Consistent Network Device Naming: Difference between revisions

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{{Short description|Convention for naming Ethernet adapters in Linux}}

'''Consistent Network Device Naming''' is a convention for naming [[Ethernet adapter]]s in [[Linux]].

It was created around 2009 to replace the old {{Mono|ethX}} naming scheme that caused problems on [[Multihoming|multihomed]] machines because the [[network interface controller]]s (NICs) would be named based on the order in which they were found by the kernel as it booted. Removing existing or adding new interfaces could cause the previously added ones to change names.<ref>{{Cite web |title= Network Device Naming mechanism and policy |date= October 9, 2009 |author= Matt Domsch |work= LWN |publisher= Eklektix, Inc |url= https://lwn.net/Articles/356900/ |accessdate= May 27, 2013 }}</ref> An ECREngineering Change Request was submitted to the [[ PCI-SIG | PCI SIG ]] [[firmware]] group on how system firmware can provide device naming to operating systems via the ACPI interface.<ref>{{Cite web |url=https://pcisig.com/sites/default/files/specification_documents/ECR_Slot_Naming-10.pdf |title=Archived copy |access-date=2017-02-22 |archive-url=https://web.archive.org/web/20170106042937/https://pcisig.com/sites/default/files/specification_documents/ECR_Slot_Naming-10.pdf |archive-date=2017-01-06 |url-status=dead }}</ref>

__TOC__

==Scheme (Biosdevname)==

The new naming scheme is:<ref name="digit" />

* {{Mono|em[''1–N'']}} for on-board (embedded) NICs (# matches chassis labels)

* {{Mono|p<''slot_number''>p<''port_number''>}} for cards in [[Peripheral Component Interconnect|PCI]] slots, ports starting at 1 (not zero)

* {{Mono|NPAR}} and {{Mono|SR-IOV}} devices add a suffix of {{Mono|_<vf>}}, from 0..N depending on the number of Partitions or Virtual Functions exposed on each port

* Other Linux conventions, such as {{Mono|.<vlan>}} and {{Mono|:<alias>}} suffixes remain unchanged and are still applicable<ref name="red">{{Cite web |url= http://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/appe-Consistent_Network_Device_Naming.html |work= Red Hat Enterprise Linux 6 documentation |title= Appendix A. Consistent Network Device Naming |accessdate= May 27, 2013 }}</ref>

==Adoption==

The convention was implemented for [[Dell]] in a module called {{Mono|biosdevname}}.<ref name="digit">{{Cite web |title= Fedora 15 Changing The Network Device Naming Scheme |work= Digitizer Linux News |url= http://digitizor.com/2011/01/25/fedora-15-network-device-naming/ |date= January 25, 2011 |accessdate= May 27, 2013 }}</ref>

Among the first major [[Linux distribution]]s to adopt the module were [[List of Fedora versions#Fedora 15|Fedora 15]] in May 2011<ref name="esecurityplanet">{{Cite web |title= Fedora 15 boosts Linux security |url= http://www.esecurityplanet.com/news/article.php/3934151/Fedora-15-Boosts-Linux-Security.html/ |work= eSecurity Planet |author= Sean Michael Kerner |date= May 20, 2011 |accessdate= May 27, 2013 |url-status= dead |archiveurl= https://archive.istoday/20130122231054/http://www.esecurityplanet.com/news/article.php/3934151/Fedora-15-Boosts-Linux-Security.html/ |archivedate= January 22, 2013 }}</ref><ref>{{Cite news |author= Joe Brockmeier |title= Breaking a few eggs: Fedora 15 changes network device naming. Fedora 15 pioneering consistent network device naming |work= Network World |date= January 24, 2011 |url= http://www.networkworld.com/community/fedora-15-changes-network-device-naming }}</ref> and [[Red Hat Enterprise Linux]] version 6.1.<ref name="red">{{Cite web |url= http://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/appe-Consistent_Network_Device_Naming.html |work= Red Hat Enterprise Linux 6 documentation |title= Appendix A. Consistent Network Device Naming |accessdate= May 27, 2013 }}</ref><ref name="dell">{{Cite web |url= http://linux.dell.com/files/whitepapers/consistent_network_device_naming_in_linux.pdf |date= July 2012 |author= Narendra K |title= Consistent Network Device Naming in Linux |publisher= [[Dell]] Linux Engineering division |accessdate= May 27, 2013 }}</ref> It was also released in [[SUSE Linux Enterprise Server]] 11 Service Pack 2 in February 2012.<ref name="dell" /> The newer [[Dell PowerEdge]] and [[Dell Precision]] models support the new names.<ref name="dell" />

An [[open-source license|open-source]] implementation is available, based on the [[udev]] mechanism now present in [[systemd]].<ref>{{Cite web |title= Biosdevname - Consistent Network Device Naming |url= http://linux.dell.com/biosdevname/ |accessdate= May 27, 2013 }}</ref><ref>{{Cite web |title= Consistent Network Device Naming |work= Project web site |publisher= Fedora |url= https://fedoraproject.org/wiki/Features/ConsistentNetworkDeviceNaming |author= Matt Domsch and Jordan Hargrave |accessdate= May 27, 2013 }}</ref>. Red Hat Enterprise Linux 7 started using [[systemd]] for networking.<ref>{{Cite web |url=http://en.community.dell.com/techcenter/b/techcenter/archive/2014/08/07/understanding-network-persistent-device-naming-in-red-hat-enterprise-linux-7 |title=ArchivedUnderstanding copynetwork persistent device naming in Red Hat Enterprise Linux 7 |access-date=2017-03-28 |archive-url=https://web.archive.org/web/20170328212000/http://en.community.dell.com/techcenter/b/techcenter/archive/2014/08/07/understanding-network-persistent-device-naming-in-red-hat-enterprise-linux-7 |archive-date=2017-03-28 |url-status=dead }}</ref>

==Device naming rules==

* Onboard interfaces at firmware index numbers {{Mono|eno[1-N]}}

* Interfaces at [[PCI Express]] hotplug slot numbers {{Mono|ens[1-N]}}

* Adapters in the specified PCI slot, with slot index number on the adapter {{Mono|enp<''PCI slot''>s<''card index no''>}}

* If firmware information is invalid or rules are disabled, use traditional {{Mono|eth[0-N]}}<ref>