Network Simulator for Cisco CCENT

Network Simulator for CCENT has the following features:
1. Lab exercises for hands-on practice.
2. Router and switch simulator
3. Simulate Cisco® IOS routers (2501/2503) or switches (2950).
4. Support for 200+ router and switch commands
5. Labs for 1900 and 2950 switches included
6. Detailed help files
7. Network designer that provides drag and drop feature for inserting devices and connectors.
8. GUI vased device configurator.
9. Support short form commands. You can type short form commands in IOS simulator for router/switch commands just like in actual router/switch.

Download at Cisco CCENT Simulator
Visit Network Simulator home page

VLAN Types

1. Native VLAN: It's a VLAN that is not tagged when used on dot1q trunk. Frames using native VLAN traverse without any tagging. Workstations and some switches do not understand dot1q, and only work with frames without tag (Native VLAN).

2. Default VLAN: It's typically VLAN 1 (At least on Cisco switches) - Vlan that is assigned to the switch port, when u get switch "out of box". You can change the default VLAN to any other specific VLAN by using "native vlan" command on Cisco swiches.

3. Static VLAN: "Static VLAN membership is perhaps the most widely used method because of the relatively small administration overhead and security it provides. With Static VLANs, the administrator will assign each port of the switch to one VLAN. Once this is complete, they can simply connect each device or workstation to the appropriate port." The other method is 4.

4.Dynamic VLAN: Static VLANs are the most common form of port VLAN assignments. It is possible to have the switch dynamically choose a VLAN based on the MAC address of the device connected to a port. For dynamic VLAN assignment, you need a VTP database file, a VTP server, a VTP client switch, and a dynamic port. After you have properly configured these components, a dynamic port can choose the VLAN based on whichever device is connected to that port.

5. Access VLAN: There are two modes of a switch port, Access and Trunk: Access switchport mode is used to connect to the end devices, and trunk switchport mode is typically used to interconnect two switches (or a router and a switch). So Access VLAN is the vlan which is assigned to port that is in ACCESS mode and connected to the end device

Tidbits - IP Helper Address

The Internet is based on client/server model. For example, a host may need to contact a DHCP (Short for Dynamic Host Configuration Protocol) server for obtaining its IP address. The requests are usually sent as broardcast messages. Since routers do not forward broadcasts, the DHCP server must be located in the same subnet as that of the client requesting the service. But, practical reasons may prohibit a DHCP server to be placed on each subnet of a network. One workaround to this problem is IP helper address. A router, configured with IP helper address can unicast the broadcast message received from a client (or host) in one subnet to a given IP address (of the server) in another subnet, which in turn provides the DHCP information to the client computer.
IP helper addresses can also be used for any other requests such as DNS requests or to locate TFTP servers on a network. IP helper address enables a network administrator to centralize the server services, such as DHCP service or DNS service.

Few CCNA Questions ...

What is true about VLAN trunk protocol?

a. VTP is statically configured, but no built-in intelligence is available.
b. VTP provides intelligence to configure switches across the network
c. VTP is not designed to distribute information across the switch fabric
d. None of the above

ans: b

VLAN Trunk Protocol (VTP) is a layer 2 protocol that maintains VLAN configurations through a common administrative domain. Configurations are made to a VTP server, and are propagated
across trunk lines to all switches in the VTP domain. VTP provides auto-intelligence for configuring switches across the network.