Fabric OS Administrator's Guide v7.0.0 (53-1002148-02, June 2011)

66 Fabric OS Administrator’s Guide
53-1002148-02
Gateway links
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Quality of Service (QoS) is a licensed traffic shaping feature available in Fabric OS. QoS allows the
prioritization of data traffic based on the SID and DID of each frame. Through the use of QoS zones,
traffic can be divided into three priorities: high, medium, and low. The seven data virtual channels,
VC8 through VC14, are used to multiplex data frames based upon QoS zones when congestion
occurs. For more information on QoS zones, refer to Chapter 20, “Optimizing Fabric Behavior”. This
example is illustrated in Figure 8.
FIGURE 8 Virtual channels on a QoS-enabled ISL
Gateway links
A gateway merges SANs into a single fabric by establishing point-to-point E_Port connectivity
between two Fibre Channel switches that are separated by a network with a protocol such as IP or
SONET.
Except for link initialization, gateways are transparent to switches; the gateway simply provides
E_Port connectivity from one switch to another. Figure 9 shows two separate SANs, A-1 and A-2,
merged together using a gateway.