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- Newsgroups: comp.protocols.ibm
- Path: sparky!uunet!wupost!rice!dboyes
- From: dboyes@is.rice.edu (David E Boyes)
- Subject: Re: TCP/IP impact on a S/3090 M/F
- Message-ID: <1992Jul24.021550.16519@rice.edu>
- Sender: news@rice.edu (News)
- Organization: Rice University
- References: <1992Jul23.160241.23996@inesc.pt>
- Date: Fri, 24 Jul 1992 02:15:50 GMT
- Lines: 67
-
- In article <1992Jul23.160241.23996@inesc.pt> prc@rabbit (Pedro Ramalho Carlos) writes:
-
- > 1-Will I loose much performance by installing TCP/IP at all - even
- > with no sessions (due to daemons, etc.) ?
-
- It's another set of started tasks, so it will lose you some
- performance due to working set and real memory residence.
- Fortunately, MVS does memory management and paging/swapping
- management pretty well, so if your system is reasonably well
- tuned to begin with, you shouldn't see a significant impact.
-
- > 2-What is the relative load on the host of a tn3270 session compared
- > with a native 3270 session?
-
- About half again as much as a SNA-based user, as a rough
- guideline. With an SNA user, the device controllers are handling
- a significant amount of the I/O interrupts, which reduces the
- interruptions to the access method and OS. Most of the MVS
- implementations I've worked with of TCP essentially serve to
- connect a TCP connection to a VTAM LU and then MVS manages it as
- a SNA connected user. I have less of an estimate on non-terminal
- functions such as FTP.
-
- The difference is very similar to driving a non-SNA terminal, but
- not quite as resource hungry.
-
- > 3-And what is the relative performance from the user standpoint?
-
- Depends a lot on network load and CPU load. There is more host
- processing involved in the TCP connection, but on a lightly
- loaded network and moderatly loaded host, I wouldn't expect a
- significant difference. It's comparable to a cross-domain VTAM
- connection between two hosts connected by a real CTC.
-
- > 4-Will I need to upgrade the mainframe with CPU or RAM?
-
- Never hurts. 8-) More main storage might be useful if you're
- heavily overcomitted on storage, but that's no different than any
- other major application subsystem. The answer to this question
- really depends on just how heavily loaded your current system is
- and how much more load it can tolerate without some significant
- (measured on your own scale) performance degradation.
-
- > 5-If I use IBM's own TCP/IP will I get the same kind of support from
- > them?
-
- The IBM TCP/IP group is one of the most vocal and externally
- visible groups of IBM developers I know of. They listen, they
- propose, and they're willing to fix things if the general
- consensus of the net is that they're going the wrong direction.
- IBM is still heavily committed to SNA, and they'll still be a lot
- less confused if you stick to SNA, but TCP support is pretty
- good.
-
- As a side note, most heavy MVS sites I'm aware of use IBM's TCPIP
- software, but purchase the hardware interfaces from other
- vendors, such as Bus-Tech, Interlink, or OpenConnect Systems.
- Some use a device from McData that appears to the host as an
- local SNA 3174, but accepts network connections instead of CUT
- terminals.
-
- >--pedro ramalho carlos (prc@inesc.pt)
-
-
- --
- David Boyes
- dboyes@rice.edu
-