How does internet routing work?

[b***@hotmail.com]

If I send a packet to <IP address>, how does the router know where to send it to? I saw on a video on the net, where Vint Cerf *himself* said that an IP address has <some bits> reserved for country, then city, and so on.... is that true? ...makes it sound kind of like a PHONE no...? :)

(I've already read a book on networks, but this was not explained....)


Thanks.

[Jorgen Grahn]

Post by b***@hotmail.com
If I send a packet to <IP address>, how does the router

Which router?

Post by b***@hotmail.com
know where to send it to?

It has a routing table which answers "which of my neighboring nodes
should I send this packet to, to get it /closer to/ its destination?"

Home routers tend to have a simple, handmade routing table.
Routers out on the net learn from each other, using elaborate
schemes I know little about.

Post by b***@hotmail.com
I saw on a video on the net, where Vint Cerf
*himself* said that an IP address has <some bits> reserved for
country, then city, and so on.... is that true?

No.

/Jorgen

[Les Cargill]

Post by b***@hotmail.com
If I send a packet to <IP address>, how does the router know where to
send it to? I saw on a video on the net, where Vint Cerf *himself*
said that an IP address has <some bits> reserved for country, then
city, and so on.... is that true? ...makes it sound kind of like a
PHONE no...? :)
(I've already read a book on networks, but this was not
explained....)
Thanks.

1) There is the usual, netmask-based routing yuou're likely to see in
a residence.

2) There are more sophisticated protocols for rules or
learning at layer three. One such is OSPF.

Effectively, what a router needs to understand is "Given this PDU, which
port to I send it on?". The answer may be "no port at all."

Technically, a canonical router has only two ports.