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Carrier Routing System (CRS-1) Overview

We have finished the physical installation of our CRS-1 routers this week, so I thought it would be nice to have some discussions about CRS-1, Juniper T-series and some general high end platform concepts. I believe this will be a series of posts, we can start with the CRS-1 overview.

The CRS-1 is a carrier class router as its name implies, it comes in 4, 8  and 16 slots chassis. The system can be configured as a single or multi-shelf system (Currently only 16 slots supports multi-shelf configuration).

A single-shelf system delivers 4, 8, or 16 40-Gbps line-card slots and can reach a switching capacity of 1.2 Tbps in a 16 slot box. System capacity can be increased without service interruption in 1.2-Tbps increments by adding extra shelves to the system.

The CRS-1 router is typically used in service provider core networks as a P router in MPLS environments, it can also be used for aggregation or rarely as an edge router in consolidated POPs.

CRS-1 hardware components include the chassis, route processors, switch fabric cards, Physical layer interface modules (PLIMS), Modular service cards (MSCs), power units and fan trays.

CRS-1 is using a new operating system called IOS-XR instead of the known IOS (Modular vs Monolithic OS). It is a distributed processing operating system designed. Cisco IOS XR Software is built on a preemptive, memory-protected, multitasking, microkernel-based operating system architecture that provides the process and thread distribution necessary to take advantage of the distributed-processing, multiple-CPU architecture found in the Cisco CRS-1.

In the Cisco IOS XR Software, features can be loaded and unloaded dynamically; processes reside in their own protected memory spaces, they can be restarted, and they communicate with each other through an advanced, reliable message-passing mechanism.

The router offers high level of hardware redundancy and high availability features. It contains redundant route processors, power suppliers, fan trays and the switch fabric cards.

that’s all  for this post in future posts we will get into more details about the box  hardware and software architectures.

External Resources:

crs1 Cisco Carrier Routing System

Cisco CRS-1 Multishelf System

Carrier Routing System-Wikipedia

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