RSSAll Entries in the "VLAN/VTP" Category

How to reset VLAN Trunking Protocol (VTP) Revision Number on Cisco Switches

VLAN Trunk Protocol (VTP) reduces administration in a switched network and this will reduces the need to configure the same VLAN everywhere. When you configure a new VLAN on one VTP server, configuration revision number will increase by one and the VLAN is distributed through all switches in the domain. VTP revision number is a very crucial in Cisco’s VTP (VLAN Trunking Protocol). VTP Configuration revision number must be cleared to zero on new Switch before deploying in any Network for safety. However, there is no specific command to do this. Below I will explain few procedures to reset VTP Configuration revision number on Cisco Switches. VTP is a Cisco-proprietary protocol that is available on most of the Cisco Catalyst series products. Steps to Reset the VTP Configuration Revision Number: You can easily reset the VTP configuration revision number by either of the two procedures provided below. 1. Reset the […]

Cisco VTP Version 3 – Features and Operation

VTP version 3 is the enhanced version to the previous VTP versions 1 and 2. This post covers the operation and important features & benefits of VTP version 3 when compared to VTP version 1 and 2. VTP Version 3 Important Features: Protection against data overwrites in case “wrong” database accidentally being inserted into a VTP domain. Support for extended VLANs up to 4096 Support for creation and advertising of PVLANs Support for propagation of other databases (not just VLAN data), specifically MST databases but there are hooks for more in the future. Improved server authentication(MD5) Interaction with VTP version 1 and VTP version 2 VTP Version 3 Operation: VTP version 3 introduces the concept of transferring an opaque database in situations where VTP version 1 and VTP version 2 interacted with the VLAN process directly. VTP version 3 supports for both VLAN instance and a separate MST instance. By […]

How to Configure VTP Pruning on Cisco Switch

VTP pruning increases the network bandwidth by reducing unnecessary flooded traffic, such as broadcast, multicast, unknown, and flooded unicast packets on trunk links. Without VTP pruning, a switch floods broadcast, multicast, and unknown unicast traffic across all trunk links within a VTP domain even though receiving switches might discard them. By default, VTP pruning is disabled. VTP pruning does not prune traffic from VLANs that are pruning-ineligible. VTP pruning blocks unneeded flooded traffic to VLANs on trunk ports that are included in the pruning-eligible list. Only VLANs included in the pruning-eligible list can be pruned. By default, VLANs 2 through 1001 are pruning eligible switch trunk ports. VTP pruning does not prune traffic from VLANs that are pruning-ineligible. VLAN 1 and VLANs 1002 to 1005 are always pruning-ineligible; traffic from these VLANs cannot be pruned. Extended-range VLANs (VLAN IDs higher than 1005) are also pruning-ineligible. VTP pruning is supported with […]

VLAN Access Control Lists configuration on Cisco Switch

In this post I will cover Vlan access control lists (VACLs), is also called VLAN access Map or VLAN Map. A VLAN Access-map allows us to filter incoming and outgoing traffic in a switch VLAN. VLAN access-list configuration is very similar to the Route-map configuration. You have to place the Vlan access-map on the whole Vlan When you want to filter traffic that is moving from one VLAN to anotherVLAN, which means that the incoming and outgoing traffic in a Vlan are filterd by the VLan access-map. We can apply a VLAN access-map to a Layer3 access-list and also to a mac access-list. We know that the usual access control list (ACL), which is the most well known concept, has an implied DENY IP ANY ANY at the end. Of course, a VACL has the same implied deny statement, but this is not recommended, because a normal ACL checks only […]

Difference between VTP Version 1 and Version 2 on Cisco Switches

There are three versions of VTP in Cisco Switches. VTP Version 3 is very new and will be available only in the latest IOS versions. Remember that all VTP is off by default. If you want to use VTP in your network, you must decide whether to use version 1 or version 2 or version 3. When you enable VTP on Switches, by default VTP operates in version 1 only. VTP version configuration on Cisco Switch You can configure VTP version using VTP version command on Cisco Switches. Cisco_Switch(config)#vtp version ? <1-2>  Set the adminstrative domain VTP version number Difference between VTP Version 1 and Version 2 VTP Version 2 supports additional features compared to VTP version 1. Version 1 is adequate for most systems that do not contain Token Ring feature. Many of the Version 2 features impose tighter management control on VTP, which could very well help avoid […]

Easy Way to quickly remove all Vlans on Cisco Switch

In work environment if you want to completely erase the whole switch configuration including all Vlans or range of Vlans that are already configured on the switch, you can do very quickly. In a Cisco switch, erasing the Vlan database is one thing and erasing the range of vlans that exist on the switch is another thing. It is a good practice to completely erase everything on a switch before using the switch in another part of your network. This is important in order to avoid any network conflicts because of any old configuration settings that are already configured on the switch. 1. Deleting the switch Vlans Database: You can find the complete Vlans configured list by executing the command “show vlan brief”. In this example you can see that there are 3 vlans configured on the switch. These vlans are stored in a file in flash memory called “vlan.dat”. […]