Five Reasons Classic Ethernet Switches Won’t Support the Cloud

When a company starts looking at providing cloud services to its clients, or consuming cloud services itself, it often becomes quickly apparent that the network needs to be upgraded to support this new service delivery model.

From an article: 
Five Reasons Classic Ethernet Switches Won’t Support the Cloud.
By Drew Robb

“External and hybrid cloud models mean that computing resources are remote, and access/ communications with those workloads will have to traverse a wide area or Internet network link,” says Jim Frey Managing Research Director of analyst firm Enterprise Management Associates. “This introduces substantially greater latency (and bandwidth constraints) than are normal for traditional campus/data center-based computing.”

Before implementing cloud computing, therefore, it is critical to examine the strength of the network to make sure that any weak points are located and eliminated. This helps to ensure …

1. Classic Ethernet Networks are Hierarchical

Ethernet typically relies on a hierarchy of three or more tiers. Moving traffic between different server racks, for example, requires transitioning up and down this logical tree. The important point here is that each step along the path adds to the total latency. To avoid bridge loops between different network segments, IEEE 802.1D Spanning Tree Protocol (STP) allows only one active path at a time between two switches. However, …

2. Classic Ethernet Networks are Unintelligent

Classic switches are designed to connect physical, not virtual, resources. Each port is individually configured with the QoS, security, VLAN traffic and other network policies required by that particular server. In a virtual world, however, VMs move from one box to another depending on traffic loads or maintenance requirements. Unless the port configuration follows the VM to its new physical location, …

3. Classic Ethernet Networks Don’t Scale

Since Classic Ethernet networks are designed to allow only a single connection between switches, this limits the amount of traffic they can carry.

“The scalability of traditional Ethernet is problematic, especially if an organization assumes, as it nearly always will, that cloud infrastructures will grow,” says Charles King, Principal Analyst at Pund-IT, Inc. “That said, …

To reduce the impact of this bottleneck, link aggregation groups (LAGs) permit multiple physical links to share the ISL. But this requires …

4. Classic Ethernet Networks Are Inefficient

Due to the limitations of STP, only one link or LAG can be active at a time, lowering the utilization rate. Adding or removing a new link causes the entire network to pause …

5. Classic Ethernet Networks Are Complex

With classic Ethernet networks, each port on each switch needs to be configured with the applicable VLANs, QoS, security, network policies and protocols. As servers are added, …

Switching to Fabric

To eliminate the various bottlenecks caused by traditional Ethernet architectures, switch vendors have begun to adopt fabric architecture into their Ethernet switches. This eliminates or mitigates each of the problems listed above.

Fabric switches flatten the network, reducing latency by eliminating unnecessary steps and preventing bottlenecks …

Classic or Fabric?

When is a classic Ethernet network adequate and when should one change to an Ethernet fabric? It depends on the applications. Some applications require large amounts of raw throughput; transaction systems are sensitive to latency.

“It comes back to what is the workload one is trying to project up into the cloud,” says Dan Kusnetzky, analyst and founder of the Kusnetzky Group. “Until we know more about the application and its requirements, … Ultimately, though, some network upgrades and enhancements will be in your future.”


Read the entire article: 
Five Reasons Classic Ethernet Switches Won’t Support the Cloud.
By Drew Robb

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