From: jmfres11@ucs.usl.edu (Karthikeyan Gurnswamy)
Newsgroups: bit.listserv.novell
Subject: Re: IPX Atrocities?
Date: 23 Nov 92 20:56:24 GMT
Organization: Univ. of Southwestern La., Lafayette

In article <9211202137.AA17640@dny.rockwell.com> Novell LAN Interest Group <NOVELL@SUVM.BITNET> writes:
>I am working on a project for NASA to identify the operational issues
>of the IPX/SPX protocol.  NASA wishes to remove IPX, and a number of
>other protocols, from their WAN.  This desire stems mainly from the negative
>image most network engineers with NASA (and many other large organizations)
>have of the IPX protocol.
>
>The following are a sample of the negative  responses I have encountered
>to the IPX potocol:
>
>1. The ping-pong effect of the IPX protocol.
Do you mean acknowledgment packets with IPX ? Its never there ! IPX is just
like any protocol.

>2. IPX is half duplex
That's not true. If you are talking about piggybacking of acknowledgement
packets like HDLC, that's not there in IP too ..

>3. Excessive SAPing of network devices
SAP has hidden advantages especially when you want instant access to a 
network resource. SAPs make sure that your nearest server knows where all
the distant resources lie. If you are using TCP/IP and name servers then
it takes time to resolve a particular site and its resources. If you are
using good routers then you can reduce the total network congestion created
by SAP because they do not propogate SAP broadcasts as such.

>4. Underscores in server names conflict with X.400 gateways.     
That's got nothing to do with IPX because it is just a protocol that carries
info. for a destination and Novell happen to use it. Well you got to blame
the Novell's design for the gap. What X.400 gateway are you using ?      

>5. Small packet sizes are inefficient
Longer packets are subject to higher error rates compared to short packets. 
Higher error rates leads to retransmission at some point and low throughput.
Moreover longer packets demand a higher memory requirement (speaking 
theoritically ) of buffers and you may have a problem routing it where
you have small MTU limitation - then you would have to fragment it and
send it - messy.  ** MTU - Maximum transmission unit.

>6. Packet Burst does not have dynamic congestion control for sliding window
This is very true. But this issue depends on what kind of WAN and setup you
are using. Sliding window is theoritcally advantageous and that greatly
depends on the WAN link error characteristics. 

>7. IPX is difficult to manage as a protocol
IPX is based on Xerox Corp's XNS and it is more than a packet with headers.
That is just the tip of a big networking iceberg. The whole idea is connecting
a variety of resources on an internetwork. So if you are thinking that Novell
should change to TCP/IP (I doubt) you may have some serious drawbacks in the
future and miss the speed to access your resources. One basic thing is the
memory requirement on a DOS workstation for a particular protocol used. IPX
is kindof cute that way. A TCP/IP stack would take atleast thrice the size
of IPX ...

>
>Many of these arguments are unfounded.  I am in the process of researching
>answers/solutions to these concerns.
>
>If any of you have experienced similar resistance to IPX please let me
>know the arguements for and against.  I am NOT looking for bugs in
>NetWare such as phantom servers on very large SLISTs. Just issues.
>
>Novell has offered their assistance with the project and the
>final product will be available to any of those who wish it.
>
>
>Brad hall

Karthik
/----------------------------------------\--------------------------\
| Karthikeyan Guruswamy                  |                          |
| Graduate Student, Computer Science     | Why does'nt my:          |
| Center for Advanced Computer Studies   |                          | 
| Univ. of SouthWestern Louisiana        |    NET WORK ?            |
| Lafayette, LA 70501                    |                          |
| Email: jmfres11@ucs.usl.edu            |                          |
|                                        \--------------------------\
| The opinions stated are solely mine and does not reflect the views|
| of anyone in my organization ...                                  |
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