1 2 Previous Next 17 Replies Latest reply: Aug 21, 2019 7:53 AM by Sergey RSS

    Question

    Gowthamraj F

      Hi Guys,

       

      which VLANs are allowed on a Trunk link by default?


      guys any one tell me the answer for the above question.

       

       

       

      regards

      gowthamrajF




       

        • 1. Re: Question
          Steven Davidson

          1-4094

          • 2. Re: Question
            Gowthamraj F

            HI Steven

             

            thank you for your reply,

             

            i am not mentioned its Layer2 or Layer 3 switch if its layer 2 then it will be 1 to 1005 , if its Layer 3 switch then it will be 1 to 4094,so we can go with All active vlans are allowed by default. is it correct or i am wrong, if i am wrong brief me

             

            waiting for your response

            • 3. Re: Question
              Steven Davidson

              Default is that the entire range of possible VLANs is allowed.

              • 4. Re: Question
                Ing_Percy

                Hi!

                Gowthamraj F escribió:

                i am not mentioned its Layer2 or Layer 3 switch if its layer 2 then it will be 1 to 1005 , if its Layer 3 switch then it will be 1 to 4094,so we can go with All active vlans are allowed by default. is it correct or i am wrong, if i am wrong brief me

                Any trunk in L2 or L3 switches, by default:

                allowed-vlans.JPG

                Regards!

                • 5. Re: Question
                  Sergey

                  Gowthamraj,

                   

                  You are confusing allowed VLANs list with the VTP VLANs exchange on version 1 and 2. VTP versions 1 and 2 can only exchange VLAN information about standard range VLANs, and version 3 can exchange The entire VLAN range.

                  • 6. Re: Question
                    Gowthamraj F

                    Hi Sergey,

                     

                    can you explain briefly, sorry i am not getting ...

                     

                     

                    Regards

                    Gowthamraj F

                    • 7. Re: Question
                      Gowthamraj F

                      Thank you for your reply steven

                      • 8. Re: Question
                        Gowthamraj F

                        Thank you Ing_Percy

                        • 9. Re: Question
                          Samer

                          By default, any configured VLANs on the switch will be allowed

                           

                          check below:

                          Switch#show inter e0/0 sw     

                          Name: Et0/0

                          Switchport: Enabled

                          Administrative Mode: trunk

                          Operational Mode: trunk

                          Operational private-vlan: none

                          Trunking VLANs Enabled: ALL

                          Switch(config-if)#switchport trunk allowed vlan 3

                          Switch#show inter e0/0 sw

                          Name: Et0/0

                          Operational private-vlan: none

                          Trunking VLANs Enabled: 3

                          • 10. Re: Question
                            Sergey

                            Gowthamraj,

                             

                            The allowed VLAN range on a trunk port by default is 1-4094. This is a full range. There are two sub-ranges: 1-1005, which is called standard VLAN range and 1006 - 4094, which is called the extended VLAN range. The first one is what can be exchanged over VTP protocol version 1 and 2. In other words, VTP v1/2 can only share VLAN information about VLANs 1 - 1005. VTP version 3 can exchange VLAN information about VLANS 1 - 4094, so it includes both the standard VLAN range and extended VLAN range. But that does nothing to change what VLANs are actually permitted on a trunk port. The exchange of VLAN information and the actual permitted VLANs on a trunk port are not synchronised in any way. They are two completely independent processes.

                            • 11. Re: Question
                              Gowthamraj F

                              thank you for reply Sergey

                               

                              in case if the switch is supports 4094 vlans means, Reserved vlans are 0,1,4095 am i right?

                               

                              we can use 1002 to 1005 in case of if the switch is support 4049 vlan means.. vlan 0 where we can use it?

                               

                               

                              Regards

                              Gowthamraj F

                              • 12. Re: Question
                                Gowthamraj F

                                thank yo samer

                                • 13. Re: Question
                                  Sergey

                                  Gowthamraj,

                                   

                                  You can't use VLAN 0, the lowest VLAN number is 1. Reserved VLANs are 1002-1005. Everything above VLAN 1005 belongs to extended VLAN range, which can only be dynamically exchanged using VTP version 3. It is not a question of what switch supports. It is a question of what is allowed by default to pass over the trunk port. And by default it is every VLAN. But if you want to use VTP to replicate the VLAN information between switches, then you have limitations on VTP version 1 and version 2, only being able to replicate information about standard range VLANs.

                                  • 14. Re: Question
                                    Gowthamraj F

                                    Thank you sergey

                                     

                                    i have more one question

                                     

                                    R1 has been configured for OSPF authentication on its fa0/0 interface as shown here. which of the following is true about the configuration?

                                     

                                    interface fa0/0

                                    ip ospf authentication-key test

                                    ip ospf authentication

                                    ip ospf message-digest-key 2 md5 cisco

                                    router ospf 2

                                    area 0 authentication message-digest

                                     

                                    Answer:  R1 will attempt simple-text authentication on the LAN with key test

                                     

                                    can u explain me this question , how the router will take simple text authentication here..

                                     

                                    regards

                                    gowthamraj

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