Management and Configuration Guide K/KA/KB.15.15

on an HP switch uses IPv4 to encapsulate mirrored traffic sent to a remote endpoint switch, the
intermediate switches and routers in a layer 2/3 domain can be from any vendor if they support
IPv4.
The following restrictions apply to remote endpoint switches and intermediate devices in a network
configured for traffic mirroring:
• The exit port for a mirroring destination must be an individual port and not a trunk, mesh, or
VLAN interface.
• A switch mirrors traffic on static trunks, but not on dynamic LACP trunks.
• A switch mirrors traffic at line rate. When mirroring multiple interfaces in networks with
high-traffic levels, it is possible to copy more traffic to a mirroring destination than the link
supports. However, some mirrored traffic may not reach the destination. If you are mirroring
a high-traffic volume, you can reduce the risk of oversubscribing a single exit port by:
• Directing traffic from different session sources to multiple exit ports.
• Configuring an exit port with a higher bandwidth than the monitored source port.
Migration to release K.12.xx
On a switch that is running a software release earlier than K.12.xx with one or more mirroring
sessions configured, when you download and boot release K.12.xx, the existing mirroring
configurations are managed as follows:
• A legacy mirroring configuration on a port or VLAN interface maps to session 1.
• Traffic-selection criteria for session 1 is set to both; both inbound and outbound traffic (traffic
entering and leaving the switch) on the configured interface is selected for mirroring.
• In a legacy mirroring configuration, a local exit port is applied to session 1.
Booting from software versions earlier than K.12.xx
If it is necessary to boot the switch from a legacy (pre-K.12.xx) software version after using version
K.12.xx or greater to configure mirroring, remove mirroring from the configuration before booting
with the earlier software.
Maximum supported frame size
The IPv4 encapsulation of mirrored traffic adds a 54-byte header to each mirrored frame. If a
resulting frame exceeds the MTU allowed in the path from the mirroring source to the mirroring
destination, the frame is dropped, unless the optional [truncation] parameter is set in the
mirror command.
Frame truncation
Mirroring does not truncate frames unless the truncation parameter in the mirror command
is set. If that parameter is not set, oversized mirroring frames are dropped. Also, remote mirroring
does not allow downstream devices in a mirroring path to fragment mirrored frames.
Migration to release K.14.01 or greater
NOTE: If a switch is running software release K.12.xx, you must first upgrade to release K.13.xx
before migrating the switch to release K.14.01 or greater.
When you download and boot software release K.14.01 or greater on a switch that is running
release K.13.xx and has one or more mirroring sessions configured, an ACL-based mirroring
configuration on a port or VLAN interface is mapped to a class and policy configuration based
on the ACL.
346 Monitoring and Analyzing Switch Operation