BGP route Advertisement(

I have some question about how many routes(network prefix) should an AS learn or advertise.

<We can use BGP to advertise our address space to the ISPs but what are the ISPS going to advertise to our customer through BGP? There are a number of options:

They advertise only a default route.
They advertise a default route and a partial routing table.
They advertise the full Internet routing table.>

q1) How many network prefixes does an AS advertise ? I mean the prefixes made by IGP intra AS.
I guess it can be only one prefix if the AS has one aggregated network(supernet) such as
q2) Are there about 500,000 bgp prefixes(full routing table) in spite of supernetting ?
q3) Advertising method : ‘network’ command or Redistribute
a) Why we use Redistribute?
b) case study: OSPF table has 1,000 routes. Redistribute OSPF into BGP
I think this redisribution does not make sense because 1,000 routes is useless. These route should be aggregated and then advertised.


A post was merged into an existing topic: Introduction to BGP