Is bit mask same as subnet mask?

[ZK]

Hi there,

I've done a lot of reading on IP addressing, and there are lot's of concepts floating around in my head, but I haven't quite grasped them completely. So I was wondering if any of you could answer the following 2 questions:

Q1) With reference to CIDR (Classless Inter-domain routing) Is the bit mask of a network(the mask used by routers to determine the network portion of an IP address) the same as the subnet mask of that network?

The way I see it, if a network is subnetted, it is using some bits of the host id portion of the IP address. So a bit mask uses only the bits to the left of the subnet id bits to determine the network id of the IP address. Then if the network IS subnetted, the LAN's own router uses an internal subnet mask (which will be longer than the bit mask) to see what subnet the IP address belongs to. Am I right in assuming this is how CIDR routing works?

Q2) How exactly does CIDR enable route aggregation?

Thanks a lot
ZK

 

[MasterRacker]

This should be posted in the TCP/IP forum.
Jeff
masterracker@hotmail.com

If everything seems to be going well: you don't have enough information.......

 

[DiscoDuane]

alls that the classless means is that the routers need to advertise the subnet mask along with the address. RIP will assume that default subnet masks are used because it doesnt send the subnet as well. So in order to route properly the Classless routers need the subnet mask

 

[ZK]

I'm not sure if you've answered my question(s) DiscoDuane.

ZK

 

[DiscoDuane]

q1) Yes
q2) not sure