🚀 go-pugleaf

>>   We would like to know the following: will IBM's TCP/IP for MVS use the same
>>   method as the CISCO router for transporting IP datagrams over X.25 virtual
>>   calls? In other words, will the scheme work, or is it necessary to have a
>>   mirror CISCO router at the mainframe end, connected to the mainframe in some
>>   other way?

I am not familiar with IBM's MVS TCP/IP implementation over X.25. If it
implements RFC877 then it will interoperate with the cisco X.25 just fine.
The only thing the IBM needs to do is place a call to the cisco's X.121
address with the first byte of Call User Data being 0xCC (hex CC). Then it
needs to send the IP datagrams over the virtual circuit in individual X.25
packets. That is for each IP packet, there should be one X.25 DATA packet.
For IP datagrams that are larger then the (possibly negotiated) X.25 packet
size, the IP datagram will be sliced up into multiple X.25 packet size
chunks and all but the last X.25 packet sent out with the M(ore)-bit set.

Greg Satz
cisco

PS. Questions about cisco products can be sent to
customer-service@cisco.com. We like mail.