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Occasional Contributor I

active-gateway mac address range for 8325 CX os

active-gateway ip 10.10.10.10 mac 00:00:00:00:01:09

 

can anyone help me with the range of the virtual mac-address.

 

is there a range or how is it generally defined ?

 

 

Aruba Employee

Re: active-gateway mac address range for 8325 CX os

You basically utilize an unused MAC address on that subnet for the active gateway IP.

Leaf2(config)# int vlan 11
Leaf2(config-if-vlan)#ip address 10.1.11.2/24
Leaf2(config-if-vlan)# active-gateway ip 10.1.11.1 mac 0:0:0:0:0:11:1

 

Leaf2(config)# int vlan 12
Leaf2(config-if-vlan)#ip address 10.1.12.2/24
Leaf2(config-if-vlan)# active-gateway ip 10.1.12.1 mac 0:0:0:0:0:12:1

 

In fact, since the MAC is locally significant, you can use the same virtual MAC for different subnets if desired.

New Contributor

Re: active-gateway mac address range for 8325 CX os

Hello!

 

I find it a little unfortunate that Aruba is recommending specifically 00:00:00 as a prefix for these MAC addresses, and not providing any guidance for properly selecting MAC addresses.

 

In any system where you assign your own MAC addresses, you should make sure to choose the first byte carefully, so that you get a MAC address that is:

 

- Unicast address (bit 0 of the first byte is set to 0).

- Locally administered (bit 1 in the first byte is set to 1)

 

An example of a suitable MAC address for the active-gateway on VSX would therefore be 02:00:00:00:00:01

 

Any time you're using locally administered MAC addresses you need to take care not to create MAC conflicts with other parties also configuring locally administered MAC addresses on your network.

 

The problem is that the examples used in Aruba's documentation (and also in this thread) mostly start with 00, which would technically make them globally administered. The OUI 00:00:00 is not assigned to Aruba or HPE. It might be assigned to Xerox, but what I could find is unclear.

 

The consequence of locally configuring a globally administered MAC address is that another device you connect to your network might come with the same MAC address as you've locally configured straight from the factory, and cause some strange network issues when plugged in. The risk is extremely small for one particular network, especially for the OUI prefix 00:00:00, but there's no reason to ignore Internet standards in general, especially when doing so provides no benefit.

 

In addition, if you make your first byte odd (for example starting your address with 01, so that bit 0 is set to 1), you're flagging the address as a Multicast address. I have no idea how that might break your network, just that it probably will break something somewhere. :-)

 

I hope Aruba can update their documentation to reflect this, ideally providing some guidance on selecting your own MAC address, or at the very least not using globally unique MAC addresses in their examples.

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