Netgear XCM8810 - 8800 SERIES 10-SLOT CHASSIS SWITCH ユーザーズマニュアル
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Chapter 18. STP
NETGEAR 8800 User Manual
desirable to have multiple STP domains operating in a single VLAN, one for each looped
area.
area.
The justifications include the following:
•
The complexity of the STP algorithm increases, and performance drops, with the size and
complexity of the network. The 802.1D standard specifies a maximum network diameter
of seven hops. By segregating a big VLAN into multiple STPDs, you reduce complexity
and enhance performance.
of seven hops. By segregating a big VLAN into multiple STPDs, you reduce complexity
and enhance performance.
•
Local to each site, there may be other smaller VLANs that share the same redundant
looped area with the large VLAN. Some STPDs must be created to protect those VLANs.
The ability to partition VLANs allows the large VLAN to be “piggybacked” in those STPDs
in a site-specific fashion.
The ability to partition VLANs allows the large VLAN to be “piggybacked” in those STPDs
in a site-specific fashion.
has five domains. VLANs green, blue, brown, and yellow are local to each domain.
VLAN red spans all of the four domains. Using a VLAN that spans multiple STPDS, you do
not have to create a separate domain for VLAN red. Instead, VLAN red is “piggybacked” onto
those domains local to other VLANs.
not have to create a separate domain for VLAN red. Instead, VLAN red is “piggybacked” onto
those domains local to other VLANs.
Figure 38. VLANs Spanning Multiple STPDs
In addition, the configuration in
has these features:
•
Each site can be administered by a different organization or department within the
enterprise. Having a site-specific STP implementation makes the administration more
flexible and convenient.
flexible and convenient.
•
Between the sites the connections usually traverse distribution switches in ways that are
known beforehand to be “safe” with STP. In other words, the looped areas are already
well-defined.
well-defined.
EMISTP Deployment Constraints
Although EMISTP greatly enhances STP capability, these features must deployed with care.
This section describes configuration issues that, if not followed, could lead to an improper
deployment of EMISTP. This section also provides the following restrictive principles to abide
by in network design:
This section describes configuration issues that, if not followed, could lead to an improper
deployment of EMISTP. This section also provides the following restrictive principles to abide
by in network design:
EX_051
S1
S3
VLAN yellow
VLAN red
VLAN red
VLAN brown
S2
S4
VLAN red
VLAN green
VLAN red
VLAN blue