Dell S3048-ON, Configuration Manual

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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 VLTi
link'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 peer
VLT 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 Scenario
Consider a scenario where port monitoring is configured to mirror traffic on the source port or LAG of a VLT device to a destination port on
an other device on the network. A fail-over occurs when the primary VLT device fails causing the secondary VLT device to take over. At the
time 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 Scenarios
This section describes the restrictions that apply when you configure RPM in a VLT set up. Consider a simple VLT setup where two VLT
peers 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 this
setup, the following table describes the possible restrictions that apply when RPM is used to mirror traffic:
Table 51. RPM over VLT Scenarios
Scenario RPM Restriction Recommended Solution
Mirroring an Orphan Port on a VLT LAG —
In this scenario, the orphan port on a VLT
device is mirrored to the VLT LAG that
connects a top-of-rack (TOR) switch to the
VLT device. The packet analyzer is
connected to the TOR switch. The bandwidth of the VLTi link is
unnecessarily used by mirrored traffic if max
rate limit value is configured in the RPM
mirror session. Use ERPM session instead of RPM.
Mirroring an ICL LAG to Orphan Port — In
this scenario, the ICL LAG is mirrored to any
orphan port on the same VLT device. The
packet analyzer is connected to the local
VLT device through the orphan port. No restrictions apply. If the packet analyzer is directly connected
to the VLT device, use local Port mirroring
session instead of RPM.
Mirroring an ICL LAG to the VLT LAG — In
this scenario, the ICL LAG is mirrored to the
VLT LAG on the same VLT device. Packet
analyzer is connected to the TOR. No restrictions apply. None.
Mirroring VLT LAG to Orphan Port — In this
scenario, the VLT LAG is mirrored to an
orphan port on the same VLT device. The
packet analyzer is connected to the VLT
device through the orphan port.. No restrictions apply. If the packet analyzer is directly connected
to the VLT device, use local Port mirroring
session instead of RPM.
Mirroring using Intermediate VLT device —
In this scenario, the VLT device acts as the
intermediate device in remote mirroring. The
TOR switch contains the source-RPM
configurations that enable mirroring of the
VLT lag (of the TOR switch) to any orphan
port in the VLT device. The packet analyzer No restrictions apply None.
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