IBM Storwize V7000, Введение и руководство по внедрению

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Chapter 11. SAN connections and configuration
471
FCoE connectivity
Figure 11-10 shows an example of FCoE connectivity of a compute node to IBM Flex System
V7000 Storage Node where the I/O module switch used is a IBM Flex System Fabric CN4093
10Gb Converged Scalable Switch, this provides both FCF and DCB functionality.
Figure 11-10 Compute node with CNA and FCF I/O module switch
Fibre Channel Forwarders
The IBM Flex System Fabric CN4093 10Gb Converged Scalable Switch has an optional Fibre
Channel Forwarder. The FCF function is the FC switching element in an FCoE SAN. It
provides functions that are analogous to the functions provided by the FC switch in a
traditional FC SAN. The most basic function is the forwarding of FCoE frames received on
one port to another port based on the destination address in the encapsulated FC frame. The
FCF is also the entity that handles FC logins, routing, zoning, and other FC services. As
shown in Figure 11-8 on page 469 the lower layers of FC have changed with FCoE, but the
upper layers are intact. The forwarding of FCoE frames between a compute node and an IBM
Flex System V7000 Storage Node are therefore contained within the IBM Flex System
Enterprise Chassis where the CN4093 provides the FCF switching functionality.
The CN4093 switch with its FCF function and FC ports can connect to external Fibre Channel
SANs. In this case, the CN4093 10 Gb Ethernet switch provides a gateway device function
between FCoE and FC, transmitting frames between the two types of networks. As shown in
Figure 11-10, IBM Flex System V7000 Storage Node can manage external storage
controllers using this capability to attach to FC SAN fabrics.
11.4.3 FCoE port types
In an FCoE network, virtual links are used across the lossless Ethernet network in place of
the physical links in the FC network. The server negotiates a connection to the FCF device
across the Ethernet network by using the FCoE Initialization Protocol (FIP). The server end of
this connection is called a
VN_Port
. The FCF end is called the
VF_Port
. Two FCFs can also
negotiate a connection across the Ethernet network, in which case the (virtual) ISL has
VE_Ports at both ends. Figure 11-11 shows the connection types between the compute node
and the I/O module switches. As shown, if the IBM Flex System Enterprise Chassis I/O
module switches were connected they would use VE_Ports at each end. In the IBM Flex
System Enterprise Chassis the FCFs will
not
be connected, the VE_Port connection is used
as an illustration example only in Figure 11-11.