Loopback-mode Port

Loopback-mode port means that a physical port can become a network port (ingress) and tool port (egress) to which map rules can be applied. A loopback-mode port is operated in loopback mode and avoids customers to connect a physical cable to make it operate in Loopback mode.

As soon as a loopback-mode port is configured, it is internally changed to loopback mode. This means that the link will always be UP with or without cables inserted. Traffic flows out of a loopback port (Tx direction) and loops back to it (Rx direction).

Loopback-mode ports can provide the following flexibility:

  • Support for multiple lookups on the same packet.

    - For example, Decap the tunnel and look up based on the inner header

  • Multiple egress actions on the same traffic.

    - For example, send to tool as-is and add a VLAN tag

The following image shows a visual representation of the loopback-mode port:


1. Configure Network/Tool port(s)

//Tool ports
configure terminal
interface ethernet Ethernet16/1
forward-error-correction rs
type tool
//Network ports
configure terminal
interface ethernet Ethernet12/1
forward-error-correction rs
type network

2. Configure the port as Loopback-mode

configure terminal
interface ethernet Ethernet20/1

3. Configure Flow from Network to Loopback port

configure terminal
flow flow1
network-ports Ethernet12/1
tool-ports Ethernet20/1
rule 1 permit match-all counters enable

4. Configure Flow from Loopback to Tool port

configure terminal
flow flow2
network-ports Ethernet20/1
tool-ports Ethernet16/1
rule 1 permit src-ip dest-ip counters enable

5. Verify

// verify interface
pbnoscli# show interface status 
Port              Name                            Oper    Admin   Vlan    Speed   MTU     AutoNeg 
Ethernet1/1       etp1                            down    up              100000  9100    on      
Ethernet2/1       etp2                            down    up              100000  9100    on      
Ethernet3/1       etp3                            down    up              100000  9100    on      
Ethernet4/1       etp4                            up      up              25000   9100    on      
Ethernet5/1       etp5                            up      up              25000   9100    on      
Ethernet6/1       etp6                            up      up              100000  9100    on      
Ethernet63/1      etp21                           down    up              100000  9100    on      
Ethernet64/1      etp22                           down    up              100000  9100    on      
// verify loopback-mode port
pbnoscli# show interface npb Ethernet20/1
Interface : Ethernet20/1      
Mode           : vlan-aware      
Ingress-vlan   : 22              
Egress-tagging : disable         
Loopback-mode  : enable          


Loopback-mode(i.e. Ethernet20/1) port will always be UP

// verify flow
pbnoscli# show flow summary 
Flow-Name       Rule-Id        Status      Counter-Value
flow1           1             Active          11592               
flow2           1             Active          590