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From: Karthik Balaguru on 1 Mar 2010 06:42
Hi,
I understand that IPX and SPX both provide
connection services similar to TCP/IP.
Here, IPX is similar to IP and SPX is similar
to TCP and hence eager to know about this.

1. How does the performance of IPX/SPX
exceed that of TCP in LAN and what are
the main design factors that enabled
IPX/SPX to perform better than TCP in
case of LAN ?
2. Why is IPX/SPX not used in LAN alone
if its performance is superior to that of
TCP in the case of LAN ?

I searched the internet and landed up in
few links but it did not seem to convey
some clear reasons for this -
http://en.wikipedia.org/wiki/IPX/SPX .
Any ideas ?

I have included the linux and windows
networking groups to get to know the
various thougths regarding this.

Thx in advans,
Karthik Balaguru
From: Tomi Holger Engdahl on 2 Mar 2010 08:41
Karthik Balaguru <karthikbalaguru79(a)gmail.com> writes:

> Hi,
> I understand that IPX and SPX both provide
> connection services similar to TCP/IP.
> Here, IPX is similar to IP and SPX is similar
> to TCP and hence eager to know about this.
>
> 1. How does the performance of IPX/SPX
> exceed that of TCP in LAN and what are
> the main design factors that enabled
> IPX/SPX to perform better than TCP in
> case of LAN ?

As the node address is usually identical to the MAC address of the
network adapter, the Address Resolution Protocol is not needed.
For routing, the entries in the IPX routing table are similar to IP
routing tables; routing is done by network address.
IPX can be transmitted over Ethernet using several encapsulation
types. It seems that most (maybe all) encapsulation types
rely on the ethernet level data checksums only (ethernet card
hardware does).

In TCP/P networking in Ethernet in every packet there would be
to sets of checksums in every packet, because both IP and
Ethernet layers have their own checksums that needs to be added
when sending packet and checked when receiving. This could
be the one reason for better perfomance: less processing
needed for data checksums handling.

> 2. Why is IPX/SPX not used in LAN alone
> if its performance is superior to that of
> TCP in the case of LAN ?

When the processing power of the PCs increased, the situation
became soon so that there was no practical difference on the
performance of those system..
The issues were more processing power on PC CPUs,
better optimized TCP/IP stacks taken to use and
cheaper software (TCP/IP software used to be first expensive extra
software, then soon it became as standard feature in Windows also).

When TCP/IP was more widely supported and had many features
better than IPX, it became more widely used. I have worked
at IT department of one international company and seen things
tranforming from IPX networking (and several other legacy
technologies) to TCP/IP networking.

> I searched the internet and landed up in
> few links but it did not seem to convey
> some clear reasons for this -
> http://en.wikipedia.org/wiki/IPX/SPX .
> Any ideas ?

Read also
http://en.wikipedia.org/wiki/Internetwork_Packet_Exchange

> I have included the linux and windows
> networking groups to get to know the
> various thougths regarding this.
>
> Thx in advans,
> Karthik Balaguru

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/
From: Karthik Balaguru on 2 Mar 2010 12:21
On Mar 2, 6:41 pm, Tomi Holger Engdahl <t...(a)suola.niksula.hut.fi>
wrote:
> Karthik Balaguru <karthikbalagur...(a)gmail.com> writes:
> > Hi,
> > I understand that IPX and SPX both provide
> > connection services similar to TCP/IP.
> > Here, IPX is similar to IP and SPX is similar
> > to TCP and hence eager to know about this.
>
> > 1. How does the performance of IPX/SPX
> > exceed that of TCP in LAN and what are
> > the main design factors that enabled
> > IPX/SPX to perform better than TCP in
> > case of LAN ?
>
> As the node address is usually identical to the MAC address of the
> network adapter, the Address Resolution Protocol is not needed.

Interesting to note that ARP was not needed :-)

> For routing, the entries in the IPX routing table are similar to IP
> routing tables; routing is done by network address.
> IPX can be transmitted over Ethernet using several encapsulation
> types. It seems that most (maybe all) encapsulation types
> rely on the ethernet level data checksums only (ethernet card
> hardware does).
>

So, in IPX, there is only level of checksum and that too at
the ethernet level only. I think this would bring in some
difference.

> In TCP/P networking in Ethernet in every packet there would be
> to sets of checksums in every packet, because both IP and
> Ethernet layers have their own checksums that needs to be added
> when sending packet and checked when receiving. This could
> be the one reason for better perfomance: less processing
> needed for data checksums handling.    
>

Appears True !

> > 2. Why is IPX/SPX not used in LAN alone
> > if its performance is superior to that of
> > TCP in the case of LAN ?
>
> When the processing power of the PCs increased, the situation
> became soon so that there was no practical difference on the
> performance of those system..
> The issues were more processing power on PC CPUs,

I think, even though the processing power of PC CPUs
doubles/triples, if the protocol is robust, it would be able to
survive the competition from other similar protocols.
Considering the initial performance advantages of IPX/SPX ,
i think it should have survived against TCP/IP. I wonder
how it lost against the TCP/IP !

> better optimized TCP/IP stacks taken to use and
> cheaper software (TCP/IP software used to be first expensive extra
> software,

:-) :-)
Interesting to know that IPX/SPX was coslier than
TCP/IP stacks ! Any idea of the cost price ? :-)

> then soon it became as standard feature in Windows also).
>

I think, TCP/IP stack distribution along with Windows seems
to be a good promotion factor for TCP/IP . But, i wonder why
Windows did not opt for IPX/SPX as it was very much good
interms of performance compared to TCP/IP initially ?

> When TCP/IP was more widely supported and had many features
> better than IPX, it became more widely used.

Can you share the major features that were incorporated later
in TCP/IP that inturn paved way for the dominance of TCP/IP
over IPX/SPX ?

> I have worked
> at IT department of one international company and seen things
> tranforming from IPX networking (and several other legacy
> technologies) to TCP/IP networking.
>

Great !
Hope to hear lot of interesting stuffs regarding this IPX
networking to TCP/IP networking from you :-)

I also wonder whether it is only due to technical reasons,
IPX/SPX lost to TCP/IP. Any thoughts ?

> > I searched the internet and landed up in
> > few links but it did not seem to convey
> > some clear reasons for this -
> >http://en.wikipedia.org/wiki/IPX/SPX.
> > Any ideas ?
>
> Read also http://en.wikipedia.org/wiki/Internetwork_Packet_Exchange
>
> > I have included the linux and windows
> > networking groups to get to know the
> > various thougths regarding this.
>

Thx in advans,
Karthik Balaguru
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