Achievable throughput on shared, parallel 100BASE-TX downlinks

[imkilgour]

Hi all - I'm trying to estimate the potential throughput I will be able to achieve on a network we are building.

The core ring of the network will be composed of ruggedized industrial ethernet Cisco IE 3000-8TC-E, possibly each equipped with a IE 3000-8TM expansion module.  We will be using 1000BASE-BX SFPs on the IE-3000s to form a 1Gbps backbone on a single fiber.  The issue is that I want to establish branch connections out from each IE-3000 node on my ring to routers which can support 1Gbps, but I have no 1Gbps downlink ports available on my IE-3000's.  Therefore, I was thinking of paralleling as many 100BASE-TX copper links from the IE-3000 to my routers, so as to emulate a 1Gbps link and achieve maximum throughput.  Both sides will have 16x 100BASE-TX connections available... but what is the maximum number I can parallel together and what achievable real throughput can I assume given the innefficieny of paralleling multiple connections?

Any insight would be appreciated!

Thanks.

[Leo Laohoo]

You can form a maximum of of eight (8) links together to form an EtherChannel.  This maximum links is not a Cisco-defined standard but an IEEE standard.

[Joseph W. Doherty]

Disclaimer

The     Author of this posting offers the information contained within this     posting without consideration and with the reader's understanding  that    there's no implied or expressed suitability or fitness for any   purpose.   Information provided is for informational purposes only and   should not   be construed as rendering professional advice of any kind.   Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In     no event shall Author be liable for any damages whatsoever   (including,   without limitation, damages for loss of use, data or   profit) arising  out  of the use or inability to use the posting's   information even if  Author  has been advised of the possibility of  such  damage.

Posting

Some things to keep in mind.  Etherchannel of 8 100 Mbps links will provide 800 Mbps of aggregate bandwidth, but individual flows will only use 1 link and so be restricted to 100 Mbps.  Also, Etherchannel as it distributes flows across the links, depending on the hash and the flow attributes, it's possible some links will be busy while others are not.  In other words, Etherchannel won't behave exactly as a single clear link of 800 Mbps would.

Also, if your routers are software based, you'll need to look at the larger models to sustain 800 Mbps of throughput.

[imkilgour]

Thanks to both of you for your assistance!