• The summary advertisement contains the VTP domain name, the current revision number, and other VTP configuration details. Summary[r]
(1)CCNA – Semester 3
Chapter 4: VTP
(2)Objectives
• Explain the role of VTP in a converged switched network
• Describe the operation of VTP including domains, modes, advertisements, and pruning
(3)(4)What is VTP?
(5)(6)VTP Components
• VTP Domain: Consists of one or more interconnected
(7)VTP Components
• VTP Modes: A switch can be configured in one of three
modes:
– Server
– Client
(8)VTP Components
• VTP Advertisements: VTP uses a hierarchy of
(9)VTP Components
• VTP Pruning:
VTP pruning increases network available bandwidth by restricting flooded traffic to those trunk links that the traffic must use to reach the destination devices 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
(10)(11)Default VTP Configuration
• VTP Versions = 1
• VTP Domain Name = null
• VTP Mode = Server
• Config Revision = 0
(12)Show vtp status command
• VTP Version: Displays the VTP version the switch is
capable of running By default, the switch implements version 1, but can be set to version
• Configuration Revision: Current configuration revision
number on this switch You will learn more about revisions numbers in this chapter
• Maximum VLANs Supported Locally: Maximum number of
VLANs supported locally
• Number of Existing VLANs: Number of existing VLANs
• VTP Operating Mode: Can be server, client, or transparent
• VTP Domain Name: Name that identifies the administrative
(13)Show vtp status command
• VTP Pruning Mode: Displays whether pruning is enabled or
disabled
• VTP V2 Mode: Displays if VTP version mode is enabled
VTP version is disabled by default
• VTP Traps Generation: Displays whether VTP traps are
sent to a network management station
• MD5 Digest: A 16-byte checksum of the VTP configuration
• Configuration Last Modified: Date and time of the last
configuration modification Displays the IP address of the
(14)VTP Domains
• VTP allows you to separate your network into smaller
management domains to help reduce VLAN management
• It limits the extent to which configuration changes are propagated in the network if an error occurs
• A VTP domain consists of one switch or several
interconnected switches sharing the same VTP domain name
• A switch can be a member of only one VTP domain at a time
(15)VTP Domains
VTP Domain Name Propagation
(16)VTP Advertising
VTP Frame Structure
(17)VTP Advertising
(18)VTP Advertising
VTP Message Contents
• VTP frames contain the following fixed-length global domain information:
• VTP domain name
• Identity of the switch sending the message, and the time it was sent
• MD5 digest VLAN configuration, including maximum transmission unit (MTU) size for each VLAN
• Frame format: ISL or 802.1Q
VTP frames contain the following information for each configured VLAN:
• VLAN IDs (IEEE 802.1Q)
• VLAN name
• VLAN type
(19)VTP Advertising
VTP Revision Number
• The configuration revision number is a 32-bit number that indicates the level of revision for a VTP frame The default configuration number for a switch is zero Each time a
VLAN is added or removed, the configuration revision number is incremented
• The configuration revision number determines whether the configuration information received from another
VTP-enabled switch is more recent than the version stored on the switch
(20)Summary Advertisements
• The summary advertisement contains the VTP domain name, the current revision number, and other VTP configuration details Summary
advertisements are sent:
– Every minutes by a VTP server or client to inform neighboring VTP-enabled switches of the current VTP configuration revision number for its VTP domain
– Immediately after a configuration has been made
– Subset Advertisements
Subset Advertisements
• A subset advertisement contains VLAN information Changes that trigger the subset advertisement include:
– Creating or deleting a VLAN
– Suspending or activating a VLAN
(21)Request Advertisements
• When a request advertisement is sent to a VTP server in the same VTP domain, the VTP server responds by sending a summary advertisement and then a subset advertisement Request advertisements are sent if:
– The VTP domain name has been changed
– The switch receives a summary advertisement with a higher configuration revision number than its own
– A subset advertisement message is missed for some reason
– The switch has been reset
(22)(23)(24)VTP Modes
• A Cisco switch, configured with Cisco IOS software, can be configured in either server, client, or transparent mode
– Server Mode
– Client Mode
(25)VTP Pruning
• VTP pruning prevents unnecessary flooding of broadcast information from one VLAN across all trunks in a VTP
domain
• VTP pruning permits switches to negotiate which VLANs are assigned to ports at the other end of a trunk and, hence,
(26)VTP Pruning
(27)VTP Pruning
VTP Pruning
(28)(29)(30)Configuring VTP
• Configure the VTP Server
– (config)# vtp mode {server}
• Configure the VTP domain name
(31)Configuring VTP
• Configure the VTP Client
(32)Configuring VTP
• Use the show vtp counters command to confirm that the advertisements took place
Verify
• Use the show VTP status command to verify the following:
– Configuration revision number
– The number of VLANs
(33)Troubleshooting VTP Configurations
• Common VTP Configuration Issues
– Incompatible VTP Versions
– VTP Password Issues
– Incorrect VTP Mode Name
(34)Troubleshooting VTP Configurations
• Incompatible VTP Versions
– VTP versions and are incompatible with each other
– Make sure all switches are running the same VTP version
– Solution: (config)#vtp version number
• VTP Password Issues
– Ensure passwords are all the same on all VTP enabled switches in the VTP domain
– By default a Cisco switch does not use a VTP password
– When a VTP advertisement is received Cisco switches not automatically set the VTP password parameter
(35)Troubleshooting VTP Configurations
• Incorrect VTP Domain Name
– The VTP domain name is a key parameter that is set on a switch
– If a switch receives the wrong VTP advertisement, the switch discards the message If the discarded message contains legitimate configuration information, the switch does not synchronize its VLAN database as expected
– Solution: (config)#vtp domain domain-name
• Switches Set to VTP Client Mode
– All switches are VTP client Because the VTP client
switches not store the VLAN information in NVRAM, they need to refresh the VLAN information after a reload
(36)Troubleshooting VTP Configurations
• Incorrect Revision Number
• Solution: Reset Revision Number
(37)Managing VLANs on a VTP Server
(38)Managing VLANs on a VTP Server
(39)Summary
• VTP simplifies VLAN administration across multiple Cisco Catalyst switches by replicating VLAN configurations between switches
• A VTP domain defines which switches in a network are to be configured similarly with respect to the VLAN configuration
• A Cisco Catalyst switch can be configured for one of three VTP operational modes: Server, Client, or Transparent
• VTP server mode allows for the creation, deletion, and modification of VLANs
• VTP client mode prevents modification of the VLANs and can only receive VLAN information through VTP advertisements
• VTP transparent mode allows for the creation, deletion, and modification of local VLANs, including extended range VLANs VLAN information is not synchronized with other switches
• VTP Passwords can be used to limit synchronization between switches configured with the same VTP domain
• VTP pruning can improve the overall bandwidth over trunk links by
limiting flood traffic to switches that contain active VLANs specific for the flood traffic