In the olden days I referred to, we utilized two entirely disparate technologies (although companies eventually conjoined in an arranged marriage) for ESCON channel extension:
- NSC: a half-software, half-outbound-hardware solution - CNT: a 100% outbound-hardware solution Each product could convert a mainframe I/O at site A into a bundle of TP packets, transmit them to site B, and reconstruct them so that they appeared to the recipient as a locally generated I/O. Each product, in its own disparate way, allowed for the definition of a switch at site B, effectively providing doubly switched I/O: the first one managed at A by MVS, the second managed at B by the channel extender. When we first began to convert to FICON over DWDM, cascading was still a gleam in the eye of its architects. The mechanism for two switches was built into the I/O protocol, but gismos required to implement cascading were not yet on the market. So we struggled along for a while with more DWDM links than we wanted until the new switches became available. Now both switches are defined natively in the IODF. We have computers and peripherals both sites. Everything talks together as if there were a single glass house. As I've said before in this forum, ESCON is an absolute disaster over DWDM at 100 KM. That's why FICON was brought in--even a little ahead of its time. Rick Fochtman <[EMAIL PROTECTED]> Sent by: IBM Mainframe Discussion List <[email protected]> 02/01/2007 06:20 PM Please respond to IBM Mainframe Discussion List <[email protected]> To [email protected] cc Subject Re: Cascaded FICON and HCD ----------------------------<snip>--------------------------- The short answer is Yes, you can do it. FICON is so fast that you should not have trouble with 12 drives--assuming that distance is not a problem. I don't know what the native limitations are, but we use DWDM to 120 KM. Actually in the 'olden days' of ESCON, channel extender products provided a similar capability, but the pathing was not known to MVS. FICON lets it all hang out. --------------------------<unsnip>-------------------------- Pardon me; my education is lacking. DWDM ?? "Dark fiber" ?? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
