topic Re: Management addresses are not available in Switches, Hubs, and Modems

Management addresses are not available

fghfgcdxfg — Tue, 05 Jan 2021 23:43:11 GMT

I think it is not a problem, more missing knowledge.

My situation

I have a core switch with some vlans. We are using default vlan 1 as management vlan. vlan 1 is untagged on every uplinkport to every access switch.

My config

core switch uplink: untagged: vlan 1 - tagged: vlan 10, 11, 12

access-switch: untagged: vlan 1 - tagged: vlan 10, 11, 12 - management ip is active on every vlan (DHCP)

The access-switch has 4 ip-addresses (one per vlan), i can connect to every single ip-address until i remove the untagged vlan 1 on one site of the connection. in that case, no ip-adress is reachable. all clients behind the access-switch are still online, only the management-addresses from the switch are not longer available. When i set vlan 1 untagged again, all 4 addresses are directly available.

Im wondering that all addresses are not available if i remove the untagged vlan 1 and use only tagged vlans on the uplinkport. I would expect that the other addresses are still online.

BTW: if i reboot the access-switch, it still receives on all 3 tagged vlans an address. My client is connected to the core switch.

Is that normal? Can someone please explain to me why this works like that?

Re: Management addresses are not available

Emil_G — Thu, 07 Jan 2021 08:17:15 GMT

Hello,

I think more information would be helpful to better understand the configuration.

First of all you are not mentioning the switch model. Assuming that it is ArubaOS resp ProCurve switch but please provide exact model and firmware revision.

VLAN 1 is the management VLAN. Did you specify it as management VLAN with the CLI command management-vlan like this.

HP Switch (config)#: management-vlan 1

If I understand correctly both the core switch and the access switch have IPs in all VLANs, 1, 10, 11 and 12. Which switch is configured to do the inter VLAN routing? The core switch? Or the access switch is also routing? (show ip will show you if IP routing is enabled or not)

If the access switch is not routing what is purpose of having IP addresses in all the VLANs. This is a bit unusual.

Depending on the answer of the previous question, the access switch should have an ip default-gateway or a static default route. ( show ip will show you the default gateway, show ip route will show you all the routes). Please provide information which VLAN is the outbound interface for the default gateway/route!

In which VLAN is located the PC from which you are trying to reach the switch IP addresses? Is it in VLAN 1, 10, 11, 12? Or it is some VLAN/ip subnet which is not directly connected to the switches?

Re: Management addresses are not available

Emil_G — Thu, 21 Jan 2021 08:51:18 GMT

Hello @fghfgcdxfg

WIthout the information I asked for it would be difficult to give you a correct answer. I suspect that access switches are configured without IP routing and using a default-gateway in VLAN 1. The switch will use its default gateway for return traffic to hosts which are not in the management VLAN or any of the connected VLANs. If VLAN 1 is down the default-gateway is also not reachable.

Another possible scenario is that you have configured "management-vlan 1" which this command the switch restricts management access only to ports member of this VLAN. If you remove this VLAN the switch doesnt have ports which are members of the management VLAN and will block management access.

Please, if you still have the same issue, provide answers to my questions. If you were able to identify what is causing it and have fixed it, please share the solution for the benefit of the community users.