VLAN Trunking Protocol
VLAN Trunking Agreement (VTP) is a Layer 2 messaging agreement that maintains VLAN
configuration bendability by managing the addition, deletion, and renaming of a VLAN on
a network-wide basis. VTP minimizes misconfigurations and agreement inconsistencies
Table 11-2 LLDP TLV Types
Type Name
0 End of LLPD, it signals that there is no added TLV afterwards this one.
1 Chassis ID.
2 Port ID.
3 TTL.
4 Port description.
5 System name.
6 System description.
7 System capabilities (router, switch, and so on).
8 Administration address.
127 Reserved for bell-ringer extensions and IEEE extensions: built-in VLAN for untagged
frames, ability of Ethernet class.
Chassis ID TLV
Port ID TLV
Time to Live TLV
Other Optional TLV
End of LLDP TLV
VLAN Trunking Agreement 171
that can aftereffect in several problems, such as alike VLAN names and incorrect VLANtype
specifications. A VTP area (also accepted as a VLAN administration domain) is made
up of one or added commutual switches that allotment the aforementioned VTP area name. A switch
can be configured to be in one—and alone one—VTP domain. You can accomplish all-around VLAN
configuration changes for the area application either the command-line interface (CLI) or
Simple Network Administration Agreement (SNMP).
VTP runs anon over Layer 2 application the aforementioned Ethernet multicast 0100.0CCC.CCCC as
CDP and as a SNAP encapsulation with agreement blazon 20-03 (in the SNAP header).
Advertisement packets are beatific by VTP servers to VTP clients. Audience can additionally appeal a
VLAN database agreement by application requests. Figure 11-4 describes the packet format
for the latest adaptation of VTP (version 3).
Figure 11-4 VTP Adaptation 3 Advertisement Packet Format
32 Bits
Version
Management Area (Padded to 32 Bytes)
Configuration Revision Number
Updater Identity
Update Timestamp
MD5 HMAC
Code Followers Mgmt. D. Length
VTP adaptation 3 consists of the afterward elements:
• Administration Domain. Each about-face belongs to a administration area and listens
only to VTP packets from the aforementioned administration domain.
• Administration Area Length. Length of the administration area name.
• MD5 HMAC. The Assortment Bulletin Authentication Code (HMAC) of the message. It is
the bulletin abstract algorithm 5 (MD5) assortment of the VTP bulletin and a preshared key
(shared by all switches and VTP servers in a VTP domain).
• Agreement Revision Number. Every time the VTP server changes the VLAN
database, this cardinal is incremented. This allows the applicant to analysis whether its local
version is actual and whether to acquire a VLAN database from a server.
• Updater Identity. Identity of the VTP server.
• Amend Timestamp. Time back this agreement was updated.
A about-face artlessly uses the Administration Area to analysis whether the VTP packet is to be
recognized and parsed. The Updater fields acquiesce a about-face to apperceive which VTP server has
initiated the manual of this VTP update. The HMAC authenticates the VTP packet.
The MD5 HMAC and Administration Area abide in versions 1, 2, and 3 of VTP.