Tài liệu học CCNA kỳ 3 ccna3 mod9 VTP

1 Module 9 – VTP CCNA 3 version 3.1 Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Contents • 9.1 Trunking • 9.2 VTP • 9.3 Inter-VLAN Routing Overview 2 Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Objectives • Explain the origins and functions of VLAN trunking • Describe how trunking enables the implementation of VLANs in a large network • Define IEEE 802.1Q • Define Cisco ISL • Configure and verify a VLAN trunk • Define VTP • Explain why VTP was developed • Describe the contents of VTP messages • List and define the three VTP modes • Configure and verify VTP on an IOS-based switch • Explain why routing is necessary for inter-VLAN communication • Explain the difference between physical and logical interfaces • Define subinterfaces • Configure inter-VLAN routing using subinterfaces on a router port Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Trunk Link • The history of trunking goes back to the origins of radio and telephony technologies. In radio technologies, a trunk is a single communications line that carries multiple channels of radio signals. • In the telephony industry, the trunking concept is associated with the telephone communication path or channel between two points. One of these two points is usually the Central Office (CO). 3 Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Create Trunks by using FDM • Shared trunks may also be created for redundancy between COs. • The concept that had been used by the telephone and radio industries was then adopted for data communications. • An example of this in a communications network is a backbone link between an MDF and an IDF. A backbone is composed of a number of trunks. Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com VLANs • At present, the same principle of trunking is applied to network switching technologies. • A trunk is a physical and logical connection between two switches across which network traffic travels 4 Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Trunking concepts • In the context of a VLAN switching environment, a trunk is a point-to-point link that supports several VLANs. The purpose of a trunk is to conserve ports when creating a link between two devices implementing VLANs • Trunking will bundle multiple virtual links over one physical link by allowing the traffic for several VLANs to travel over a single cable between the switches • Trunking is like a Highway Distributor. Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Frame Filtering • Trunking protocols were developed to effectively manage the transfer of frames from different VLANs on a single physical line. The trunking protocols establish agreement for the distribution of frames to the associated ports at both ends of the trunk. • Currently two types of trunking mechanisms exist, frame filtering and frame tagging. 5 Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Frame Tagging • Frame tagging has been adopted as the standard trunking mechanism by IEEE • Trunking protocols that use a frame tagging mechanism assign an identifier to the frames to make their management easier and to achieve a faster delivery of the frames. Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Inter-Switch Link Protocol • The unique physical link between the two switches is able to carry traffic for any VLAN. In order to achieve this, each frame sent on the link is tagged to identify which VLAN it belongs to. Different tagging schemes exist. The most common tagging schemes for Ethernet segments are listed below: • ISL – Cisco proprietary Inter-Switch Link protocol. • 802.1Q – IEEE standard that will be focused on in this section. 6 Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com VLANs and Trunking • VLAN frame tagging is an approach that has been specifically developed for switched communications. Frame tagging places a unique identifier in the header of each frame as it is forwarded throughout the network backbone. The identifier is understood and examined by each switch before any broadcasts or transmissions are made to other switches, routers, or end-station devices. Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com VLANs and Trunking • When the frame exits the network backbone, the switch removes the identifier before the frame is transmitted to the target end station. Frame tagging functions at Layer 2 and requires little processing or administrative overhead. • It is important to understand that a trunk link does not belong to a specific VLAN. The responsibility of a trunk link is to act as a conduit for VLANs between switches and routers. 7 Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Cisco IOS Software-based • To create or configure a VLAN trunk on a Cisco IOS command- based switch, configure the port first as a trunk and then specify the trunk encapsulation with the following commands: • Switchport mode trunk • Switchport trunk encapsulation isl Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Show port capabilities • Before attempting to configure a VLAN trunk on a port, determine what encapsulation the port can support. This can be done using the show port capabilities command. In the example, notice in the highlighted text that Port 2/1 will support only the IEEE 802.1Q encapsulation. 8 Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Show trunk • Verify that trunking has been configured and verify the settings by using the show trunk [mod_num/port_num] command from privileged mode on the switch. Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Trunking mode • The trunking modes available in Fast Ethernet and Gigabit Ethernet 9 Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com VTP Benefits • As the organization grows and additional switches are added to the network, each new switch must be manually configured with VLAN information. A single incorrect VLAN assignment could cause two potential problems: • Cross-connected VLANs due to VLAN configuration inconsistencies • VLAN misconfiguration across mixed media environments such as Ethernet and Fiber Distributed Data Interface (FDDI) • With VTP, VLAN configuration is consistently maintained across a common administrative domain. Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Trunk links • VTP is a messaging protocol that uses Layer 2 trunk frames to manage the addition, deletion, and renaming of VLANs on a single domain • VTP messages are encapsulated in either Cisco proprietary Inter-Switch Link (ISL) or IEEE 802.1Q protocol frames, and passed across trunk links to other devices. In IEEE 802.1Q frames a 4 byte field is added that tags the frame. Both formats carry the VLAN ID. • While switch ports are normally assigned to only a single VLAN, trunk ports by default carry frames from all VLANs. 10 Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com ISL Encapsulation Frame • When transmitting VTP messages to other switches in the network, the VTP message is encapsulated in a trunking protocol frame such as ISL or IEEE 802.1Q. Figure shows the generic encapsulation for VTP within an ISL frame. Họcviệnmạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com ISL Encapsulation Frame • The VTP header varies, depending upon the type of VTP message, but generally, four items are found in all VTP messages: - VTP protocol version: Either Version 1 or 2 - VTP message type: Indicates one of four types - Management domain name length: Indicates size of the name that follows - Management domain name: The name configured for the management domain [...]... To add a VTP client to an existing VTP domain, always verify that its VTP configuration revision number is lower than the configuration revision number of the other switches in the VTP domain Use the show vtp status command If a switch is added that has a revision number higher than the revision number in the VTP domain, it can erase all VLAN information from the VTP server and VTP domain Học viện... sending the VTP summary advertisement Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 14 VTP configuration • Two different versions of VTP are available, Version 1 and Version 2 The two versions are not interoperable If a switch is configured in a domain for VTP Version 2, all switches in the management domain must be configured for VTP Version 2 VTP Version 1 is the default VTP Version.. .VTP Mode Comparisions • VTP switches operate in one of three modes: - Server - Client - Transparent Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com VTP Mode Comparisions • • • VTP servers can create, modify, and delete VLAN and VLAN configuration parameters for the entire domain VTP servers save VLAN configuration information in the switch NVRAM VTP servers send VTP messages... Switch(vlan) #vtp v2-mode Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 15 Configure VTP Domain • • • To create a management domain use the following command: Switch(vlan) #vtp domain cisco The domain name can be between 1 and 32 characters The password must be between 8 and 64 characters long Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Add a new switch to an Existing VTP Domain... the specific features that VTP Version 2 offers are not offered in VTP Version 1 The most common feature that is needed is Token Ring VLAN support Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Configure VTP Version • • • To configure the VTP version on a Cisco IOS command-based switch, first enter VLAN database mode Use the following command to change the VTP version number on a set... NVRAM VTP servers send VTP messages out to all trunk ports VTP clients cannot create, modify, or delete VLAN information This mode is useful for switches lacking memory to store large tables of VLAN information The only role of VTP clients is to process VLAN changes and send VTP messages out all trunk ports Switches in VTP transparent mode forward VTP advertisements but ignore information contained in... a change in its VLAN status Except for forwarding VTP advertisements, VTP is disabled on a transparent switch Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 11 VTP Operation • • VLANs detected within the advertisements serve as notification to the switch that traffic with the newly defined VLAN IDs may be expected Switch C transmits a VTP database entry with additions or deletions to... switch, use the following command: Switch(vlan) #vtp {client | server | transparent} Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Show VTP status This command is used to verify VTP configuration settings on a Cisco IOS command-based switch • This command is used to display statistics about advertisements sent and received on the switch Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com... the interface Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 24 Summary • • • • • • • • • • • • • • The origins and functions of VLAN trunking How trunking enables the implementation of VLANs in a large network IEEE 802.1Q Cisco ISL Configuring and verifying a VLAN trunk Definition of VLAN Trunking Protocol (VTP) Why VTP was developed The contents of VTP messages The three VTP modes Configuring... 192.168.1.1 then 192.168.1.2, 192.168.1 .3, and 192.1.1.4 are the IP addresses of devices attached to subinterface 2 Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com Subinterfaces Preparation • In order to route between VLANs with subinterfaces, a subinterface must be created for each VLAN Học viện mạng Cisco Bách Khoa - Website: www.ciscobachkhoa.com 23 Inter-VLAN Routing • Before any of