Specifications

126 IBM Flex System p260 and p460 Planning and Implementation Guide
5.2.2 VLANs
Virtual LANs (VLANs) are commonly used in the Layer 2 network to split up
groups of network users into manageable broadcast domains, to create a logical
segmentation of workgroups, and to enforce security policies among logical
segments. VLAN considerations include the number and types of VLANs
supported, VLAN tagging protocols supported, and specific VLAN configuration
protocols implemented.
All IBM Flex System switch modules support the 802.1Q protocol for
VLAN tagging.
Another usage of 802.1Q VLAN tagging is to divide one physical Ethernet
interface into several logical interfaces that belong to more than one VLAN. A
compute node can send and receive tagged traffic from several VLANs on the
same physical interface. This task can be done with network adapter
management software (the same used for NIC teaming). Each logical interface
appears as a separate network adapter in the operating system, with its own set
of characteristics, such as IP addresses, protocols, and services.
Having several logical interfaces can be useful in cases when an application
requires more than two separate interfaces and you do not want to dedicate a
whole physical interface to it (for example, not enough interfaces or low traffic). It
might also help to implement strict security policies for separating network traffic
using VLANs, while having access to server resources from other VLANs,
without needing to implement Layer 3 routing in the network.
To be sure that the application deployed supports logical interfaces, check the
application documentation for possible restrictions applied to the NIC teaming
configurations, especially in the case of a clustering solutions implementation.
For more information about Ethernet switch modules, see IBM PureFlex System
and IBM Flex System Products & Technology, SG24-7984.