Port State and Operational State

There are two port attributes that are related and similar but have slightly different meanings: Port State and Operational State (or Operational Status).

The following descriptions are based on normal individual ports. Many of the same concepts apply to other objects that are modeled as ports in the router such as PPP/IMA/MLFR multilink bundles or APS groups but the show output descriptions for these objects should be consulted for the details.

The behavior of Port State and Operational State are different for a port with link protocols configured (Eth OAM, Eth CFM or LACP for Ethernet ports, LCP for PPP/POS ports). A port with link protocols configured only transitions to the Up Port State when the physical link is up and all the configured protocols are up. A port with no link protocols configured transitions from Down to Link Up and then to Up immediately after the physical link layer is up.

The linkDown and linkUp log events (events 2004 and 2005 in the SNMP application group) are associated with transitions of the port Operational State. Note that these events map to the RFC 2863, The Interfaces Group MIB, (which obsoletes RFC 2233, The Interfaces Group MIB using SMIv2) linkDown and linkUp traps as mentioned in the SNMPv2-MIB.

An Operational State of Up indicates that the port is ready to transmit service traffic (the port is physically up and any configured link protocols are up). The relationship between port Operational State and Port State is shown in Table 1:

Table 1. Relationship of Port State and Oper State

Operational State (Oper State or Oper Status) (as displayed in ‟show port x/y/z”)

Port State (as displayed in the show port summary)

For ports that have no link layer protocols configured

For ports that have link layer protocols configured (PPP, LACP, 802.3ah EFM, 802.1ag Eth-CFM)

Up

Up

Up

Link Up (indicates the physical link is ready)

Up

Down

Down

Down

Down