Which Cisco SFP is Right Between SFP-GE-T and GLC-T?

One great thing about the SFP/SFP+ standard is that it lets single pieces of networking hardware support a range of different cabling standards. Instead of having to get a new switch you can just swap out the optical transceivers as different transceivers handle different connections and cabling.

There is a downside though; there’s an astonishing amount of SFP transceivers out there for Cisco, and indeed other brands. They all have only the smallest differences between them.

Even a seasoned professional will have to check the tech sheets to understand which is the right one of them. It’s hardly surprising that one of the questions we get asked the most about Cisco SFP transceivers is what the difference between SFP-GE-T and GLC-T standards are. The answer, basically, amounts to “not much”.

Telling the Difference Between Cisco GLC-T SPF and Cisco SPF-GE-T Formats

When taken as they are, the two formats seem fairly similar and can be interchangeable most of the time. Both formats are:

• RJ45 Based
• 1000BaseT
• Gigabit-speeds with 10/100 compatibility
• Good for up to 100m Ethernet cables
• Work well in the same temperature range (0-70C)

This basically means that both formats are standard Gigabit Ethernet SFP ports that should work fine with any form of standard GbE cabling. Either one can be used without a problem by 99% of Cisco operators.

So, what’s the difference? Well, the only major difference between the two is that the SFP-GE-T conforms to NEBS Level 3 standards. Now it’s time to answer the obvious question you no doubt want to ask;

What is NEBS Level 3?

NEBS is short for Network Equipment Building System and it is a set of standards for building networking equipment that is able to withstand environmental stresses. In general, NEBS is only relevant for telecoms and high-level service providers. NEBS Level 3 regulates against many environmental stresses such as:

• Thermal margins
• Fire resistance
• Proper airflow
• Acoustic limits
• Vibration resistance (such as earthquakes)
• Failover capabilities
• RF tolerance and emissions
• Damage tolerance prior to failure

An NEBS Level 3 SFP transceiver is generally “Ruggedized-lite”. It is able to take on more stress without failing, and can be trusted to handle mission-critical applications without a problem. However, that also means that an NEBS-ready SFP-GE-T Cisco transceiver can be more expensive than the GLC-T option. Really, cost is the only difference that is worth mentioning.

Should I Choose an SFP-GE-T Transceiver Just to be on the Safe Side?

If we’re being honest then we’d have to say “probably not”. If you are going to deal with companies that require NEBS compliance – such as telecoms – they are likely going to tell you. Otherwise, the problems that NEBS will protect against are generally extreme cases.

If an earthquake was to hit your building, you’d probably have more important things worth worrying about than whether or not your SFP transceivers were still working. For just about every network, the Cisco GLC-T transceiver will be everything you need for a Gigabit Ethernet, and they are generally offered at a reduced cost.

If you are looking to save some money on your Cisco-compatible transceivers, then don’t forget that 1000 GIG has a range of SFP/SFP+ optical transceivers. These transceivers are all manufactured to the same standards as Cisco transceivers, and we provide ours with a lifetime warranty. 1000 GIG transceivers are completely 100% compatible, but they cost just a small fraction of the cost of a name-brand alternative.