"brickwalls19" <>
???????: egroups.com...
> On May 23, 6:23 pm, "a" <a...@mail.com> wrote:
> > PC A|----------R1-------------------R2---------|-----PC B
> > Stage 1 Stage 2 Stage 3
> >
> > I just want to clear the basic concept.
> > For the data flow from PC A toward PC B, the source IP and destination
IP
> > are always keep the same no matter it is stage 1, stage 2 or stage 3.
Only
> > the source and dest MAC addresses will be changed. Am I right?
> >
> > Thanks
>
> It's a basic concept that is discussed in any "Networking for Dummies"
> book. Go home, turn off the computer, concentrate on what you read,
> and understand what you are reading.
>
> HTH
>
Why my concept is wrong?
The following is from
http://www.cisco.com/univercd/cc/td/...oc/routing.htm
Thanks
Switching algorithms is relatively simple; it is the same for most routing
protocols. In most cases, a host determines that it must send a packet to
another host. Having acquired a router's address by some means, the source
host sends a packet addressed specifically to
a router's physical (Media Access Control [MAC]-layer) address, this time
with the protocol (network layer) address of the destination host.
As it examines the packet's destination protocol address, the router
determines that it either knows or does not know how to forward the packet
to the next hop. If the router does not know how to forward the packet, it
typically drops the packet. If the router knows how to forward the packet,
however, it changes the destination physical address to that of the next hop
and transmits the packet.
The next hop may be the ultimate destination host. If not, the next hop is
usually another router, which executes the same switching decision process.
As the packet moves through the internetwork, its physical address changes,
but its protocol address remains constant, as illustrated in Figure 5-2.
Similar Threads
