VLTi link is added as an implicit member of the RPM vlan. As a result, the mirrored traffic also reaches the peer VLT device effecting VLTilink's bandwidth usage.To mitigate this issue, the L2 VLT egress mask drops the duplicate packets that egress out of the VLT port. If the LAG status of the peerVLT device is OPER-UP, then the other VLT peer blocks the transmission of packets received through VLTi to its port or LAG. As a result,the destination port on the device to which the packet analyzer is connected does not receive duplicate mirrored packets.VLT Fail-over ScenarioConsider a scenario where port monitoring is configured to mirror traffic on the source port or LAG of a VLT device to a destination port onan other device on the network. A fail-over occurs when the primary VLT device fails causing the secondary VLT device to take over. At thetime of failover, the mirrored packets are dropped for some time. This time period is equivalent to the gracious VLT failover recovery time.RPM over VLT ScenariosThis section describes the restrictions that apply when you configure RPM in a VLT set up. Consider a simple VLT setup where two VLTpeers are connected using VLTi and a top-of-rack switch is connected to both the VLT peers using VLT LAGs in a ring topology. In thissetup, the following table describes the possible restrictions that apply when RPM is used to mirror traffic:Table 68. RPM over VLT ScenariosScenario RPM Restriction Recommended SolutionMirroring an Orphan Port on a VLT LAG —In this scenario, the orphan port on a VLTdevice is mirrored to the VLT LAG thatconnects a top-of-rack (TOR) switch to theVLT device. The packet analyzer isconnected to the TOR switch.The bandwidth of the VLTi link isunnecessarily used by mirrored traffic if maxrate limit value is configured in the RPMmirror session.Use ERPM session instead of RPM.Mirroring an ICL LAG to Orphan Port — Inthis scenario, the ICL LAG is mirrored to anyorphan port on the same VLT device. Thepacket analyzer is connected to the localVLT device through the orphan port.No restrictions apply. If the packet analyzer is directly connectedto the VLT device, use local Port mirroringsession instead of RPM.Mirroring an ICL LAG to the VLT LAG — Inthis scenario, the ICL LAG is mirrored to theVLT LAG on the same VLT device. Packetanalyzer is connected to the TOR.No restrictions apply. None.Mirroring VLT LAG to Orphan Port — In thisscenario, the VLT LAG is mirrored to anorphan port on the same VLT device. Thepacket analyzer is connected to the VLTdevice through the orphan port..No restrictions apply. If the packet analyzer is directly connectedto the VLT device, use local Port mirroringsession instead of RPM.Mirroring using Intermediate VLT device —In this scenario, the VLT device acts as theintermediate device in remote mirroring. TheTOR switch contains the source-RPMconfigurations that enable mirroring of theVLT lag (of the TOR switch) to any orphanport in the VLT device. The packet analyzerNo restrictions apply None.674 Port Monitoring
