In Ubuntu 16+, for a network interface “ens192”, where does the “192” come from?
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We have dozens of virtual machines in several data centers around the world. When upgrading an Ubuntu VM from 14 to 16 (as a step toward upgrading them to Ubuntu 18), the network interface names change. I am aware of this, and I know why they change, so that is not my question. My question is where does the number (the 33 in ens33, the 192 in ens192, etc.) come from? I have read many StackExchange questions and answers about what to do to get the server working: that is not the problem. What I want to know is how to predict what the ens### will be before the server is upgraded to Ubuntu 16. I have looked at lshw and lspci, and I can't see any reason why these numbers are chosen.
Please: where does the 192 (or 33, or anything else) come from?
networking interface
asked Dec 1 at 20:49
user3158465
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We have dozens of virtual machines in several data centers around the world. When upgrading an Ubuntu VM from 14 to 16 (as a step toward upgrading them to Ubuntu 18), the network interface names change. I am aware of this, and I know why they change, so that is not my question. My question is where does the number (the 33 in ens33, the 192 in ens192, etc.) come from? I have read many StackExchange questions and answers about what to do to get the server working: that is not the problem. What I want to know is how to predict what the ens### will be before the server is upgraded to Ubuntu 16. I have looked at lshw and lspci, and I can't see any reason why these numbers are chosen.
Please: where does the 192 (or 33, or anything else) come from?
networking interface
asked Dec 1 at 20:49
user3158465
1
New contributor
user3158465 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
The format is <device name><slot #><port #>. It was a dumb idea to standardize network names. For example ens01p01 means the ethernet network port on slot #1 port #1.
– heynnema
Dec 1 at 21:32
In oyr environment, they are always in the form ens### (or ens##). How would I know what that ### (or ##) is going to be before the system removed eth0 and creates ens192?
– user3158465
Dec 2 at 1:06
I don't think you can. There might be similarities when using similar motherboards with similar ports. I can't say for sure. You can always add the kernel parameternet.ifnames=0which keeps the old names... eth0, etc.
– heynnema
Dec 2 at 3:00
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
We have dozens of virtual machines in several data centers around the world. When upgrading an Ubuntu VM from 14 to 16 (as a step toward upgrading them to Ubuntu 18), the network interface names change. I am aware of this, and I know why they change, so that is not my question. My question is where does the number (the 33 in ens33, the 192 in ens192, etc.) come from? I have read many StackExchange questions and answers about what to do to get the server working: that is not the problem. What I want to know is how to predict what the ens### will be before the server is upgraded to Ubuntu 16. I have looked at lshw and lspci, and I can't see any reason why these numbers are chosen.
Please: where does the 192 (or 33, or anything else) come from?
networking interface
asked Dec 1 at 20:49
user3158465
1
New contributor
user3158465 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
We have dozens of virtual machines in several data centers around the world. When upgrading an Ubuntu VM from 14 to 16 (as a step toward upgrading them to Ubuntu 18), the network interface names change. I am aware of this, and I know why they change, so that is not my question. My question is where does the number (the 33 in ens33, the 192 in ens192, etc.) come from? I have read many StackExchange questions and answers about what to do to get the server working: that is not the problem. What I want to know is how to predict what the ens### will be before the server is upgraded to Ubuntu 16. I have looked at lshw and lspci, and I can't see any reason why these numbers are chosen.
Please: where does the 192 (or 33, or anything else) come from?
networking interface
networking interface
asked Dec 1 at 20:49
user3158465
1
New contributor
user3158465 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked Dec 1 at 20:49
user3158465
1
New contributor
user3158465 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked Dec 1 at 20:49
user3158465
1
New contributor
user3158465 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked Dec 1 at 20:49
user3158465
1
asked Dec 1 at 20:49
user3158465
1
1
New contributor
user3158465 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
user3158465 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
user3158465 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
The format is <device name><slot #><port #>. It was a dumb idea to standardize network names. For example ens01p01 means the ethernet network port on slot #1 port #1.
– heynnema
Dec 1 at 21:32
In oyr environment, they are always in the form ens### (or ens##). How would I know what that ### (or ##) is going to be before the system removed eth0 and creates ens192?
– user3158465
Dec 2 at 1:06
I don't think you can. There might be similarities when using similar motherboards with similar ports. I can't say for sure. You can always add the kernel parameternet.ifnames=0which keeps the old names... eth0, etc.
– heynnema
Dec 2 at 3:00
add a comment |
1
The format is <device name><slot #><port #>. It was a dumb idea to standardize network names. For example ens01p01 means the ethernet network port on slot #1 port #1.
– heynnema
Dec 1 at 21:32
In oyr environment, they are always in the form ens### (or ens##). How would I know what that ### (or ##) is going to be before the system removed eth0 and creates ens192?
– user3158465
Dec 2 at 1:06
I don't think you can. There might be similarities when using similar motherboards with similar ports. I can't say for sure. You can always add the kernel parameternet.ifnames=0which keeps the old names... eth0, etc.
– heynnema
Dec 2 at 3:00
1
1
The format is <device name><slot #><port #>. It was a dumb idea to standardize network names. For example ens01p01 means the ethernet network port on slot #1 port #1.
– heynnema
Dec 1 at 21:32
The format is <device name><slot #><port #>. It was a dumb idea to standardize network names. For example ens01p01 means the ethernet network port on slot #1 port #1.
– heynnema
Dec 1 at 21:32
In oyr environment, they are always in the form ens### (or ens##). How would I know what that ### (or ##) is going to be before the system removed eth0 and creates ens192?
– user3158465
Dec 2 at 1:06
In oyr environment, they are always in the form ens### (or ens##). How would I know what that ### (or ##) is going to be before the system removed eth0 and creates ens192?
– user3158465
Dec 2 at 1:06
I don't think you can. There might be similarities when using similar motherboards with similar ports. I can't say for sure. You can always add the kernel parameter
net.ifnames=0 which keeps the old names... eth0, etc.– heynnema
Dec 2 at 3:00
I don't think you can. There might be similarities when using similar motherboards with similar ports. I can't say for sure. You can always add the kernel parameter
net.ifnames=0 which keeps the old names... eth0, etc.– heynnema
Dec 2 at 3:00
add a comment |
1 Answer
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0
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While I don't know why they are the ensXX format, if you want to disable them to have consistent naming across servers and get the legacy ethX, you'll want to set the net.ifnames=0 biosdevname=0 kernel boot arguments in GRUB or your bootloader in general.
answered Dec 1 at 21:08
JavaProphet
1285
I know how to do that, and I appreciate the information. However, my questions is: How would I know what that ### (or ##) is going to be before the system removes eth0 and creates ens###?
– user3158465
Dec 2 at 1:07
@user3158465 From my experience, it seems to allocate them incrementally, and never reassigns them to another NIC (perhaps based on MAC address). In that, it provides consistency of configuration across swapped NICs, but not the same configuration for all NICs. This is just a guess though.
– JavaProphet
Dec 2 at 5:15
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
0
down vote
While I don't know why they are the ensXX format, if you want to disable them to have consistent naming across servers and get the legacy ethX, you'll want to set the net.ifnames=0 biosdevname=0 kernel boot arguments in GRUB or your bootloader in general.
answered Dec 1 at 21:08
JavaProphet
1285
I know how to do that, and I appreciate the information. However, my questions is: How would I know what that ### (or ##) is going to be before the system removes eth0 and creates ens###?
– user3158465
Dec 2 at 1:07
@user3158465 From my experience, it seems to allocate them incrementally, and never reassigns them to another NIC (perhaps based on MAC address). In that, it provides consistency of configuration across swapped NICs, but not the same configuration for all NICs. This is just a guess though.
– JavaProphet
Dec 2 at 5:15
add a comment |
up vote
0
down vote
While I don't know why they are the ensXX format, if you want to disable them to have consistent naming across servers and get the legacy ethX, you'll want to set the net.ifnames=0 biosdevname=0 kernel boot arguments in GRUB or your bootloader in general.
answered Dec 1 at 21:08
JavaProphet
1285
I know how to do that, and I appreciate the information. However, my questions is: How would I know what that ### (or ##) is going to be before the system removes eth0 and creates ens###?
– user3158465
Dec 2 at 1:07
@user3158465 From my experience, it seems to allocate them incrementally, and never reassigns them to another NIC (perhaps based on MAC address). In that, it provides consistency of configuration across swapped NICs, but not the same configuration for all NICs. This is just a guess though.
– JavaProphet
Dec 2 at 5:15
add a comment |
up vote
0
down vote
up vote
0
down vote
While I don't know why they are the ensXX format, if you want to disable them to have consistent naming across servers and get the legacy ethX, you'll want to set the net.ifnames=0 biosdevname=0 kernel boot arguments in GRUB or your bootloader in general.
answered Dec 1 at 21:08
JavaProphet
1285
While I don't know why they are the ensXX format, if you want to disable them to have consistent naming across servers and get the legacy ethX, you'll want to set the net.ifnames=0 biosdevname=0 kernel boot arguments in GRUB or your bootloader in general.
answered Dec 1 at 21:08
JavaProphet
1285
answered Dec 1 at 21:08
JavaProphet
1285
answered Dec 1 at 21:08
JavaProphet
1285
answered Dec 1 at 21:08
JavaProphet
1285
1285
I know how to do that, and I appreciate the information. However, my questions is: How would I know what that ### (or ##) is going to be before the system removes eth0 and creates ens###?
– user3158465
Dec 2 at 1:07
@user3158465 From my experience, it seems to allocate them incrementally, and never reassigns them to another NIC (perhaps based on MAC address). In that, it provides consistency of configuration across swapped NICs, but not the same configuration for all NICs. This is just a guess though.
– JavaProphet
Dec 2 at 5:15
add a comment |
I know how to do that, and I appreciate the information. However, my questions is: How would I know what that ### (or ##) is going to be before the system removes eth0 and creates ens###?
– user3158465
Dec 2 at 1:07
@user3158465 From my experience, it seems to allocate them incrementally, and never reassigns them to another NIC (perhaps based on MAC address). In that, it provides consistency of configuration across swapped NICs, but not the same configuration for all NICs. This is just a guess though.
– JavaProphet
Dec 2 at 5:15
I know how to do that, and I appreciate the information. However, my questions is: How would I know what that ### (or ##) is going to be before the system removes eth0 and creates ens###?
– user3158465
Dec 2 at 1:07
I know how to do that, and I appreciate the information. However, my questions is: How would I know what that ### (or ##) is going to be before the system removes eth0 and creates ens###?
– user3158465
Dec 2 at 1:07
@user3158465 From my experience, it seems to allocate them incrementally, and never reassigns them to another NIC (perhaps based on MAC address). In that, it provides consistency of configuration across swapped NICs, but not the same configuration for all NICs. This is just a guess though.
– JavaProphet
Dec 2 at 5:15
@user3158465 From my experience, it seems to allocate them incrementally, and never reassigns them to another NIC (perhaps based on MAC address). In that, it provides consistency of configuration across swapped NICs, but not the same configuration for all NICs. This is just a guess though.
– JavaProphet
Dec 2 at 5:15
add a comment |
user3158465 is a new contributor. Be nice, and check out our Code of Conduct.
user3158465 is a new contributor. Be nice, and check out our Code of Conduct.
user3158465 is a new contributor. Be nice, and check out our Code of Conduct.
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1
The format is <device name><slot #><port #>. It was a dumb idea to standardize network names. For example ens01p01 means the ethernet network port on slot #1 port #1.
– heynnema
Dec 1 at 21:32
In oyr environment, they are always in the form ens### (or ens##). How would I know what that ### (or ##) is going to be before the system removed eth0 and creates ens192?
– user3158465
Dec 2 at 1:06
I don't think you can. There might be similarities when using similar motherboards with similar ports. I can't say for sure. You can always add the kernel parameter
net.ifnames=0which keeps the old names... eth0, etc.– heynnema
Dec 2 at 3:00