Assuming you already have a spare rj45 to db9 dongle: Mini-USB(M) to RJ45(M), 8ft, Brocade Console Cable, + 9pin(F) to RJ45(F) adapter | eBay
If not just buy one as well (doesn't have to he brocade branded) RJ45 to RS232, DB9 9-Pin, Female to Female, CAT5/6, Brocade P/N 50-0000112-01 | eBay
If not just buy one as well (doesn't have to he brocade branded) RJ45 to RS232, DB9 9-Pin, Female to Female, CAT5/6, Brocade P/N 50-0000112-01 | eBay