP) are common in SP core networks and have served us well. So, the thought of pulling the guts out of the core is pretty daunting and invites the question why you would want to perform open-heart surgery on such critical infrastructure.   This article attempts to explain the benefits that would accrue from such a move and gives a high-level view of a migration strategy.

Why Do I Need Segment Routing?

  • Simplicity:   LDP was invented as a label distribution protocol for MPLS because nobody wanted to go back to the standards bodies to re-invent OSPF or IS-IS so that they could carry labels.  A pragmatic decision, but one that results in networks having to run two protocols.  Two protocols means twice the complexity.  
    Segment Routing simplifies things by allowing you to turn off LDP.  Instead it carries label (or Segment ID) information in extensions to the IGP.  This then leaves you with only IS-IS or OSPF to troubleshoot.  As Da Vinci reportedly said, ‘simplicity is the ultimate sophistication’. 

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Cisco CRS-1 Rack and Stack

28 06 2007

I’m just on a Cisco CRS-1 Essentials course this week, which has been pretty interesting all round We had a peek inside their NGN test-lab at 300 Longwater Avenue this afternoon for a look at the physicals of the box itself, and man – it’s a beast.

For a start, they recommend you need three people for two days to install this thing (the 16-slot version). It comes in so many boxes you wouldn’t believe, so for a start you need to plan where it’s all going to go while you get the chassis inside.

The chassis itself can weigh 1800 pounds in total, so you need to re-inforce the floor all the way to its final resting place. You also need to make sure the thing will fit through all the doors – it seems to be about 7 feet high, and you don’t want to be tipping something like that over to get it in a lift. Read the rest of this entry »