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3 Ways to Build Your Network: A Primer on Network Switching Choices

By Sreeram Krishnamachari, Global Product Line Manager, HP Networking


Stacks, stacks and more stacks

“Stacking” is a ubiquitous term in switching. It often means different things to different people. Most commonly understood meaning of this term is that it helps virtualize multiple switches into a single switch.




We all like choices in life. In building a network, it is good to have a choice of technologies that can be implemented based on specific environments. HP offers your three different choices based on the desired use model:

• HP Intelligent Resilient Framework (IRF)
• HP Mesh Stacking
• HP Switch-to-Switch “Distributed Trunking” (DT)

Let’s dive in.


HP Intelligent Resilient Framework


HP IRF is a widely deployed unified fabric solution. With IRF, up to 9 fixed port switches and 4 modular switches can be virtualized and managed as a single switch. (Table 1:IRF support matrix).




   Table 1: Technology product support matrix


IRF uses standard 10G ports to stack and hence can use single mode fiber to create a common fabric between switches that are up to 72km apart. IRF, for example, is very useful in virtualizing cores of two campuses or data centers that are geographically dispersed.  Customers enjoy the benefit that comes from the simplicity of collapsing multiple switches into a single control plane and UI. Less than 50ms resiliency in IRF enables the stack to continue to operate when one of the switches in the stack fails. Ring and chain are the supported topologies. Using IRF, spanning tree and VRRP can be avoided.


HP Mesh Stacking


The Mesh Stacking was introduced as part of the newly released HP E3800 Switch Series. With mesh stacking, up to five 3800 switches can be connected in a mesh and up to 10 switches can be stacked in a ring or a chain. Being the first in the industry, mesh stacking makes the back plane of the stack look like the crossbar fabric of a chassis and hence offers superior resiliency and lower latency than a traditional ring topology.




These switches use high performance links on the back plane that can deliver up to 336Gbps of bi-directional backplane performance. Due to these high performance cables, the stacking links are currently limited to 3m in length. Similar to IRF, Mesh Stacking helps network managers to remove spanning tree, enjoy single UI and control plane and fast resiliency when a switch fails.

HP Distributed Trunking

HP switch-to-switch Distributed Trunking (DT) enables LACP across switch boundary. HP DT prevents data path failure in north-south traffic even if a switch in the middle fails. (Figure 3). IRF and Meshed stacking which offer both L2 & L3 redundancy but DT this is primarily an L2 technology. When both the switches are alive, both the upstream links act as LACP trunks and are active but when one of the switches fails the connection from the edge to the core is retained even though the traffic flows only through one of the links. All switches in the Distributed Trunk retain their individual UIs and control plane. Unlike IRF and Mesh Stacking, two switches from different product families can be part of DT. 

A summary of this discussion can be found below in table 2.


table 2.jpg

  Table 2


So which stack do you want to create?


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angelcruzpr | ‎01-02-2014 01:59 PM

Being new to HP Networking I had a hard time figuring out the difference between IRF and Distriguted Trunking.


This articles nailed it!



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