User manual

Network Planning
12
NXA-ENET24 Hardware Installation Guide
Making VLAN Connections
This switch supports VLANs which can be used to organize any group of network nodes into separate
broadcast domains. VLANs confine broadcast traffic to the originating group, and can eliminate
broadcast storms in large networks. This provides a more secure and cleaner network environment.
VLANs can be based on untagged port groups, or traffic can be explicitly tagged to identify the VLAN
group to which it belongs. Untagged VLANs can be used for small networks attached to a single switch.
However, tagged VLANs should be used for larger networks, and all the VLANs assigned to the inter-
switch links.
The switch also supports multiple spanning trees which allow VLANs groups to maintain a more stable
path between all VLAN members. This can reduce the overall amount of protocol traffic crossing the
network, and provide a shorter reconfiguration time when any link in the spanning tree fails.
Application Notes
1. Full-duplex operation only applies to point-to-point access (such as when a switch is attached to a
workstation, server or another switch). When the switch is connected to a hub, both devices must
operate in half-duplex mode.
2. Avoid using flow control on a port connected to a hub unless it is actually required to solve a
problem. Otherwise back pressure jamming signals may degrade overall performance for the
segment attached to the hub.
3. As a general rule the length of fiber optic cable for a single switched link should not exceed:
 1000BASE-SX: 550 m (1805 ft) using multimode fiber
 1000BASE-LX: 5 km (3.2 miles) using single-mode fiber
 100BASE-LH: 70 km (43.5 miles) using single-mode fiber
However, power budget constraints must also be considered when calculating the maximum cable length
for your specific environment.
FIG. 10 Making VLAN Connections
Finance
Marketing
VLAN 3
Untagged Ports
VLAN
unaware
switch
Tagged Port
VLAN
aware
switch
Finance
VLAN 3
R&D
VLAN 2
Testing
R&D
Testing
VLAN 1
VLAN 2
VLAN 4
VLAN 1
Tagged
Ports
12
3
4
56
7
8910
11 1 2
13
14
15 16
17
18 19 20
21 22
23
24
26
Link/Act
PoE
25
26
PWR
Diag
Stacking
Mode
PoE/Link
Console
25
Master
Slave
1
2
11
12
13
14
23
24
Stack Unit ID
When connecting to a switch that does not support IEEE 802.1Q VLAN tags, use
untagged ports.