Hi,

I've been trying to read up on PPP and have got myself into a confused
mess. Most of the information that I've gathered is from Wikipedia.

So here goes...
 
# From Wikipedia: "The Point-to-Point Protocol, or PPP, is commonly
used to establish a direct connection between two nodes"

Suppose I'm using a dialup line. The modem 'dials into' my ISP's
server and establishes a connection. Effectively, isn't this a
one-to-one direct connection? Can't I have a simple script which does
the following as soon as the modem has 'dialled into' the ISP's
server:

1. Change my machine's IP addresss to a pre-determined IP address
(probably provided by the ISP when I purchased the net connection)
2. Change the routing rules to route all outgoing network traffic
through a pre-determined IP address (the IP address of the server
which I've just dialled into)
3. And finally, change /etc/resolv.conf

As soon as the modem disconnects, another script could bring all the
network configuration back to the original state.


# From Wikipedia: "PPP was designed to work with several network layer
protocols, such as IP, IPX and AppleTalk..."

As per my understanding, PPP is simply a 'wrapper' protocol. Given two
nodes connected to each other using a single link (cable, connection
media, whatever), PPP may be used for communicating using multiple
protocols at the same time. i.e., under normal circumstances, only one
of IP or IPX may be used, at any given time. However, by using PPP,
both IP and IPX, can be multiplexed.

 
# From Wikipedia: "PPPoE, point-to-point protocol over Ethernet, is a
network protocol for encapsulating PPP frames in Ethernet frames."

If I understand this correctly, Ethernet works a layer below PPP. Why
would PPP frames be encapsulated in Ethernet frames? Shouldn't it be
the exact opposite? Additionally, since PPP encapsulates IP, IPX,
etc., out of which (at least) IP datagrams can be sent 'inside'
Ethernet frames (the way a 'normal' LAN work), why would anyone want
to use PPPoE?
 
Any answers to these questions? Or pointers to where I can read up
stuff written in plain English?
 
Nandz.
-- 
http://nandz.blogspot.com
http://foodieforlife.blogspot.com

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