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
I don't think that's how they intend for us to understand their half vs. full bandwidths.
Fabrics should be bi-directional, i.e. then can send and receive.
When Cisco first came out with duplex FastEthernet, they used to "advertise" bandwidth capacity as 200 Mbps, i.e. 2x the bandwidth of a half-duplex FE. In other words, this "new" duplex FE link, of 200 Mbps, was like two half duplex FE links of 100 Mbps.
Today, half duplex is becoming a rarity. Do we refer to FE links today as 200 Mbps or 100 Mbps, or gigE links today as 1 Gbps or 2 Gbps?
Besides full duplex becoming the norm, I think we often refer to bandwidth of links by their bandwidth from source to destination. For example, serial links are "full duplex", but we refer to a DS1/T1 as 1.5 Mbps, not 3 Mbps.
Fabric bandwidths, unlike link bandwidths, haven't really commonly settled how their two way bandwidth capacity is defined. Cisco describes their fabrics with two way bandwidths, Juniper seems to be trying to make this clear by providing half and full duplex for the same fabric/slot (although it may actually make it even more confusing).
Even Cisco isn't 100% consistent. If you research the bandwidth of a 6500's "classic bus", you'll mostly find it as 32 Gbps, but you'll find some references as 16 Gbps. I believe they're one in the same, but the former is the "duplex", bi-directional, bandwidth, and the latter is "half-duplex", or source to destination, bandwidth.
Original 3750 stack ring bandwidth is described as 32 Gbps, but I believe it's only 8 Gbps from source to destination (dual 8 Gbps full duplex stack ports.) Also, if you only have a stack with one ring port, Cisco describes the ring as half-duplex, and 16 Gbps. (On the 3750s, it's possible all ring traffic is unidirectional on one ring port at 16 Gbps, and so only if both stack ports are connected do you have bidirectional bandwidth. As the original 3750 10g model was noted it only supported 8 Gbps throughput, an ASIC [?] limitation, I suspect each stack ring ports is 8 Gbps, bidirectional.)
Hope the last two paragraphs haven't confused futher. What you might do is contact Juniper for clarification of their specifications.
