The latest documentation says that trunking over long distance is supported. See http://www.brocade.com/downloads/documents/data_sheets/product_data_sheets/isl-trunking-ds.pdf
When checking the lastest FOS 7.x docu there is a table (see attached table from FabricOS 7.2 Admin guide, page 576) which indicates that only one 2-port 2Gb trunk per switch is supported in LD mode at 200km. The number of 4Gb trunk ports at 200km is 0.
The good old "Designing Next Generation 4Gb Brocade SANs" guide has a table that states that 125km is supported for a 2x4Gbit LD trunk.
1. is the old design doc still valid, an can we use trunking up to 125km with 2x 4Gb links?
2. what are the current limits for 8Gb and 16Gb long distance fabrics?