HP AE370A - Brocade 4Gb SAN Switch 4/12, Administrator'S Manual

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Fabric OS 5.2.x administrator guide 303
How port mirroring works
Port mirroring reroutes the data frames between two devices to the mirror port. Rerouting introduces latency
for the data flow. The latency depends on the location of the mirror port.
For a given port, the traffic received from the point of view of the switch can be captured before leaving this
ASIC. Each user port is connected to an ASIC port. The user port's ingress traffic is routed to another user
port on this chip, uplinks to the core switch, or E_Ports to remote domains. Mirroring is used on user ports,
uplink ports (C_Ports), or E_Ports to capture the received traffic.
The user port's destination to source traffic can come from any of the E_Ports or user ports, either on the the
same chip or a different chip.
When the destination port is on a different CP or is a remote switch port, port mirroring installs ingress
(traffic received) filters on the C_Ports. If the destination port is on the same ASIC, an egress (traffic sent)
filter is installed on the source port.
A port configured as a mirror port is configured so that the transmitter is looped back to the receiver. In
addition, the transmit traffic is sent out of the transmit port. You could connect an analyzer to this port to
collect all the traffic exiting this port. The traffic looped back will then be routed to the final destination.
Traffic received externally from this port does not affect loopback traffic.
The performance server daemon (psd) maintains the port mirroring database, which contains the source
identifier, destination identifier, and a mirror port. Adding a new mirror connection adds the connection to
the database, where the information is saved. Deleting the connection removes the mirror connection from
the database.
F_Port Connection —A port mirror connection containing both the source identifier and destination
identifier on the same chip is called a “local chip connection.” In this type of connection, only two ports
are involved to capture the sent and received traffic. The destination port mirrors the received (from the
switch’s point of view) traffic.
• Traffic is received at the source port and the switch routes these frames to the destination port.
• The destination port has a port mirror, which redirects matching frames to the mirror port.
• The mirror port then routes those frames it receives back to the destination port.
FC_Port Connection —A port mirror connection between two F_Ports on different CPs but in the same
switch, as in core-edge platforms. If one port is sending traffic to another port on a different chip, the port
must send the traffic to the core to reach the edge ports located on another chip.
• Traffic is received at the source port destined to another port on a different chip. The frame is routed to
one of the C_Ports connected to the core.
• All C_Ports have a port mirror filter to redirect those frames that match the filter to the mirror port.
• 3.The mirror port then routes those frames it receives back to a C_Port.
FCE_Port Connection —Port mirror connections on which the source identifier on the local switch and
destination identifier is on a different switch is called an FCE_Port connection. In this type of connection,
the source port, all the E-ports located on the same chip as the source port and all C_Ports located on the
source chip are involved with this connection type. In addition, the C_Ports on other blades that have
E_Ports are involved in this type of connection too.
The received traffic can be sent to any E_Port, regardless of whether the port is on the same or another
chip. The port mirrors the received traffic on all C_Ports and all E_Ports on that source identifier's chip.
• Traffic is received at the source port destined to a remote port. The switch routes these frames to either a
local E+Ports on this chip or to the C_Ports to reach another E-ports on a different blade.
• The C_Ports and E_ports have a port mirror filter on these ports to redirect those frames that match the
filter to the mirror port.
• The mirror port then routes those frames it receives back to the either the C_ports or E_ports port.