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tetu04
New Contributor III

Multiple LAN interfaces on 908e Gen3

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Hello all,

I have a question about setting up multiple LAN interfaces that I needed some clarification on. Let's say that I have a 908e Gen3 and since I have 3 Ethernet ports, I could use one for the WAN and use different subnets for Data and Voice. In all my deployments I most often break up whichever Interface I choose to use for LAN and create sub-interfaces. If for some reason I do choose to implement 2 ethernet interfaces for Data and Voice (native vlan 1 for data, and 2 for voice), what would be the best practice in configuring the switchports uplinks to the ethernet interfaces? Would I trunk them both, or configure them as "switchport mode access" and "switchport mode access vlan 2"?

Thanks in advance,

Adrian

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jayh
Honored Contributor
Honored Contributor

Re: Multiple LAN interfaces on 908e Gen3

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If you use two separate interfaces on the 908e, then you'll configure switchport access vlan [data vlan] on the switch port that physically connects to the interface configured for data on the 908e and switchport access vlan [voice vlan] on the switch port that physically connects to the interface configured for voice on the 908e.

The 908e will have no subinterfaces configured, just two Ethernet interfaces, one data and one voice (plus possibly the third for the WAN).

Because there are no subinterfaces on the 908e and the switch ports are configured as access ports, traffic on each of the wires will not have any 802.1q tags. One will have voice traffic, the other will have data traffic.

Does this make sense? 

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jayh
Honored Contributor
Honored Contributor

Re: Multiple LAN interfaces on 908e Gen3

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It makes little difference from a logical standpoint.  If you have completely different physical networks with different switches and drops to the desktop for voice and data, it makes sense to keep them physically separate all the way.

If on the other hand you're trunking the voice and data VLANs to the desktop with different VLANs on a single wire, then I would continue to trunk them to the Gen. 3 on subinterfaces.  This leaves a spare Ethernet port that can be used for something else in the future and saves a port on the switch as well.

tetu04
New Contributor III

Re: Multiple LAN interfaces on 908e Gen3

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Jayh,

Thanks for the quick response. Sorry for not being too clear, but the question was more geared towards the switchport configurations that will connect to the 908e. If I use only one of the 908e's ethernet interfaces and create subinterfaces, the switchport connecting that will be trunked. How will the switchports look if I use a separate ethernet interface for data and voice. I will use two separate switchports but should they both be trunked, or do they have to be configured as  "switchport mode access" (data) and "switchport mode access vlan 2" (voice)?

jayh
Honored Contributor
Honored Contributor

Re: Multiple LAN interfaces on 908e Gen3

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If you use two separate interfaces on the 908e, then you'll configure switchport access vlan [data vlan] on the switch port that physically connects to the interface configured for data on the 908e and switchport access vlan [voice vlan] on the switch port that physically connects to the interface configured for voice on the 908e.

The 908e will have no subinterfaces configured, just two Ethernet interfaces, one data and one voice (plus possibly the third for the WAN).

Because there are no subinterfaces on the 908e and the switch ports are configured as access ports, traffic on each of the wires will not have any 802.1q tags. One will have voice traffic, the other will have data traffic.

Does this make sense? 

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tetu04
New Contributor III

Re: Multiple LAN interfaces on 908e Gen3

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Jayh,

Thank you for the clarification. What would happen if the switch ports are trunked and they connect to the separate data/voice Ethernet interfaces?

jayh
Honored Contributor
Honored Contributor

Re: Multiple LAN interfaces on 908e Gen3

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It wouldn't be recommended, would be a bad idea, and probably won't work at all, but whichever VLAN is native to the trunked switch interface might be able to communicate with that interface's configured network.  Any non-native VLANs would not. 

Most likely, the switch will detect that it is configured as a trunk and the other side is not and error-disable the port. (That's what Brand C does.)

tetu04
New Contributor III

Re: Multiple LAN interfaces on 908e Gen3

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Makes sense. Thanks Jayh!