Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Private MAC Address range

Dear all,

I want to configure a MAC address on my asa 5520 interface.I ask you if exist a private MAC adrress range?

Thanks & Regards,

Igor.

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Silver

Re: Private MAC Address range

Igor

While your certainly can do:

01-18-19-9e-79-cc

03-18-19-9e-79-cc

05-18-19-9e-79-cc

...

there is really not need to keep the lower part of the address the same. So you could also do:

01-01-01-01-01-01

01-02-02-02-02-02

01-03-03-03-03-03

or any pattern that makes sense to you.

HTH

Rick

5 REPLIES
Hall of Fame Super Silver

Re: Private MAC Address range

Igor

In Ethernet MAC addresses the low order bit of the first byte indicates locally administered addressing (it is sometimes referred to as the LAA bit). If it is set to 1 it indicates that this is not the burned in MAC but is an assigned MAC. So any Ethernet MAC that starts with 01 is effectively a private MAC.

HTH

Rick

New Member

Re: Private MAC Address range

Dear Rick,

thanks for your fast response.

Ok, so I will do:

This is the burned in MAC :00-18-19-9e-79-cc

the First private assigned MAC is: 01-18-19-9e-79-cc ?

The second private assigned Mac is 03-18-19-9e-79-cc ?

I have a lot of subinterfaces.

Best regards,

Igor.

Hall of Fame Super Silver

Re: Private MAC Address range

Igor

While your certainly can do:

01-18-19-9e-79-cc

03-18-19-9e-79-cc

05-18-19-9e-79-cc

...

there is really not need to keep the lower part of the address the same. So you could also do:

01-01-01-01-01-01

01-02-02-02-02-02

01-03-03-03-03-03

or any pattern that makes sense to you.

HTH

Rick

New Member

Private MAC Address range

This is incorrect answers.

Least significant bit of the first octet identifies multicast address.

Second least significant bit identifies local/global assignment.

So correct MACs shold have 'xxxxxx10' bits set in first octet, like 02, 06, 0A and so on.

Hall of Fame Super Silver

Private MAC Address range

You are correct about this (+5 for the correction) and my post was not correct about which bit to manipulate. Thank you for catching this and supplying the correct information.

HTH

Rick

5641
Views
5
Helpful
5
Replies