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
// 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#
