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A virtual route reflector (vRR) removes reliance on dedicated hardware and offers more flexible deployment options and upgrades for improved scale and performance.
BGP route reflection: A perfect fit for virtualization
Border gateway protocol (BGP) route reflectors have been a key part of BGP networks for decades, to help eliminate the need for a full internal BGP mesh within an autonomous system. In today’s networks, the RR function is usually run on an IP router that is either dedicated for route reflection or that performs the RR function in addition to other IP routing and services functions.
A router used solely for RR functions is underutilized in the data plane because RR functions require minimal data-plane resources. Moreover, a router that shares the RR function with other IP routing functions may not have sufficient resources (CPU and memory) to support scalable route reflection.
In most cases, a higher end router platform may be required to support additional RR capabilities. In addition, some network operators may deploy separate RRs for specific BGP address families and applications, such as:
- Internet routing
- Layer 3 virtual private network (VPN)
- Layer 2 VPN
This increases costs related to deploying and scaling RRs.
RR operation is memory and compute-intensive and is well suited to run on x86-based server platforms. Virtualization removes reliance on dedicated hardware, which may lack sufficient performance and scale in the control plane and/or which may be underutilized in the forwarding path.
A vRR offers more flexible deployment options and upgrades for improved scale and performance. Scale and performance levels can be adjusted up or down as needed by flexibly allocating virtual machine (VM) resources to the vRR.
Virtual route reflector -- Implementation details matter!
Given that RRs are a perfect fit for virtualization, several vRR products are being offered by vendors today. But virtualizing an RR function is more than just compiling a software image to run on a virtualized x86 server. Key questions to consider are:
- Is the implementation based on proven and mature base software?
- Does the implementation take advantage of the underlying x86 server environments?
To meet the same level of stability and robustness that is offered today, virtualized network function implementations require a proven and stable software base optimized to operate within an x86 virtualized environment.
IT server virtualization technologies offer multicore (multi CPU) support and significantly larger memory capacity -- which can provide significant performance and scalability to the vRR function.
An implementation that supports parallel Symmetric Multi Processing helps unleash the power and performance of multi-core processing.This multi-threaded software approach offers concurrent scheduling and executes different processes on different processor cores. It significantly reduces route learning and route reflection times (route convergence times).
In addition, implementations that support 64 bit are better suited to address a larger memory space providing more scalability (support for increased number of BGP peers and routing entries).
Operators need to carefully consider the vRR solution and its implementation in order to get maximum benefits. Several service providers and enterprises/government organizations are currently evaluating virtual route reflector products, and some have moved to the live deployment phase. This early momentum and acceptance provides a positive proof point for the performance and scalability of virtualized routing applications.
Alcatel-Lucent is embracing virtualization for IP/MPLS service routing. Read the Alcatel-Lucent Virtualized Services Router – Router Reflector (VSR-RR) application note for additional details on how vRRs can raise the bar on performance and scale.
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