HP ProLiant DL288 ISS Technology Focus, Volume 10, Number 2 - Page 3

VEPA gives you full bridge visibility and access to bridge features. It works with many existing bridges. Configuring the basic reflective relay-forwarding mode requires minimal additions to the IEEE 802.1 standard, and many existing switches already support the feature. One example is the HP A5820X switch series. VEPA can address most VEB limitations with effectively no additional cost, minimal NIC changes, minimal bridge changes, no frame format changes, and minimal IEEE specification changes. VEPA also performs better than VEB. VEPA offloads network services, like firewalling, to an external hardware-based bridge that can perform standard network services. Offloading network services reduces the burden on CPUs and improves system performance. Virtual Station Interface discovery VSI is an internal point-to-point Ethernet LAN that connects a bridge port of a VEB or VEPA to a vNIC. Each VSI carries a single MAC service instance. The term VSI is sometimes referred to the reference point where the internal LAN attaches to the vNIC. You use the VSI discovery protocol to discover and configure a Virtual Station Interface Instance. VEPA plus Multichannel technology The IEEE identified some scenarios in which a standard tagging mechanism could enhance VEPA and VEB. HP proposed an optional multichannel technology that lets you logically separate traffic on a physical network connection or port into multiple logical channels. The colored paths in Figure 2 represent these distinct logical channels. Each logical channel operates as independent, parallel connection to the external network. You can assign the logical channel to any type of virtual switch (VEB, VEPA, and so on) or directly map it to any VM within the server. The IEEE is including multichannel technology in the IEEE 802.1Qbg EVB standard. Figure 2. VEPA with multichannel technology separates logical channels to connect to multiple VMs Multichannel technology uses existing Service VLAN tags (S-Tags) standardized in IEEE 802.1ad, which is commonly referred to as the "Provider Bridge" or "Q-in-Q" standard. Multichannel technology uses the extra S-Tag and incorporates VLAN IDs in these tags to represent the logical channels of the physical network connection. The facts Competitive bridging proposals such as VN-Tag claim that VEPA and the reflective relay become "proprietary" technology once implemented by the hypervisor and are not industry standard mechanisms. The reality is that the hypervisor defines the 3