To assist in troubleshooting complex operational problems, certain packets may need to be examined as they traverse the network. One way to accomplish this is with an overlay of network analyzers established at multiple PoPs, together with skilled technicians to operate them to decode the data provided. This method of traffic mirroring often requires setting up complex filters in multiple switches or routers. These, at best, are only able to mirror from one port to another on the same device.
Nokia support for port mirroring on the 7705 SAR extends and integrates these capabilities into the network and provides significant operational benefits. Each router can mirror packets to any Ethernet interface destination point in the network.
This capability also extends beyond troubleshooting services. Telephone companies have the ability to obtain itemized calling records and wiretaps where legally required by investigating authorities. The process can be complex and costly to carry out on data networks. Service mirroring simplifies these via mirroring of the SAP port, and reduces costs through centralization of analysis tools and skilled technicians.
Original packets are forwarded while a copy is sent out the mirrored port to the mirroring (destination) port. Mirroring allows an operator to see the actual traffic on a port with a sniffer sitting in a central location. In many cases, this reduces the need for a separate, costly overlay sniffer network.
The mirrored frame size that is to be transmitted to the mirror destination can be explicitly configured by using slicing features. This enables mirroring of only the parts needed for analysis while minimizing network resource usage. For example, only the headers can be copied for analysis, protecting the integrity and security of customer data, or conversely, copying the full packet, including customer data.