Cisco Catalyst 3850 router VLAN bridge no routing

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New to Cisco stuff so bear with me (only a little L2 Procurve experience). I have a development network connected to an Aruba/HPE managed switch feeding a trunk with tagged VLAN's to an internal network Cisco C2960. I am not in charge of the C2960, but it looks like the VLAN's appear to be sending and receiving correctly, based on some testing from a hypervisor server hanging off the C2960. Now, this C2960 has an trunk uplink to a C3850 router which should have the necessary VLAN's configured. From the C3850 is another trunk to yet another C2960, with the correct trunk settings for the VLAN's I want to haul from the development network to the second switch.



I can't do basic pings on the dev VLAN's from the second switch. Some people involved with setting up the C3850 said I would have to add an IP in the subnet of the VLAN at the Cisco router to make it bridge the VLAN's from the first to the second switch, but I don't want routing and setting a next hop seems bizarre. Ideally, I want to do no routing (more like a managed switch transparently forwarding VLAN's). Since the Cisco router is currently a core router, I can't ask to make the whole thing behave like a dumb switch.



Is there a proper way to transparently bridge the VLAN's between ports on the router without routing or needing an IP at the router, while preserving existing routing, so I can send traffic from the second C2960 to the Aruba switch?










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    up vote
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    New to Cisco stuff so bear with me (only a little L2 Procurve experience). I have a development network connected to an Aruba/HPE managed switch feeding a trunk with tagged VLAN's to an internal network Cisco C2960. I am not in charge of the C2960, but it looks like the VLAN's appear to be sending and receiving correctly, based on some testing from a hypervisor server hanging off the C2960. Now, this C2960 has an trunk uplink to a C3850 router which should have the necessary VLAN's configured. From the C3850 is another trunk to yet another C2960, with the correct trunk settings for the VLAN's I want to haul from the development network to the second switch.



    I can't do basic pings on the dev VLAN's from the second switch. Some people involved with setting up the C3850 said I would have to add an IP in the subnet of the VLAN at the Cisco router to make it bridge the VLAN's from the first to the second switch, but I don't want routing and setting a next hop seems bizarre. Ideally, I want to do no routing (more like a managed switch transparently forwarding VLAN's). Since the Cisco router is currently a core router, I can't ask to make the whole thing behave like a dumb switch.



    Is there a proper way to transparently bridge the VLAN's between ports on the router without routing or needing an IP at the router, while preserving existing routing, so I can send traffic from the second C2960 to the Aruba switch?










    share|improve this question







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      up vote
      2
      down vote

      favorite









      up vote
      2
      down vote

      favorite











      New to Cisco stuff so bear with me (only a little L2 Procurve experience). I have a development network connected to an Aruba/HPE managed switch feeding a trunk with tagged VLAN's to an internal network Cisco C2960. I am not in charge of the C2960, but it looks like the VLAN's appear to be sending and receiving correctly, based on some testing from a hypervisor server hanging off the C2960. Now, this C2960 has an trunk uplink to a C3850 router which should have the necessary VLAN's configured. From the C3850 is another trunk to yet another C2960, with the correct trunk settings for the VLAN's I want to haul from the development network to the second switch.



      I can't do basic pings on the dev VLAN's from the second switch. Some people involved with setting up the C3850 said I would have to add an IP in the subnet of the VLAN at the Cisco router to make it bridge the VLAN's from the first to the second switch, but I don't want routing and setting a next hop seems bizarre. Ideally, I want to do no routing (more like a managed switch transparently forwarding VLAN's). Since the Cisco router is currently a core router, I can't ask to make the whole thing behave like a dumb switch.



      Is there a proper way to transparently bridge the VLAN's between ports on the router without routing or needing an IP at the router, while preserving existing routing, so I can send traffic from the second C2960 to the Aruba switch?










      share|improve this question







      New contributor




      Asteroza is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      New to Cisco stuff so bear with me (only a little L2 Procurve experience). I have a development network connected to an Aruba/HPE managed switch feeding a trunk with tagged VLAN's to an internal network Cisco C2960. I am not in charge of the C2960, but it looks like the VLAN's appear to be sending and receiving correctly, based on some testing from a hypervisor server hanging off the C2960. Now, this C2960 has an trunk uplink to a C3850 router which should have the necessary VLAN's configured. From the C3850 is another trunk to yet another C2960, with the correct trunk settings for the VLAN's I want to haul from the development network to the second switch.



      I can't do basic pings on the dev VLAN's from the second switch. Some people involved with setting up the C3850 said I would have to add an IP in the subnet of the VLAN at the Cisco router to make it bridge the VLAN's from the first to the second switch, but I don't want routing and setting a next hop seems bizarre. Ideally, I want to do no routing (more like a managed switch transparently forwarding VLAN's). Since the Cisco router is currently a core router, I can't ask to make the whole thing behave like a dumb switch.



      Is there a proper way to transparently bridge the VLAN's between ports on the router without routing or needing an IP at the router, while preserving existing routing, so I can send traffic from the second C2960 to the Aruba switch?







      cisco vlan bridge cisco-3850






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      asked 7 hours ago









      Asteroza

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          2 Answers
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          That should be possible - provided that...



          • the same set (or at least a common subset) of VLAN IDs is used across the chain of switches

          • this same (sub)set of VLANs is configured/added on all the switches along the path

          • this same (sub)set of VLANs is "allowed" and "tagged" on all segments (the inter-switch links) along the path.

          • some very diligent attention is directed towards spanning tree interoperability between HP/Aruba and Cisco (the latter by default run Cisco's own PVST or RPVST, the former usually use the IEEE variants STP, RSTP or MST).

          • the admins of the said Cat2960s and Cat3850 are willing to add "your" set of VLANs to their device (which they might deny, because they might want to run their Cat3850 as a L3 device only)

          The Cat3850 and the Cat2960s are definitely capable of what you intend to do, which is what VLANs, trunking and switching are all about. There is no technical reason why the Cat3850 should get any (additional) IP address(es) to bridge these VLANs. But - there may be operational guidelines preventing it.






          share|improve this answer



























            up vote
            1
            down vote













            To get traffic from one network (VLAN) to another requires a router. Even if you bridge the VLANs at layer-2, the devices on the different networks will be unable to communicate. A host will look at the destination address, and it can tell that it is on a different network. If it is, then it will send the frame to its configured gateway (router). A router is a host on the LAN that knows how to forward packets to a different network.



            The purpose of VLANs is to break up the network into separate layer-2 domains, and it requires a router (at layer-3) to forward packets between the separate networks.






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              2 Answers
              2






              active

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              2 Answers
              2






              active

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              active

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              up vote
              2
              down vote













              That should be possible - provided that...



              • the same set (or at least a common subset) of VLAN IDs is used across the chain of switches

              • this same (sub)set of VLANs is configured/added on all the switches along the path

              • this same (sub)set of VLANs is "allowed" and "tagged" on all segments (the inter-switch links) along the path.

              • some very diligent attention is directed towards spanning tree interoperability between HP/Aruba and Cisco (the latter by default run Cisco's own PVST or RPVST, the former usually use the IEEE variants STP, RSTP or MST).

              • the admins of the said Cat2960s and Cat3850 are willing to add "your" set of VLANs to their device (which they might deny, because they might want to run their Cat3850 as a L3 device only)

              The Cat3850 and the Cat2960s are definitely capable of what you intend to do, which is what VLANs, trunking and switching are all about. There is no technical reason why the Cat3850 should get any (additional) IP address(es) to bridge these VLANs. But - there may be operational guidelines preventing it.






              share|improve this answer
























                up vote
                2
                down vote













                That should be possible - provided that...



                • the same set (or at least a common subset) of VLAN IDs is used across the chain of switches

                • this same (sub)set of VLANs is configured/added on all the switches along the path

                • this same (sub)set of VLANs is "allowed" and "tagged" on all segments (the inter-switch links) along the path.

                • some very diligent attention is directed towards spanning tree interoperability between HP/Aruba and Cisco (the latter by default run Cisco's own PVST or RPVST, the former usually use the IEEE variants STP, RSTP or MST).

                • the admins of the said Cat2960s and Cat3850 are willing to add "your" set of VLANs to their device (which they might deny, because they might want to run their Cat3850 as a L3 device only)

                The Cat3850 and the Cat2960s are definitely capable of what you intend to do, which is what VLANs, trunking and switching are all about. There is no technical reason why the Cat3850 should get any (additional) IP address(es) to bridge these VLANs. But - there may be operational guidelines preventing it.






                share|improve this answer






















                  up vote
                  2
                  down vote










                  up vote
                  2
                  down vote









                  That should be possible - provided that...



                  • the same set (or at least a common subset) of VLAN IDs is used across the chain of switches

                  • this same (sub)set of VLANs is configured/added on all the switches along the path

                  • this same (sub)set of VLANs is "allowed" and "tagged" on all segments (the inter-switch links) along the path.

                  • some very diligent attention is directed towards spanning tree interoperability between HP/Aruba and Cisco (the latter by default run Cisco's own PVST or RPVST, the former usually use the IEEE variants STP, RSTP or MST).

                  • the admins of the said Cat2960s and Cat3850 are willing to add "your" set of VLANs to their device (which they might deny, because they might want to run their Cat3850 as a L3 device only)

                  The Cat3850 and the Cat2960s are definitely capable of what you intend to do, which is what VLANs, trunking and switching are all about. There is no technical reason why the Cat3850 should get any (additional) IP address(es) to bridge these VLANs. But - there may be operational guidelines preventing it.






                  share|improve this answer












                  That should be possible - provided that...



                  • the same set (or at least a common subset) of VLAN IDs is used across the chain of switches

                  • this same (sub)set of VLANs is configured/added on all the switches along the path

                  • this same (sub)set of VLANs is "allowed" and "tagged" on all segments (the inter-switch links) along the path.

                  • some very diligent attention is directed towards spanning tree interoperability between HP/Aruba and Cisco (the latter by default run Cisco's own PVST or RPVST, the former usually use the IEEE variants STP, RSTP or MST).

                  • the admins of the said Cat2960s and Cat3850 are willing to add "your" set of VLANs to their device (which they might deny, because they might want to run their Cat3850 as a L3 device only)

                  The Cat3850 and the Cat2960s are definitely capable of what you intend to do, which is what VLANs, trunking and switching are all about. There is no technical reason why the Cat3850 should get any (additional) IP address(es) to bridge these VLANs. But - there may be operational guidelines preventing it.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered 5 hours ago









                  Marc 'netztier' Luethi

                  2,404317




                  2,404317




















                      up vote
                      1
                      down vote













                      To get traffic from one network (VLAN) to another requires a router. Even if you bridge the VLANs at layer-2, the devices on the different networks will be unable to communicate. A host will look at the destination address, and it can tell that it is on a different network. If it is, then it will send the frame to its configured gateway (router). A router is a host on the LAN that knows how to forward packets to a different network.



                      The purpose of VLANs is to break up the network into separate layer-2 domains, and it requires a router (at layer-3) to forward packets between the separate networks.






                      share|improve this answer
























                        up vote
                        1
                        down vote













                        To get traffic from one network (VLAN) to another requires a router. Even if you bridge the VLANs at layer-2, the devices on the different networks will be unable to communicate. A host will look at the destination address, and it can tell that it is on a different network. If it is, then it will send the frame to its configured gateway (router). A router is a host on the LAN that knows how to forward packets to a different network.



                        The purpose of VLANs is to break up the network into separate layer-2 domains, and it requires a router (at layer-3) to forward packets between the separate networks.






                        share|improve this answer






















                          up vote
                          1
                          down vote










                          up vote
                          1
                          down vote









                          To get traffic from one network (VLAN) to another requires a router. Even if you bridge the VLANs at layer-2, the devices on the different networks will be unable to communicate. A host will look at the destination address, and it can tell that it is on a different network. If it is, then it will send the frame to its configured gateway (router). A router is a host on the LAN that knows how to forward packets to a different network.



                          The purpose of VLANs is to break up the network into separate layer-2 domains, and it requires a router (at layer-3) to forward packets between the separate networks.






                          share|improve this answer












                          To get traffic from one network (VLAN) to another requires a router. Even if you bridge the VLANs at layer-2, the devices on the different networks will be unable to communicate. A host will look at the destination address, and it can tell that it is on a different network. If it is, then it will send the frame to its configured gateway (router). A router is a host on the LAN that knows how to forward packets to a different network.



                          The purpose of VLANs is to break up the network into separate layer-2 domains, and it requires a router (at layer-3) to forward packets between the separate networks.







                          share|improve this answer












                          share|improve this answer



                          share|improve this answer










                          answered 7 hours ago









                          Ron Maupin♦

                          58.7k1057105




                          58.7k1057105




















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