Skip to main content

When to use VLSM

When to use VLSM

 1.1.3 It is important to design an address scheme that allows for growth and does not waste addresses. This page examines how VLSM can be used to prevent the waste of addresses on point-to-point links.
As shown in Figure , the network management team has decided to avoid the wasteful use of the /27 mask on the point-to-point links. The team applies VLSM to the address problem.
To apply VLSM to the address problem, the team breaks the Class C address into subnets of variable sizes. Large subnets are created for LANs. Very small subnets are created for WAN links and other special cases. A 30-bit mask is used to create subnets with only two valid host addresses. This is the best solution for the point-to-point connections. The team will take one of the three subnets they previously decided to assign to the WAN links, and subnet it again with a 30-bit mask.
In the example, the team has taken one of the last three subnets, subnet 6, and subnetted it again. This time the team uses a 30-bit mask. Figures and illustrate that after using VLSM, the team has eight ranges of addresses to be used for the point-to-point links.
The next page will teach students how to calculate subnets with VLSM.

Comments

Post a Comment

Popular posts from this blog

OSI layers / Peer-to-peer communications / TCP/IP model

OSI layers 2.3.4 This page discusses the seven layers of the OSI model. The OSI reference model is a framework that is used to understand how information travels throughout a network. The OSI reference model explains how packets travel through the various layers to another device on a network, even if the sender and destination have different types of network media. In the OSI reference model, there are seven numbered layers, each of which illustrates a particular network function. - Dividing the network into seven layers provides the following advantages: • It breaks network communication into smaller, more manageable parts. • It standardizes network components to allow multiple vendor development and support. • It allows different types of network hardware and software to communicate with each other. • It prevents changes in one layer from affecting other layers. • It divides network communication into smaller parts to make learning it easier to understand. In the foll...
Post a Comment
Read more

Advantages and disadvantages of link-state routing

Advantages and disadvantages of link-state routing 2.1.5  This page lists the advantages and disadvantages of link-state routing protocols. The following are advantages of link-state routing protocols:  Link-state protocols use cost metrics to choose paths through the network. The cost metric reflects the capacity of the links on those paths. Link-state protocols use triggered updates and LSA floods to immediately report changes in the network topology to all routers in the network. This leads to fast convergence times. Each router has a complete and synchronized picture of the network. Therefore, it is very difficult for routing loops to occur. Routers use the latest information to make the best routing decisions. The link-state database sizes can be minimized with careful network design. This leads to smaller Dijkstra calculations and faster convergence. Every router, at the very least, maps the topology of it...
Post a Comment
Read more

Symmetric and asymmetric switching / Memory buffering

Symmetric and asymmetric switching   4.2.8  This page will explain the difference between symmetric and asymmetric switching. LAN switching may be classified as symmetric or asymmetric based on the way in which bandwidth is allocated to the switch ports. A symmetric switch provides switched connections between ports with the same bandwidth. An asymmetric LAN switch provides switched connections between ports of unlike bandwidth, such as a combination of 10-Mbps and 100-Mbps ports. Asymmetric switching enables more bandwidth to be dedicated to the server switch port in order to prevent a bottleneck. This allows smoother traffic flows where multiple clients are communicating with a server at the same time. Memory buffering is required on an asymmetric switch. The use of buffers keeps the frames contiguous between different data rate ports. The next page will discuss memory buffers. Memory buffering   4.2.9  This page will explain what a memory buffer is...
Post a Comment
Read more