Friday, August 13, 2010

Difference between Ethernet Interface(en0) and Ethernet adapter (ent0)

AIX differentiates between hardware adapters, their interfaces and protocols standards associated.

To recognize interface card AIX uses three notations:
ent, en and et.
All are different and are described below and the sake of completeness I am using 0 at the end:
ent0:
The notation ent0 is used to specify the hardware adapter. It has nothing to do with the TCP/IP address. The parameters associated with ent0 can be seen as below:
# lsattr –El ent0
It will show parameters related to card.
It shows adapter_names, alt_addr, auto_recovery, backup_adapter, hash_mode, mode, netaddr, noloss_failover, num_retries, retry_time, use_alt_addr, use_jumbo_frame.
en0:
en0 represents the interface associated with hardware adapter ent0. The notation en0 is used for Standard Ethernet(inet). The TCP/IP address is associated with this interface.
The parameters associated with en0 can be seen as below:
#lsattr –El en0
It'll shows all the parameters related with the interface en0 of the adapter ent0.
It shows alias4, alias6, arp, authority, broadcast=1500, mtu, netaddr, netaddr6, netmask, prefixlen, remmtu, rfc1323, security, state, tcp_mssdflt, tcp_nodelay, tcp_recvspace, tcp_sendspace.
Rest everything is same except mtu(Maximum Transfer Unit) value. Which is 1500 as per the standard ethernet protocol.
et0:
et0 represents the interface associated with hardware adapter ent0. The notation et0 is used for IEEE 802.3 Ethernet(inet). If you are using standard ethernet protocol then it will not have TCP/IP address.
The parameters associated with et0 can be seen as below:
#lsattr –El et0
It'll shows all the parameters related with the interface et0 of the adapter ent0.
It shows alias4, alias6, arp, authority, broadcast, mtu=1492, netaddr, netaddr6, netmask, prefixlen, remmtu, rfc1323, security, state, tcp_mssdflt, tcp_nodelay, tcp_recvspace, tcp_sendspace.
Note here as well that the MTU shown will be 1492 as per IEEE 802.3 standard. Rest all parameters will be same. Also, netaddr, netmask fields will be empty fr et0.

Are these terms interchangable or is there a difference between them? I always get confused with these terms. What does en0 and ent0 mean and the difference between these?

AIX differentiates between a network adapter and network interface:

Network adapter Represents the layer-2 device, for example, the Ethernet adapter ent0 has a MAC address, such as 06:56:C0:00:20:03

Network interface Represents the layer-3 device, for example the Ethernet interface en0 has an IP address, such as 9.3.5.195

Typically, a network interface is attached to a network adapter, for example, an Ethernet interface en0 is attached to an Ethernet adapter ent0.

There are also some network interfaces in AIX that are not attached to a network adapter, for example, the loopback interface lo0 or a Virtual IP Address (VIPA) interface, such as vi0, if defined.

4 comments:

Anonymous said...

Thanks for the explanation Satish.

Hamilton said...

I always get confused with these terms. Now i finally got it. A network interface is attached to a network adapter, for example, an Ethernet interface en0 is attached to an Ethernet adapter ent0.

Anonymous said...

Thanks Satish!

SOURADEEP CHAKRABARTI said...

Nice discussion on interface.