How is that the MAC address (BIA : Burn -in -Address) not yet exhausted?

[grapevine]

How is that the MAC address (BIA : Burn -in -Address) not yet exhausted? IPV4 is exhausted and we are moving to IPV6!

[daniel.dib]

MAC addresses are 48 bits long. That is 65536 times the IPv4 space. IP addresses need to be globally unique while MAC addresses only need to be unique on their local LAN segment (LAN/VLAN).

Here is a good link explaining it more in detail:

http://blog.michaelfmcnamara.com/2013/03/are-we-running-out-of-mac-addresses/

There is also a link there that suggests some edits to the 24-bit OUI assignments:

http://www.ietf.org/proceedings/86/slides/slides-86-iab-techplenary-5

Daniel Dib

CCIE #37149

[grapevine]

Ok, What would happen if two devices/ PCs on the same network had same MAC address and different IP addresses?

[daniel.dib]

Frames could get erroneously delivered because switches only look at the destination MAC address. So if PC1 has MAC1 and PC2 has MAC1. PC3 is sending traffic towards PC1 but the frames get delivered to PC2 instead.

There could also be MAC address learning flapping because the switch sees the same MAC on different ports and does not know what to do with it.

Daniel Dib
CCIE #37149