CCNP Switching Exam Notes: Vlan And Vtp Configuration, Fast Ethernet, Ios Switch Commands


In a Cisco IOS command based switch, passwords are not case sensitive, whereas, in "set" command based switches, passwords are case sensitive.

12.0 VLANS

To configure a port, you need to open a terminal emulation program to the switch. Now, set the port speed and then the port duplex.

1. ISL: A Cisco proprietary trunking protocol, associated with Ethernet.. Supported by Catalyst switches and routers.
2. 802.1Q: This is an IEEE standard for the VLAN trunking protocols, associated with Ethernet. 
3. 802.10: A Cisco proprietary method for transporting VLAN information inside the standard 802.10 FDDI frames.
4. LANE : LANE stands for LAN Emulation and is associated with ATM. This is an IEEE standard for transporting frames over ATM networks.

Inter-Switch Link (ISL) is a Cisco proprietary VLAN trunking protocols, used for switched VLAN networks. ISL encapsulates the original Ethernet frame, and a VLAN-ID is inserted into the ISL header among several other fields.

By default, the management VLAN is assigned VLAN 1.

13.0 VTP:

VTP is a Layer 2 messaging protocol. It carries configuration information throughout a single domain. VTP operates in one of three modes:
1. Server mode: VTP Servers can create, modify, or delete VLANs and other configuration parameters for the specified VLAN domain.
2. Client mode: A VTP client can't create, change, or delete VLANs. 
3. Transparent mode : A VTP transparent mode is used when a switch is not required to participate in VTP, but only pass the information to other switches. Transparent switches don't work either as Server or clients.

Configurations made to a single switch, called VTP server, are propagated across the switch fabric under a single domain control. Other switches, configured as VTP clients, learn the configuration information from the server. It is important to know that, Cisco switches such as Catalyst 1900, acting as VTP servers save the VLAN configuration information in their Non volatile memory (NVRAM), whereas client keep the information only in running configuration.

A VTP advertisement necessarily consists of "Configuration revision number". Every time a VTP server updates its VLAN information, it increments the configuration revision number by one count. VTP clients, use the revision number to enforce the VLAN configuration Update.

There are two different VTP versions. VTP version 1 and VTP version 2. These versions are not interoperable. Version 1 is the default version. All switches in a given management domain should be configured in either version 1 or version 2. Some of the advantages of VTP version 2 are as below:
1. Token Ring support: Supports Token Ring LAN switching and VLANs. If Token Ring is used, this is the version required.
2. Version number auto propagation: In case that all switches are capable of running Version 2, only one switch need to be Version 2 enabled, Version number is automatically propagated to others.

14.0 Fast EtherChannel

The following are features of Fast EtherChannel that is running PAgP (Port Aggregation Protocol):
1. PAgP helps in the automatic creation of Fast EtherChannel.
2. PAgP does not group ports configured for dynamic VLANs. PAgP requires that all ports in a channel must belong to the same VLAN or should be configured as trunk ports.
3. PAgP does not group ports that work at different speeds or port duplexes.

15.0 Important IOS Switch commands:

The syntax for setting port speed on an IOS switch is:
speed { 10 | 100 | auto }
For setting the speed to 10mbps on module 1 port 5, the command is
speed 10
Similarly, to set the duplex mode on a switch:
duplex { auto | full | half}
For setting the duplex to half, use the command:
duplex half

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