HP 1606 Fabric OS FCIP Administrators Guide v6.4.0 (53-1001766-01, November 20 - Page 58

FCIP services license, QoS implementation over FCIP, DSCP quality of service

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3 FCIP services license FCIP services license Most of the FCIP extension services described in this chapter require the Brocade High Performance Extension over FCIP/FC license. Use the licenseShow command to verify the license is present on the hardware used on both ends of the FCIP tunnel. QoS implementation over FCIP Quality of Service (QoS) refers to policies for handling differences in data traffic. These policies are based on data characteristics and delivery requirements. For example, ordinary data traffic is tolerant of delays and dropped packets, but voice and video data are not. QoS policies provide a framework for accommodating these differences in data as it passes through a network. Fabric OS versions 6.0.0 and later provide for Fibre Channel QoS through internal QoS priorities. Those priorities can be mapped to TCP/IP network priorities. There are two options for TCP/IP network-based QoS: • Layer three DiffServ code Points (DSCP). • VLAN tagging and Layer two class of service (L2CoS). DSCP quality of service Layer three class of service DiffServ Code Points (DSCP) refers to a specific implementation for establishing QoS policies as defined by RFC2475. DSCP uses six bits of the Type of Service (TOS) field in the IP header to establish up to 64 different values to associate with data traffic priority. DSCP settings are useful only if IP routers are configured to enforce QoS policies uniformly within the network. IP routers use the DSCP value as an index into a Per Hop Behavior (PHB) table. Control connections and data connections may be configured with different DSCP values. Before configuring DSCP settings, determine if the IP network you are using implements PHB, and consult with the network administrator to determine the appropriate DSCP values. L2CoS quality of service Devices in physical LANs are constrained by LAN boundaries. They are usually in close proximity to each other, and share the same broadcast and multicast domains. Physical LANs often contain devices and applications that have no logical relationship. Also, when logically related devices and applications reside in separate LAN domains, they must be routed from one domain to the other. A VLAN is a virtual LAN network. A VLAN may reside within a single physical network, or it may span several physical networks. Related devices and applications that are separated by physical LAN boundaries can reside in the same VLAN. Also, a large physical network can be broken down into smaller VLANs. VLAN traffic is routed using 802.1Q-compliant tags within an Ethernet frame. The tag includes a unique VLAN ID, and Class of Service (CoS) priority bits. The CoS priority scheme (also called Layer two Class of Service or L2CoS), uses only the upper three bits of the TOS field, allowing eight priorities. 44 Fabric OS FCIP Administrator's Guide 53-1001766-01

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44
Fabric OS FCIP Administrator’s Guide
53-1001766-01
FCIP services license
3
FCIP services license
Most of the FCIP extension services described in this chapter require the Brocade
High Performance
Extension over FCIP/FC license
. Use the
licenseShow
command to verify the license is present on
the hardware used on both ends of the FCIP tunnel.
QoS implementation over FCIP
Quality of Service (QoS) refers to policies for handling differences in data traffic. These policies are
based on data characteristics and delivery requirements. For example, ordinary data traffic is
tolerant of delays and dropped packets, but voice and video data are not. QoS policies provide a
framework for accommodating these differences in data as it passes through a network.
Fabric OS versions 6.0.0 and later provide for Fibre Channel QoS through internal QoS priorities.
Those priorities can be mapped to TCP/IP network priorities. There are two options for
TCP/IP
network-based QoS
:
•
Layer three DiffServ code Points (DSCP).
•
VLAN tagging and Layer two class of service (L2CoS).
DSCP quality of service
Layer three class of service DiffServ Code Points (DSCP) refers to a specific implementation for
establishing QoS policies as defined by RFC2475. DSCP uses six bits of the Type of Service (TOS)
field in the IP header to establish up to 64 different values to associate with data traffic priority.
DSCP settings are useful only if IP routers are configured to enforce QoS policies uniformly within
the network. IP routers use the DSCP value as an index into a Per Hop Behavior (PHB) table. Control
connections and data connections may be configured with different DSCP values. Before
configuring DSCP settings, determine if the IP network you are using implements PHB, and consult
with the network administrator to determine the appropriate DSCP values.
L2CoS quality of service
Devices in physical LANs are constrained by LAN boundaries. They are usually in close proximity to
each other, and share the same broadcast and multicast domains. Physical LANs often contain
devices and applications that have no logical relationship. Also, when logically related devices and
applications reside in separate LAN domains, they must be routed from one domain to the other.
A VLAN is a virtual LAN network. A VLAN may reside within a single physical network, or it may span
several physical networks. Related devices and applications that are separated by physical LAN
boundaries can reside in the same VLAN. Also, a large physical network can be broken down into
smaller VLANs. VLAN traffic is routed using 802.1Q-compliant tags within an Ethernet frame. The
tag includes a unique VLAN ID, and Class of Service (CoS) priority bits. The CoS priority scheme
(also called Layer two Class of Service or L2CoS), uses only the upper three bits of the TOS field,
allowing eight priorities.