Alright my friend... VLSM (Variable Length Subnet Mask) -- This does exactly what it says it does -- It gives us variable length subnet masks that we can use with our routing protocols. The concept of classes is completely out the window with VLSM. My IGPs can send routes with variable length subnet masks, and we use this for subnetting. For instance 192.168.0.0/24 can now be broken down into 192.168.0.0/25 and 192.168.0.128/25.
CIDR (Classless Interdomain Routing) -- This is basically applying the concept of VLSM but at the ISP level. Before CIDR the internet was a classful place. We hav Class A, Class B and Class C addresses, and everything had to be allocated based on those terms. If you wanted 1000 addresses you probably got 4x class C address blocks. The internet routing table consisted of /8 /16 and /24 netblocks. With CIDR, we can have the concept of variable length subnet masks in our routes as well. CIDR is often thought of as "supernetting" Summarization -- This is simply an aggregation technique. We can summarize many routes into a single route. For instance instead of advertising 192.168.0.0/24 - 192.168.7.0/24 we can advertise it as one summarized route , 192.168.0.0/21. Summarization allows us to keep routing tables smaller. In this example we'd have a single /21 summary route instead of 8 individual /24 routes in the routing table Subnetting -- This is the process of taking a network and breaking it down into smaller pieces. For instance, again say we were allocated teh 192.168.0.0/21 addrress block. We could subnet that address down into 8 individual /24 networks Supernetting -- The opposite of subnetting. This is aggregating many individual subnets into a larger block, similar to summarization HTH 2009/10/22 ρ♥Я♥д♥Ð♥ΐ♥ρ♥ ρ <[email protected]> > Dear Team, > > could u plz explanin me about CIDR,VLSM,Summerization,subnet and > supernetting briefly. it is very urgent for me.. > please do on priority which would help me to make good career... > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > -- Regards, Joe Astorino CCIE #24347 (R&S) Sr. Technical Instructor - IPexpert Mailto: [email protected] Telephone: +1.810.326.1444 Live Assistance, Please visit: www.ipexpert.com/chat eFax: +1.810.454.0130 IPexpert is a premier provider of Classroom and Self-Study Cisco CCNA (R&S, Voice & Security), CCNP, CCVP, CCSP and CCIE (R&S, Voice, Security & Service Provider) Certification Training with locations throughout the United States, Europe and Australia. Be sure to check out our online communities at www.ipexpert.com/communities and our public website at www.ipexpert.com
_______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
