[AusNOG] LR to LRL

[Lincoln Dale]

On Wed, Jul 8, 2015 at 12:13 AM, Skeeve Stevens <
skeeve+ausnog at eintellegonetworks.com> wrote:

> Just wondering if anyone know of risks of using an LR (10km) optic to an
> LRL (1km) optic are...   will they work fine, or will the LR burn out the
> LRL.
>

The answer to this question is: "it depends".

Clueful vendors that sell optics like LRL do so in a way that accepted RX
power levels are a superset of the TX power levels.

You don't mention 1G/10G/40G/100G, I think your're asking about 10G but
I'll include 40G & 100G too.

Per
http://www.arista.com/assets/data/pdf/Datasheets/Transceiver-Data-Sheet.pdf:

10G SFP+:
 - 10GBASE-LR TX power: -8.2 to 0.5 dBm, RX power: -14.4 to 0.5 dBm, max
10km
 - 10GBASE-LRL TX power: -8.2 to 0.5 dBm, RX power: -12.5 to 0.5 dBm, max
1km

40G QSFP+
 - 40GBASE-LR4 TX power: -7 to 2.3 dBm, RX power: -13.7 to 2.3 dBm, max 10km
 - 40GBASE-LRL4 TX power: -7 to 2.3 dBm, RX power: -13.7 to 2.3 dBm, max 1km
 - 40GBASE-UNIV TX power: -7 to 3.5 dBm, RX power: -10 to 3.5 dBm, max 2km

100G QSFP100:
 - 100GBASE-LR4 TX power: -4.3 to 4.5 dBm, RX power: -10.6 to 4.5 dBm, max
10km
 - 100GBASE-LRL4 TX power: -6 to 4.5 dBm, RX power: -10 to 4.5 dBm, max 2km


LRL is an interesting one, as its an example of the failure of standards
bodies (IEEE) to create a standard around something that the industry
(customers) wanted. So clueful vendors (switch, router, optics vendors)
went and created it anyway.
Optically LRL is the same as LR but with a cost-reduced receiver.

The 40G-UNIV I list above is even more interesting. There is no such thing
as a 40G optic that can operate on both SMF and MMF but its technically
possible, and we enabled it: a transceiver that is 'optically' 40GBASE-LR4
but can operate over a pair of fibers of either multimode (OM3/OM4 150m) or
single mode fiber (500m) where the other side can be standards-based
40GBASE-LR4.


Net-net, the answer is "it depends" but clueful vendors do the right thing.
Even more clueful vendors (I'm probably biased here) innovate and solve
pain points around investment protection of fiber plant.


cheers,

lincoln.
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