DCE AP9465 - 3rd MAC Address discovered from Gb1

[tjlaw]

Dear Community, 

I have received a complaint from our end-user recently:

They are using Aruba access switch and with ClearPass authentication :

The access first detected the mac address is d4:xx:xx:xx:eb:e1 (The MAC address of GB2 is d4:xx:xx:xx:eb:e0) and not the d4:xx:xx:xx:eb:df (MAC address of GB1) that is showed on the DCE.

The first mac address will go to time-out after a day, after that, the DCE IP address will not reachable due to the policy that only authorized MAC address is allowed to connect. After DCE reboots, it happens that the DCE connection shows the first mac address again, which is d4:xx:xx:xx:eb:e1

Does anyone come across this issue before? 

BR, 

TJ

[Shaun]

Hi TJ,

Some questions, and an educated guess ..

• Is this a new install, and has it been configured yet?
• Can they reach the server at the IP address that's been configured, and which mac address is answering that IP?
• Has a management interface (ipmi/idrac/etc) been abled on that server?
• Would they be willing to perform a network capture of Gb1 from a powered off state to the first time they access that IP?  (This would need to be done with, eg port mirroring at the switch, as the DCE can't capture itself until the OS is up)

My speculation is that a management interface is active on Gb1.  On larger servers idrac etc have their own ethernet port - but on servers without a dedicated port, they share the first ethernet port.  And since the management controller will be raised earlier in the boot than the OS is, this may be the first address their switch is capturing.  A packet capture (at the switch) would be very useful in proving what's occurring on this interface before the OS starts using d4:xx:xx:xx:eb:df.

[tjlaw]

Hi Shaun, 

- This is an old configuration > 5 years

- I will ask users which mac address is answering the IP when they access the system. Also, if they are willing to do a network capture on Gb1 later. 

- No separate management interface. It could be using Gb1 as Idrac port as you mentioned. 

Let me forward the information to the users. I guess you hit the key point where the IDRAC might be detected during boot up. 

Thank you and Best Regards, 

TJ. 

[Anonymous user]

Hello, @Shaun 

As discussed in detail in Chapter 5, “Number Systems,” in networking, IPv4 addresses are represented using the decimal (base 10) number system and the binary (base 2) number system. IPv6 addresses and Ethernet addresses are represented using the hexadecimal (base 16) number system. To understand hexadecimal, you must first be very familiar with binary and decimal.

The hexadecimal numbering system uses the numbers 0 to 9 and the letters A to F.

An Ethernet MAC address consists of a 48-bit binary value. Hexadecimal is used to identify an Ethernet address because a single hexadecimal digit represents 4 binary bits. Therefore, a 48-bit Ethernet MAC address can be expressed using only 12 hexadecimal values.

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