Design Reference

Table Of Contents
latency The time between when a node sends a message and receipt of the
message by another node; also referred to as propagation delay.
Layer 1 Layer 1 is the Physical Layer of the Open System Interconnection (OSI)
model. Layer 1 interacts with the MAC sublayer of Layer 2, and performs
character encoding, transmission, reception, and character decoding.
Layer 2 Layer 2 is the Data Link Layer of the OSI model. Examples of Layer 2
protocols are Ethernet and Frame Relay.
Layer 2 Virtual
Services Network
The Layer 2 Virtual Services Network (L2 VSN) feature provides IP
connectivity over SPBM for VLANs. Backbone Edge Bridges (BEBs) handle
Layer 2 virtualization. At the BEBs you map the end-user VLAN to a
Service Instance Identifier (I-SID). BEBs that have the same I-SID
configured can participate in the same Layer 2 Virtual Services Network
(VSN).
Layer 3 Layer 3 is the Network Layer of the OSI model. An example of a Layer 3
protocol is Internet Protocol (IP).
Layer 3 Virtual
Services Network
The Layer 3 Virtual Services Network (L3 VSN) feature provides IP
connectivity over SPBM for VRFs. Backbone Edge Bridges (BEBs) handle
Layer 3 virtualized. At the BEBs through local provisioning, you map the
end-user IP enabled VLAN or VLANs to a Virtualized Routing and
Forwarding (VRF) instance. Then you map the VRF to a Service Instance
Identifier (I-SID). VRFs that have the same I-SID configured can participate
in the same Layer 3 Virtual Service Network (VSN).
Layer 4 The Transport Layer of the OSI model. An example of a Layer 4 protocol is
Transmission Control Protocol (TCP).
Link Aggregation
Control Protocol
(LACP)
A protocol that exists between two endpoints to bundle links into an
aggregated link group for bandwidth increase and link redundancy.
Link Aggregation
Control Protocol
Data Units (LACPDU)
Link aggregation control protocol data unit (LACPDU) is used for
exchanging information among LACP-enabled devices.
link aggregation
group (LAG)
A group that increases the link speed beyond the limits of one single cable
or port, and increases the redundancy for higher availability.
link-state
advertisement (LSA)
Packets that contain state information about directly connected links
(interfaces) and adjacencies. Each Open Shortest Path First (OSPF) router
generates the packets.
latency
January 2015 Network Design Reference for Avaya VSP 4000 Series 155
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