ok, here is the scoop:
(sorry in advance for a long message..)
We support the following GBICs and cable lengths in current code...
SFP GBIC (1000BASE-SX or LX) with LC-type connectors. The GBIC can
use either:
– Longwave-length SFP GBICs (CSS5-GBIC-LX). The longwave length
transceiver (1000BASE-LX) can reach 550 meters for all multimode
media types. For single-mode fiber, the distance is 5,000 meters.
– Shortwave-length SFP GBICs (CSS5-GBIC-SX). The transceiver
distance can reach from 220 meters to 500 meters, depending on the
quality of the fiber.
We don't support the use of intermediate L2 devices as stated in this note...
Note You must connect the ISC ports directly to the two CSSs. You cannot use L2 devices on the ISC links between the two CSSs. Also, the ISC links must be dedicated to passing only ISC traffic.
There was a discussion on this and the following is a snip of it...
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We test with LX SFP to ensure that the CSS functions correctly with them installed. We do not test the CSS and LX SFP at a variety of distances. The SFP performance is unrelated to the operation of the CSS at the physical level; that testing is done by the SFP Vendor. If this SFP is the Cisco 1000Base-LX/LH SFP, then the online documentation certainly states that with the correct fiber 10KM is possible even though the .z standard only supports 5KM. Link below: http://www.cisco.com/en/US/products/hw/modules/ps5000/ps5249/
The 33 microsecond link latency at 10KM should not, in my opinion, impact ASR operation. This is an opinion, we have not tested this configuration.
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That being said, Cisco officially supports the lengths stated in the documentation referenced at the beginning of the message. Realistically, it is just layer 1 at some point and should not matter. The fact that we cannot support an intermediate L2 device between them seems to be the most limiting factor (to me at least).
Hope that helps...
-Steve
