Can someone explain to me why, if MAC address is an address, "...issued at the factory and do not change.", how a device can have more than one MAC address?
How Can A Device Have More Than One MAC Address?
Frank, one example: your computer has multiple NICs, e.g., you have a 100Mb/s Ethernet wired connection and a WiFi connection. Each would have its own MAC.
There are many other combinations like a server having multiple wired Ethernet connections or a laptop having WiFI and 4G connections, etc.
I should have been more specific. How can a camera have more than one MAC address?
Which cameras have more than one MAC address?
A camera with wireless and wired output would, but besides that, which specific cameras have you seen with multiple MAC addresses?
I haven't. My question is really about Question 6 on Quiz #2. Perhaps a discussion about this should be postponed until after the end date for the quiz.....
Hello Frank:
The MAC is associated with the NIC, not the device. If a device has multiple NICs (ie: Wired/WiFi interfaces, like John H mentions), two MACs are possible.
When a camera has only one NIC (like the majority do), we can use the MAC as a unique identifier for a camera. However, this is not always a guarantee, and this question enforces that point.
Does that help?
"Multiple MACs Possible but UnlikelyIf a device has multiple network interfaces, it may have more than one single MAC address. The MAC is associated with a device's network interfaces, but not the general device. In the case of cameras with multiple network connections, like a camera with both a wired ethernet port and an integrated wireless radio, the device could have more than a single MAC address.
However, since the vast majority of cameras include only a single ethernet port, the MAC address may indirectly be used to describe the entire camera."
Another example: The Sony SNT four-channel encoders have four MAC addresses, four IP addresses, but only one Ethernet port.
Dedicated micros seem to use dual Mac addressing...
I believe the DM 'IPTV' system authenticates devices by both MAC and VLAN per an access list. (This is the 'dual part'.) As such, it is a matter of network authentication (ie: Network Security) rather than pure addressing.
The entire DM IPTV approach is a little odd and a rather extreme solution (using proprietary switches) to a problem more easily and conventionally dealt with using standard access lists and port security in managed switches.
FYI: We will discuss Network Security (both simple and extreme methods like 802.1x for IP Cameras) in the Thursday class of Week #4.
Hi,
If you have a device that has 2 different kinds of network connection (for example 2 ethernet ports, or 1 ethernet port + WiFi), you will have 2 different mac adress.
It's because you have 2 different hw boards that manage each network connection, and each board has it's own mac adress.
I am currently testing a new NVR and it has two seperate ethernet connections. The MAC address on each port is different. In this case, I have two seperate devices in the same chassis that manage seperate network connection...and each port/device has it's own MAC adress.
which nvr have more than one mac address?
Seen a few, take the Hikvision range they have two NICs so two MAC addresses :)
Any NVR with multiple NICs will have multiple MAC addresses. This is increasingly common for mid to high end NVRs.
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