Replication of mirrored packets can affect performance and should be used carefully. The 7705 SAR, making use of network processor based forwarding, allows efficient mirror service scaling and, at the same time, allows a large amount of data to be mirrored with minimal performance impact. When a mirror destination is configured, the packet slice option can truncate mirrored packets to the destination, which minimizes replication and tunneling overhead.
When a packet at port ingress is mirrored, one extra buffer per packet is used. For more information, see the ‟Buffer Allocation for Multicast Traffic” section in the 7705 SAR Quality of Service Guide.