3Com SuperStack 4 Configuration Manual page 422

434 A D: 3C
PPENDIX OM
Important
Considerations and
Recommendations
Recommendations for
Achieving Maximum
Resilience
XRN
the Command Guide supplied in PDF format on the CD-ROM that accompanies
your Switch or on the 3Com Web site.
This section contains important points and recommendations that you need to
consider or be aware of when designing a network using XRN .
Bandwidth across the XRN Interconnect is detailed in
■
Local Forwarding and DRR ensures efficient use of bandwidth across the Fabric
Interconnect.
Table 464 Bandwidth across the XRN Interconnect
Switch Model
Switch 5500G-EI
When you create a Distributed Fabric the relevant port-based tables do not
■
double in size, they remain as they were.
When Switch 5500G-EI units are in an XRN Distributed Fabric their unit IDs are
■
user configurable.
The maximum number of Switch units that can be interconnected is shown in
■
Table 465.
Table 465 Number of Switch units that can create an XRN Distributed Fabric
Switch Model
Switch 5500G-EI
It is not possible to create an XRN Distributed Fabric with Switches from
■
different SuperStack 4 5500 families, for example, a Switch 5500-EI with a
5500G-EI. You can only use Switches within an individual SuperStack 4 5500
family to create an XRN Distributed Fabric, for example, a Switch
5500G-EI 52-Port with a Switch 5500G-EI 28-Port.
3Com strongly recommends that you upgrade all Switches to be
■
interconnected to the latest software agent.
3Com recommends that you initialize a Switch unit that has previously been
■
used elsewhere in your network before you interconnect to an existing unit. If
you do not initialize the unit, problems may be caused by conflicting Switch
configurations.
When a port is operating in XRN mode it will no longer be configurable in the
■
normal way, that is, you cannot control port features such as auto-negotiation,
VLANs, static addresses, STP, Aggregated Links, Resilient Links, and so on.
To achieve maximum network-level resilience 3Com recommends that:
Servers and wiring closets are multihomed. That is, each server or wiring closet
■
is connected to both units within the Distributed Fabric.
On all multi-homed links you use link aggregation (preferably configured
■
automatically via LACP rather than configured manually) across an XRN
Distributed Fabric, and you have STP/RSTP enabled across your network. (See
"Legacy Aggregated Links"
Bandwidth across the XRN Interconnect
48 Gbps, 96 Gbps (full duplex)
Max number of units
8
on page 439 for more information.)
Table 464. Intelligent
Method
Loop