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:

Configuration:
1. Configure Network/Tool port(s)
//Tool ports
configure terminal
interface ethernet Ethernet16/1
forward-error-correction rs
type tool
end
//Network ports
configure terminal
interface ethernet Ethernet12/1
forward-error-correction rs
type network
end
2. Configure the port as Loopback-mode
configure terminal
interface ethernet Ethernet20/1
loopback-mode
end
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
end
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 1.1.1.1/32 dest-ip 5.5.5.5/32 counters enable
end
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
pbnoscli#
// 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
pbnoscli#
// verify flow
pbnoscli# show flow summary
Flow-Name Rule-Id Status Counter-Value
=========================================================
flow1 1 Active 11592
flow2 1 Active 590
pbnoscli#
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