Re: LAN - IPX/SPX and TCP/IP

Karthik Balaguru <(E-Mail Removed)> 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/Interne...acket_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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Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
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