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Interchassis Redundancy and Virtual Chassis Overview

 

As more high-priority voice and video traffic is carried on the network, interchassis redundancy has become a baseline requirement for providing stateful redundancy on broadband subscriber management equipment such as broadband services routers, broadband network gateways, and broadband remote access servers. To provide a stateful interchassis redundancy solution for MX Series 5G Universal Routing Platforms, you can configure a Virtual Chassis.

This topic provides an overview of interchassis redundancy and the Virtual Chassis, and explains the benefits of configuring a Virtual Chassis on supported MX Series routers.

Interchassis Redundancy Overview

Traditionally, redundancy in broadband edge equipment has used an intrachassis approach, which focuses on providing redundancy within a single system. However, a single-system redundancy mechanism no longer provides the degree of high availability required by service providers who must carry mission-critical voice and video traffic on their network. Consequently, service providers are requiring interchassis redundancy solutions that can span multiple systems that are colocated or geographically dispersed.

Interchassis redundancy is a high availability feature that prevents network outages and protects routers against access link failures, uplink failures, and wholesale chassis failures without visibly disrupting the attached subscribers or increasing the network management burden for service providers. Network outages can cause service providers to lose revenues and require them to register formal reports with government agencies. A robust interchassis redundancy implementation enables service providers to fulfill strict service-level agreements (SLAs) and avoid unplanned network outages to better meet the needs of their customers.

Virtual Chassis Overview

One approach to providing interchassis redundancy is the Virtual Chassis model. In general terms, a Virtual Chassis configuration enables a collection of member routers to function as a single virtual router, and extends the features available on a single router to the member routers in the Virtual Chassis. The interconnected member routers in a Virtual Chassis are managed as a single network element that appears to the network administrator as a single chassis with additional line card slots, and to the access network as a single system.

To provide a stateful interchassis redundancy solution for MX Series 5G Universal Routing Platforms, you can configure a Virtual Chassis. An MX Series Virtual Chassis interconnects two MX Series routers into a logical system that you can manage as a single network element. The member routers in a Virtual Chassis are designated as the Virtual Chassis master router (also known as the protocol master) and the Virtual Chassis backup router (also known as the protocol backup). The member routers are interconnected by means of dedicated Virtual Chassis ports that you configure on Modular Port Concentrator/Modular Interface Card (MPC/MIC) interfaces.

An MX Series Virtual Chassis is managed by the Virtual Chassis Control Protocol (VCCP), which is a dedicated control protocol based on IS-IS. VCCP runs on the Virtual Chassis port interfaces and is responsible for building the Virtual Chassis topology, electing the Virtual Chassis master router, and establishing the interchassis routing table to route traffic within the Virtual Chassis.

Note

MX Series Virtual Chassis does not support Ethernet OAM, distributed inline connectivity fault management, Ethernet frame delay measurement, loss measurement, synthetic loss measurement, and Ethernet alarm indication signal (ETH-AIS).

Benefits of Configuring a Virtual Chassis

Configuring a Virtual Chassis for MX Series routers provides the following benefits:

  • Simplifies network management of two routers that are either colocated or geographically dispersed across a Layer 2 point-to-point network.

  • Provides resiliency against network outages and protects member routers against access link failures, uplink failures, and chassis failures without visibly disrupting attached subscribers or increasing the network management burden for service providers.

  • Extends the high availability capabilities of applications such as graceful Routing Engine switchover (GRES) and nonstop active routing (NSR) beyond a single MX Series router to both member routers in the Virtual Chassis.

  • Enables service providers to fulfill strict service level agreements (SLAs) and avoid unplanned network outages to better meet their customers’ needs.

  • Provides the ability to scale bandwidth and service capacity as more high-priority voice and video traffic is carried on the network.

Supported Routing Platforms for MX Series Virtual Chassis

You can configure a Virtual Chassis on the following MX Series 5G Universal Routing Platforms with MPC/MIC interfaces:

  • MX240 Universal Routing Platform

  • MX480 Universal Routing Platform

  • MX960 Universal Routing Platform

  • MX2010 Universal Routing Platform

  • MX2020 Universal Routing Platform

Note

Platform support depends on the Junos OS release in your installation.

Graceful Routing Engine switchover (GRES) and nonstop active routing (NSR) must be enabled on both member routers in the Virtual Chassis.

Supported Member Router Combinations

A two-member MX Series Virtual Chassis supports the member router combinations marked as Yes in Table 1.

Table 1: MX Series Virtual Chassis Supported Member Router Combinations

Member Router Type

MX240

MX480

MX960

MX2010

MX2020

MX240

Yes

Yes

Yes

No

No

MX480

Yes

Yes

Yes

No

No

MX960

Yes

Yes

Yes

Yes

Yes

MX2010

No

No

Yes

Yes

Yes

MX2020

No

No

Yes

Yes

Yes

Routing Engine Requirements

Each member router in the Virtual Chassis must have dual Routing Engines installed, and all four Routing Engines in the Virtual Chassis must be the same model. For example, you cannot configure a Virtual Chassis if one member router has two RE-S-2000 Routing Engines installed and the other member router has two RE-S-1800 Routing Engines installed.

Note

For an MX Series Virtual Chassis configuration that includes an MX2020 router, all four Routing Engines in the Virtual Chassis must have at least 16 gigabytes of memory.