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Cablenut9
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VLANs and address assignment

Mon Jun 21, 2021 6:52 pm

If I have some interface, like ether1, and a bunch of VLAN interfaces on it, like vlan2 and vlan3, does ether1's IP address "carry over" to the VLANs? If so, is there a way to disable this?
 
nagylzs
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Re: VLANs and address assignment

Mon Jun 21, 2021 7:04 pm

If I have some interface, like ether1, and a bunch of VLAN interfaces on it, like vlan2 and vlan3, does ether1's IP address "carry over" to the VLANs? If so, is there a way to disable this?
If you have a bridge, and you have ether1 added as a tagged port, then you won't want to assign an IP address to the ether1 interface itself. And it won't have an IP address unless you add one (with /ip address add or dhcp-client etc.)
 
nagylzs
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Re: VLANs and address assignment

Mon Jun 21, 2021 7:08 pm

I think it is the same if ether1 is not a port of a bridge. If you don't add an IP address to ether1 itself, then it won't have an IP address.
 
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mkx
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Re: VLANs and address assignment

Mon Jun 21, 2021 8:36 pm

If I have some interface, like ether1, and a bunch of VLAN interfaces on it, like vlan2 and vlan3, does ether1's IP address "carry over" to the VLANs?

No, IP address is bound to interface. In your case ether1 is interface for untagged frames passing ether1 port. For VLAN interfaces ether1 is simply underlying hardware port.

One should not forget that ROS, being Routing OS, will gladly route packets between different interfaces (including ether1 and associated vlanX interfaces). If traffic between these interfaces is not desired, one can configure firewall rules to block it.
 
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anav
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Re: VLANs and address assignment

Mon Jun 21, 2021 10:41 pm

So MKX
you could have

a. ether1 attached as a bridge port to a bridge
b. Have multiple vlans run over ether1 as part of the bridge (lets assume vlans have their own IP setup - aka not from bridge)
c. can separately assign an IP address to the interface and host a subnet on t he ether1 port all separate from the bridge and the vlans!!
 
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mkx
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Re: VLANs and address assignment

Mon Jun 21, 2021 11:09 pm

So where in original post does @Cablenut9 mention a bridge? Let's read together:

If I have some interface, like ether1, and a bunch of VLAN interfaces on it, like vlan2 and vlan3, does ether1's IP address "carry over" to the VLANs?

Nope, still no bridge ...
 
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anav
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Re: VLANs and address assignment

Tue Jun 22, 2021 3:52 am

I was extrapolating... and trying to determine how much one could stress an ethernet port.
You avoided the question, to complex a scenario??
 
Cablenut9
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Re: VLANs and address assignment

Tue Jun 22, 2021 4:15 am

I'm actually thinking of making a ROAS setup where none of the ports are on a bridge, so they're all routed and can either have the same or different addresses.
 
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mkx
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Re: VLANs and address assignment

Tue Jun 22, 2021 8:06 am

I'm not avoiding the question, I'm just trying to stay on topic. And you're extrapolating too much for your own good ;-) . But anyway:

a. ether1 attached as a bridge port to a bridge
c. can separately assign an IP address to the interface and host a subnet on t he ether1 port all separate from the bridge and the vlans!!

I thought you already absorbed the idea that bridge member port should not be used as interface? That it can cause problems? Bullet c. above is not correct. If ether1 is attached to bridge as port, then it's part of bridge L2 network and can not host separate L3 subnet. Unless you make effort using bridge filters ... but that defeats the idea of having ether1 member of bridge in the first place.

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