Cisco ASR
By Cisco
Cisco ASR, short for Aggregation Services Router, is a family of carrier-grade routers from Cisco built to handle high volumes of network traffic at the aggregation points of service provider and large enterprise networks. ASR routers sit…
Definition
Cisco ASR, short for Aggregation Services Router, is a family of carrier-grade routers from Cisco built to handle high volumes of network traffic at the aggregation points of service provider and large enterprise networks. ASR routers sit between access networks and a provider's core network, aggregating traffic from many downstream connections and applying routing, security, and quality-of-service policies at scale.
Overview
Internet and telecom service providers need routers positioned between their core backbone and the many individual access connections feeding into it, capable of aggregating traffic from thousands of downstream customers or cell sites while applying routing decisions and traffic policies without becoming a bottleneck. Cisco built the ASR line specifically for this aggregation role, distinct from its smaller branch-office and campus router products. ASR routers use specialized forwarding hardware, often built around custom silicon, to route packets at very high throughput while simultaneously running services like traffic shaping, encryption, and multiprotocol label switching that let a provider carve its network into isolated virtual paths for different customers or services. Because ASR platforms sit at aggregation points, they are engineered for high availability, supporting redundant hardware components and software features that allow configuration changes or even software upgrades without dropping the traffic passing through them, a requirement that smaller enterprise routers typically do not need to meet. Within Cisco's router portfolio, ASR sits above branch and campus routers in scale and below Cisco's largest core routers built purely for backbone traffic aggregation across an entire carrier network. Compared to Cisco's data-center-focused Nexus switches, ASR routers perform layer-3 routing and traffic engineering across wide-area links rather than switching traffic between servers inside a single facility. Telecom carriers deploy ASR routers at points where they aggregate traffic from cell towers, business customer connections, or regional access networks before it enters their core backbone, while large enterprises with extensive wide-area network footprints use smaller ASR models to aggregate branch-office traffic at regional hub sites before it reaches a company's data centers or cloud connections. Because ASR routers are built for carrier-scale aggregation, they carry a cost, power, and space footprint that is unnecessary and impractical for smaller networks, meaning the product line is generally not a fit outside service provider and large enterprise wide-area network deployments. Configuring and operating ASR routers also requires network engineering expertise in carrier routing protocols and traffic engineering concepts that go well beyond what typical office network administration requires. Provisioning and troubleshooting an ASR deployment typically falls to specialized service provider network engineering teams rather than general IT staff, and the operational discipline required to change configuration on a live carrier aggregation point without disrupting subscriber traffic is itself a significant part of why these platforms carry a steep learning curve for engineers moving over from general enterprise networking roles.
Key Features
- Custom forwarding silicon for high-throughput carrier-grade routing
- Multiprotocol label switching support for virtual network path isolation
- Redundant hardware components supporting high-availability operation
- In-service software upgrade capability without dropping active traffic
- Traffic shaping and quality-of-service policy enforcement at aggregation points
- Positioned between access networks and carrier core backbone infrastructure
- Range of models scaling from enterprise wide-area aggregation to carrier-scale deployment