This article should assist engineers relate IFL or IFD index numbers seen on logs or show commands to the actual interface in question.
Sometimes when analyzing logs or viewing certain show commands, you will notice that ifl or ifd indexes are referenced in such logs. This prexifes might create confusion when reading the logs as engineer might not be familiar with what ifl or ifd really is. This article should assist is providing a guide on how to understand such indexes.
ifd refers to a physical device
ifl refers to a logical device
“ifd” is the physical interface device, where “ifl” is the logical interface usually called unit.
Logical interfaces are always related to a physical interface.
For example interfaces ge-1/2/3 would be a physical interface and while ge-1/2/3.0 would be a logical unit.
The organization hierarchy continues down with address families (iff)
as [… family inet] and addresses (ifa) as [… address 10.1.2.3/24].
nterfaces { ge-1/2/3 { /* ifd */ unit 0 { /* ifl */ family inet { /* iff */ address 10.1.2.3/24 { /* ifa */ primary; } } } } } In order to know which is the interface reference on the log you can use the following hidden commands: > show interfaces ifl-index <index> > show interfaces ifd- index <index> For example: > show interfaces ifd-index 1 Physical interface: me0, Enabled, Physical link is Up Interface index: 1, SNMP ifIndex: 33 Type: Ethernet, Link-level type: Ethernet, MTU: 1514, Speed: 100mbps Device flags : Present Running Interface flags: SNMP-Traps Link type : Full-Duplex Current address: 2c:6b:f5:8f:d7:bf, Hardware address: 2c:6b:f5:8f:d7:bf Last flapped : 2015-09-10 23:08:06 UTC (11w0d 00:45 ago) Input packets : 3528290 Output packets: 1595143 Logical interface me0.0 (Index 3) (SNMP ifIndex 34) Flags: Up SNMP-Traps Encapsulation: ENET2 Input packets : 3528290 Output packets: 1595143 Protocol inet, MTU: 1500 Flags: Is-Primary Addresses, Flags: Is-Preferred Is-Primary Destination: 172.16.202/24, Local: 172.16.202.244, Broadcast: 172.16.202.255 {master:0} > > show interfaces ifl-index 3 Logical interface me0.0 (Index 3) (SNMP ifIndex 34) Flags: Up SNMP-Traps Encapsulation: ENET2 Input packets : 3528256 Output packets: 1595117 Protocol inet, MTU: 1500 Flags: Is-Primary Addresses, Flags: Is-Preferred Is-Primary Destination: 172.16.202/24, Local: 172.16.202.244, Broadcast: 172.16.202.255 {master:0} >