1.6 Dual Gigabit Ethernet

Posted by JTSF at Sunday, June 02, 2013 Read our previous post

Although the motherboard which I purchased does not come with two Gigabit Ethernet ports, there is always an option to upgrade to this feature by simply adding another network interface card (NIC). There are several ways to utilize two Ethernet ports, you can read about all the methods here.

Most commonly, we have two kinds of deployments:

1. Active - Standby

• 1 link in Active mode; transmitting data.
• The other link in passive Standby mode.
• When the active link goes down, the standby link detects the failure and takes over the active role.
• Enhance connectivity resiliency but throughput remains at 1Gb.

2. Link Aggregation / Etherchannel

• Two physical links are bundled together; In Cisco terms, it is known as Etherchannel or Port-channel.
• Logically, it is viewed as 1 link.
• Both ports transmit data concurrently.
• Enhance connection resiliency and increase throughput to 2Gb.

Deployment 2 is certainly preferred. I am sure you wouldn't employ two workers, allowing one to sleep the whole day while the other one works like a slave.


Link Aggregation (LAG) Requirement
It gets a little tricky to deploy Link Aggregation (LAG) at home. You will need to configure both the NAS and the Switch to form the bundled link. Take note of the requirements you need:

1. Two Gigabit Ethernet ports (preferably of the same chipset) available on the motherboard.
2. The NAS OS needs to support IEEE802.3ad Link Aggregation protocol (LAG).
3. You own a managed Switch and it also supports LAG.

Benefits of Link Aggregation
This is subjective to the setup and usage of the NAS in your home. I would like to highlight a few points here:

• LAG provides link redundancy. The avaliability of the NAS is enhanced whereby you can afford 1 cable or 1 NIC failure.
• LAG is only useful when you have multiple clients reading / writing files to your NAS simultaneously. You will only receive a performance boost during concurrent sessions.
• LAG does not improve 1-to-1 connection. The transfer speed of one connection towards your NAS will not exceed the speed of one network port, which is 1Gb in our scenario.

To sum it up, LAG is more practical in Enterprise and Corporate environments. It is commonly deployed on a Server that has many clients accessing it simultaneously and for redundancy if one of the NICs fails.

Understanding How LAG Works
If you wish to read all about LAG, refer to here which discuss about Link Aggregation and LACP basics.

Else, read on and I'll explain in layman terms.

              *In normal scenario, the desktop connection is usually a 1Gb and will be the bottleneck.

Conclusion
As illustrated above, Link Aggregation (LAG) works on a flow base concept. It is only beneficial when you have multiple simultaneous connections. In reality, a single wired desktop will never exceed speed of 1Gb unless the desktop also runs LAG or has a 10Gb connection. Look around your own environment and assess how practical it is to deploy LAG. For my setup, I'll keep this option open and will explore further.