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Network Architecture
It is recommended that the XstreamCORE ET 8100T
is used on an isolated lossless network when using iSCSI
• When using both Ethernet data ports on the
XstreamCORE ET 8100T each port must be assigned to an
independent subnet in order to achieve full bandwidth. The
XstreamCORE's Ethernet management port must also be
assigned to an independent subnet. All Ethernet port subnets
must not overlap.
• Spanning-tree protocol (STP) should be disabled on the
switch ports being used for iSCSI traffic. This would mean
ports connected to the 8100T and all iSCSI initiators.
If you do need STP enabled it is recommended that
you enable the STP FastPort feature on your switch
• Global flow control should be enabled on the switch ports
and iSCSI initiators.
It is recommended that global flow control is
employed for iSCSI traffic to limit dropped packets if possible.
• It is recommended that unicast storm control is disabled
on your switch.
• It is recommended that you USE broadcast and multicast
storm control on your switch.
• Jumbo frames (large MTU's) should be enabled on all
switch ports, the iSCSI initiators, and the 8100T data ports for
optimal performance.
• If Virtual LAN (VLAN) is required, ATTO recommends
configuring VLAN on your switch. A switch created VLAN is a
broadcast domain, which helps separate traffic on switch
ports.
iSCSI Targets and Tape Devices
•
When multiple tape devices are expected to be used at
the same time it is recommended to map a single tape
device per iSCSI target. Automatic mapping mode does
this.
•
Evenly split access to multiple tape devices across both
data ports. For example, if accessing two tapes across
two iSCSI targets, log into one iSCSI target using the
portal on data port 1 and the other using the portal
through data port 2.
Jumbo Frames
•
Care should be taken to ensure end-to-end path
maximum transmission unit (MTU) support. Failure to
provide a consistent configuration may result in packet
4 XstreamCORE iSCSI Best Practices
fragmentation. All equipment on the same layer 2
network (the same LAN or VLAN) must support the same
frame size.
•
If the MTU is increased on one end device, the switch
and receiving end must also be configured for larger
MTUs. A mixture of devices configured for jumbo frames
and standard frames on the same network can cause
performance issues.
Some vendors include the headers in the size
settings while others do not. This may require that equipment
from different vendors be configured to different values to
make the settings match.
Network Configuration
•
When configuring the IP address for Data Ports (DP1 &
DP2), they should be configured on two different
Ethernet LAN segments. The default port for iSCSI is
3260. DHCP should lease two separate subnets. For
example:
•
DP1 at 192.168.1.0/24 and DP2 at 192.168.2.0/24.
IPv6 Connections
IPv6 iSCSI connections may only be made to statically
assigned or DHCP dynamically assigned IPv6 addresses on the
data ports. For this reason, data port link local addresses
(addresses beginning with fe80) are not shown by either the
Info or get IPV6Address CLI commands.
Discovery Target Visibility
Access Control Lists (ACLs) must be enabled on a target basis
to prevent initiators from discovering a particular
XstreamCORE target. Once enabled, only initiators configured
to be on the whitelist will be able to discover that target. If
Access Control is disabled for a target, any initiator with
access to the same network the XstreamCORE is located on
will be able to discover and connect to that target.
Access Control Lists
Use the following steps to create an Access Control entry for
any target node:
Create a CLI session.
Use Set AccessControl [Target] enabled to configure that
target node to use ACLs.
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