?
- Simplify VLAN information library synchronization in large Campus Networks (same VTP management domain)
- Only synchronize VLAN Information
- Support for trunk links between switches
1. VTP Mode
The VTP configuration revision number in transparent mode is always 0.
2. VTP operations
- The VTP protocol sends a VTP announcement on the trunk link through the multicast address 0100-0ccc-cccc;
- The vtp server and clients synchronize the database with the highest revision number;
- The VTP protocol sends a VTP announcement or changes every five minutes;
3. VTP ConfigurationSwitch (config) # VTP domain Cisco configuration VTP domain name switch (config) # VTP mode {server | client | transparent} configure VTP mode switch (config) # VTP password X (optional) configure the password switch # Show VTP Password
4. VTP Problems
If the configuration revision number Of The VTP client is higher than that of the server, the client can overwrite the server VLAN information.
The configuration revision numbers of the server and client are the same, but the VLAN information is different. In this case, an error is reported, indicating MD5 Digest checksum mismatch.
5. VTP pruning
1) Purpose: To pass VLAN Information
SW1 and sw2 are configured as VTP mode client, and sw3 is configured as VTP Mode Server. You can learn how to create vlansw1 and sw2 10, 20, and 30 on sw3, if you are a three-year-old child, you can do this. For more information, see sw3 # sh VTP status VTP version capable: 1 to 3vtp version running: 1vtp Domain Name: ccnpvtp pruning mode: disabled !! The default VTP prunnig is the disabled VTP traps generation: disableddevice ID: 000a. 8a07. 8280 configuration last modified by 0.0.0.0 at 3-5-93 00: 11: 48 local Updater ID is 0.0.0.0 (no valid Interface found) feature VLAN: ------------ VTP operating mode: servermaximum VLANs supported locally: 1005 number of existing VLANs: 8 configuration revision: 15md5 Digest: 0x49 0x3c 0x1f 0x79 0x15 0x00 0xc7 0xae 0x0e 0xdc 0xdd 0xef 0x93 0xa5 0xb6 0x26
2) Objective: To test the VLAN trunk allowedcontinue. After dividing the interfaces connecting SW1 and sw2 into vlan10, the two PCs can communicate with each other. At this time, let's take a look at the trunk status on SW1: SW1 # sh int trunk port mode encapsulation status native vlanfa0/20 on 802.1Q trunking 1 port VLANs allowed on trunkfa0/20 1-4094 port VLANs allowed and active in management domainfa0/20, 10, 20, 30 Port VLANs in Spanning Tree forwarding state and not prunedfa0/20, 10, 20, 30 !! When the VTP prunnig is disabled, trunk releases the traffic of all VLANs by default. This is the case in sw2 and sw3. Next, we will go to the fa0/20 interface of SW1, perform the switchport trunk allowed VLAN remove 10 and trim the vlan10 traffic. At this time, the ping between PCs will fail. Then go to R1: SW1 # sh int trunk port mode encapsulation status native vlanfa0/20 on 802.1Q trunking 1 port VLANs allowed on trunkfa0/20 1-9, 11-4094 port VLANs allowed and active in management domainfa0/20, 30 Port VLANs in Spanning Tree forwarding state and Not prunedfa0/20, 20, 30 Note: at this moment, although SW1 has trimmed vlan10 traffic on the fa0/20 Port, sw3's fa0/20 Ports still allow this traffic, however, in any case, there is no mutual access between PCs. Here is just a demonstration to understand the role of allowed VLAN. Of course, this is a manual trim method.
3) Objective: To test VTP pruningremove the command configured on SW1 in step 2 and restore the experiment environment. Next we will enable VTP pruning on sw3, that is, the vtp server. Sw3 # sh VTP stvtp version capable: 1 to 3vtp version running: 1vtp Domain Name: ccnpvtp pruning mode: enabledvtp traps generation: disableddevice ID: 000a. 8a07. 8280 configuration last modified by 0.0.0.0 at 3-5-93 02: 01: 49 Local Updater ID is 0.0.0.0 (no valid Interface found) feature VLAN: ------------ VTP operating mode: servermaximum VLANs supported locally: 1005 number of existing VLANs: 8 Configuration revision: 17md5 Digest: 0x73 0x52 0x60 0xe7 0x4d 0xa5 0xc7 0x4f 0xca 0x3d 0x6f 0x1d 0x3f 0x23 0x03 0xbb after enabling VTP pruning on sw3 in vtp server mode, both SW1 and sw2 of the client can learn and enable their own VTP pruning. In this way, all three vswitches perform VTP packet interaction and inform themselves that there is a local VLAN for accessing the user. VLANs without users will be automatically trimmed. Let's take a look: SW1 # Show int trunk port mode encapsulation status native vlanfa0/20 on 802.1Q trunking 1 port VLANs allowed on trunkfa0/20 1-4094 port VLANs allowed and active in management domainfa0/20, 10, 20, 30 Port VLANs in Spanning Tree forwarding state and not prunedfa0/20, 10 !! On R1, fa0/20 ports are trimmed with only VLAN 1, 10sw2, and sw3. Note, at this moment, we have not configured any static allowed VLAN configurations on the trunk port. Next, we will remove the vlan10 port on sw2, no switchport access VLAN on fa0/2, so that no vlan10 user is available on sw2. sw2 will flood the message so that other switches can know. After sw3 receives this message, it will know that sw2 no longer has vlan10 users, so it will no longer need vlan10 traffic. Therefore, it will trim vlan10 on its fa0/22 Port: sw3 # sh int Tru port mode encapsulation status native vlanfa0/20 on 802.1Q trunking 1fa0/22 desirable N-isl trunking 1 port VLANs allowed on random/20 1-4094fa0/22 1-4094 port VLANs allowed and active in management domainfa0/20, 10, 20, 30fa0/22, 20, 30 Port VLANs in Spanning Tree forwarding state and not prunedfa0/20 1, 10fa 0/22 1 !! Last Note: • VTP pruning can only be enabled on server mode • After server mode is enabled, the client will automatically enable pruning • VTP pruning is disabled by default [from: http://blog.sina.com.cn/s/blog_5ec353710101d9g7.html]
[VTP] Cisco VTP Protocol notes
