Command Reference Guide

SROS Command Line Interface Reference Guide Enable Mode Command Set

Technology Review

A network loopback loops data toward the network (away from the unit). A customer loopback loops data

toward the router. The router does not instigate customer-side loopbacks, only network loopbacks (remote

or local). The reason for this is that the customer interface is internal to the router. There is little use for

looping back router data on itself.

A transparent loopback is one in which the unit loops back one side (i.e., network) and also allows the

same incoming data to be passed through to the customer side. A non-transparent loopback is one which

loops back one side of the interface (network) but sends idle codes to the other side (customer). The

Secure Router OS defaults to non-transparent loopbacks. The reason for this is that sending test patterns

into the IP stack could cause unpredictable behavior. However, it is still possible for the network to send a

transparent loopback request. Such requests will be accepted.