Vlans; Information About Vlans - Cisco Nexus 1000V Troubleshooting Manual

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VLANs

This chapter describes how to identify and resolve problems that might occur when implementing
VLANs.
This chapter includes the following sections:
• Information About VLANs, page 12-1
• Initial Troubleshooting Checklist, page 12-2
• Cannot Create a VLAN, page 12-3

Information About VLANs

VLANs can isolate devices that are physically connected to the same network, but are logically
considered to be part of different LANs that do not need to be aware of one another.
We recommend using only following characters in a VLAN name:
a-z or A-Z
•
0 - 9
•
- (hyphen)
•
_ (underscore)
•
Consider the following guidelines for VLANs:
• Keep user traffic off the management VLAN; keep the management VLAN separate from user data.
Note We recommend that you enable sticky Address Resolution Protocol (ARP) when you configure private
VLANs. ARP entries learned on Layer 3 private VLAN interfaces that are sticky ARP entries. For
security reasons, private VLAN port sticky ARP entries do not age out.
• IGMP only runs on the primary VLAN and uses the configuration of the primary VLAN for all
secondary VLANs.
• Any IGMP join request in the secondary VLAN is treated as if it is received in the primary VLAN.
• Private VLANs support these Switched Port Analyzer (SPAN) features:
OL-28795-01
– You can configure a private VLAN port as a SPAN source port.
– You can use VLAN-based SPAN (VSPAN) on primary, isolated, and community VLANs or use
SPAN on only one VLAN to separately monitor egress or ingress traffic.
C H A P T E R
Cisco Nexus 1000V Troubleshooting Guide, Release 4.2(1)SV2(2.1)
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12-1