Cisco-Layer 2 Resiliency Compared to HP’s IRF Essay.
In order to provide speed and reliability, large and enterprise-level networks today are typically constructed in multiple layers. They are the access layer, also called the network edge layer, the aggregation or distribution layer; and the network core layer. The access layer is usually a mesh of network switches, linked to other switches in the aggregation layer, which in turn is linked to the core. This mesh type application of switches provides multiple paths for network traffic to flow. What this means is that if one link in the traffic flow or a switch goes down, traffic can continue to flow using an alternate path.
This type of mesh interlinked switches uses Spanning Tree Protocol (STP) to detect and prevent loops. A loop occurs when there are multiple active paths to the same switch and this causes the system to crash. Some advantages of HP’s IRF Resiliency are higher efficiency with IRF’s loop-free, non-blocking architecture.
This is designed to keep all links active, enabling highly efficient, high bandwidth connectivity throughout the switching plane.
Scalable performance is achieved with IRF and Link Aggregation Control Protocol (LACP). When used together, they can boost performance by bundling several parallel links between switches and servers, allowing scalable “on-demand” performance and capacity to support critical business applications. HP’s IRF Resiliency offers faster failover in the event a network failure occurs; IRF can deliver rapid recovery and network re-convergence in fewer than 50 milliseconds—much faster than the several seconds required for STP.
The disadvantages associated with HP’s IRF Resiliency are said to be poor performance because it blocks all parallel paths except the one it has selected as active. Technicians have complained that even when the network is operating normally STP actually reduces the effective bandwidth. Some people claim that the choice of which protocol to use is difficult and that there is a slow network convergence. One problem is that the re-convergence time for STP can be several seconds.
In contrast, Cisco Layer 2 Resiliency advantages are claimed to offer rapid failover without service disruption. The layer 2 is designed to streamline change management and service turn-up without WAN disruption with fewer errors. It offers a high availability through real-time recovery and resiliency at the network, device and design levels. Cisco Layer 2 Resiliency offers increased system redundancy at the platform level, network security through access layer defense, identity-based trust, pervasive security and management as well as providing device posture assessments. Operational efficiency is achieved through automated configuration, proactive diagnostics and simplified troubleshooting. This is designed to provide predictable application performance to support converged applications as well as support IP multicast for new applications.
As with HP’s IRF Resiliency, there are several disadvantages associated with Cisco Layer 2 Resiliency. The router supports REP only when the router is running the metro IP access or the metro access image. You have to configure each segment port or an incorrect configuration will cause forwarding loops in networks. REP can only manage one failed port within a segment. Multiple port failures within the REP segment cause high loss of network connectivity.
Due to its simplistic manageability and scalability I would recommend HP’s IRF Resiliency over Cisco Layer 2 Resiliency. Due to the limitations of Cisco Layer 2 Resiliency, HP’s IRF Resiliency is a technology that will provide a network that is fully resilient, yet is also simpler to set up and manage. At the same time it uses the full capabilities and bandwidth of each switch, ensuring greater overall efficiency in networking infrastructure. HP’s IRF Resiliency allows an organization to incorporate their existing switches and network with HP IRF switches to provide a seamless migration.
Cisco Unified WAN Services: Services, Security, Resiliency, and Intelligence – Cisco. (n.d.). Retrieved from http://www.cisco.com/en/US/prod/collateral/routers/ps9343/solution_overview_c22-450358_ps9343_Products_White_Paper.html Resilient Services Solution for Campus Network – Cisco. (n.d.). Retrieved from