darren@shapec.mdcbbs.com0 (09/01/90)
I have a configuration query, relating to VAX-PSI, Cisco Router and X.25 I currently have a VAX, with a PSI Connection onto the X25 Network (PSS). This is used to bring up DECnet Connections. Going through Public Networks is becoming a little slow, for what I wish to do, so therefore I am considering leased lines. Current: 9.6 x25 ----------------------|VAX with PSI Software| Can I do this? : (LAN) 9.6 x25 (Public-PSS) | ----------------------|Cisco| | | |--|---|VAX with PSI Software| |AGS2 | | ----------------------| | | 64k Leased Line What this would give me (if possible), is high speed DECNet over 64k line, plus backup of PSS Public Line. However, there is now no direct physical connection from VAX to x25 - Is it possible for the CISCO to complete a virtual circuit? (to give me logically what I have currently). Or do I have to keep my PSI Connection, direct into the VAX? Help Appreciated. Darren Bolland Shape Data Ltd Cambridge England 44 223 316673
forster@cisco.com (Jim Forster) (09/04/90)
Darren, The answer to your question is "It depends". It depends on what services you are using VAX PSI for. My understanding is that VAX PSI provides X.25 access for at least 3 purposes: 1) Forwarding DECNet Phase IV datagrams over VC's, 2) Allowing Triple-X (X.29/X.28/X.3) based login to the vax from PAD's 3) allowing application programs to open X.25 VC's to arbitrary hosts & services through a library interface. If the machine(s) at the other end of PSS are DEC Vaxes, then you could leave the PSS line directly connected to your vax, and still use the 64k leased line through the Ethernet & cisco as your primary path. 9.6 x25 (Public-PSS) --------------------------------------------- | (LAN) | | | |Cisco| | ----------------------- | |--|---|VAX with PSI Software| |AGS2 | | ----------------------- ----------------------| | | 64k Leased Line If the machines at the other end of PSS are also cisco routers, then you can do what you pictured: (LAN) 9.6 x25 (Public-PSS) | ----------------------|Cisco| | | |--|---|VAX with PSI Software| |AGS2 | | ----------------------| | | 64k Leased Line We don't support application #3, VAX library access to X.25 via Ethernet. If you are also using VAX PSI also to allow Triple-X access to the VAX (application #2 above), then can use another cisco product, the Protocol Translator, to convert from the Triple-X protocols to LAT. Feel free to call or write to us (customer-service@cisco.com) for more details. -- Jim Forster cisco Systems
satz@cisco.com (Greg Satz) (09/04/90)
>> 9.6 x25 (Public-PSS) | >> ----------------------|Cisco| | >> | |--|---|VAX with PSI Software| >> |AGS2 | | >> ----------------------| | | >> 64k Leased Line Yes, the cisco software can be made to do this but it requires the following changes to your topology. LAN 9.6 x25 (Public-PSS) | ----------------------|Cisco| | | | |--|---|VAX with PSI Software| |AGS2 | | | ----------------------| |______| 64k Leased Line X.25 This solution utilizes the X.25 switching functionality to switch PSI calls from the PSS through the cisco and into the VAX. It also requires that the Vax act as a router from its X.25 interface to its ethernet. Incoming Call Requests will be forwarded from the cisco to the Vax. The Vax will extract the DECNET packets from the established VC and forwarded it back to the cisco for further forwarding down the 64K leased line. This requires that you get an extra serial interface running X.25 to connect up the Vax. The drawback to this is the extra serial interface and the extra hop across the serial interface and ethernet. The extra hop can be overlooked if you are using 9.6 serial X.25 lines on the PSS as this is slow enough that the extra two hops won't be noticed. This also assumes you can control the demands on the Vax system resources. The advantage is that this solution will work in today's shipping software. Greg Satz cisco