To support the massive Internet expansion of recent years, carriers significantly increased the capacity of backbone and core networks. Overview This otherid2ic describes the background and functions of LCAS, and the advantages of LCAS to networks. Basic Concepts Learning the basic . Another EoS protocol that is attracting a great deal of interest is link capacity adjustment scheme (LCAS), a method of using SONET/SDH.

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Hence this provide a better throughput compared to native Ethernet transport. Although autonomous addition after a failure is repaired is hitless, removal of a member due to path layer failures is not hitless. This is a bit used to acknowledge the detection of renumbering of the sdg or a change in the number of VCG members. Up to VC-3 or VC-4 paths can be concatenated together to form a single larger virtually concatenated group. Ethernet frames which are to be sent on the SDH link are sent through an “encapsulation” block typically Generic Framing Procedure or GFP to create a synchronous stream of data from the asynchronous Ethernet packets.

Although SONET and SDH were originally designed to transport voice traffic, advent of these new mechanisms has made it perfectly suitable for carrying more dynamic and bursty data traffic. The transmitter lxas the receiver communicate using control packets to ensure smooth transition from one state to another. The source node starts sending F ADD control commands in the selected member.


This member is provisioned to participate in the VCG and has a good path to the receiver. LCAS uses 7 others for its purposes, leaving 5 reserved for future development. This member is in the process of being added to the VCG.

The following control words are sent from source to the receiver in order to carry out dynamic provisioning functions.

From Wikipedia, the free encyclopedia. LCAS is resident in the H4 byte of the path overhead, the same byte as virtual concatenation.

Link Capacity Adjustment Scheme – Wikipedia

This page was last edited on 16 Julyat This acknowledgment is used to synchronize the transmitter and the receiver. Or, the lcass has received and acknowledged a request for addition of this member. The synchronous stream of encapsulated data is then passed through a mapping block which typically uses virtual concatenation VCAT to route the stream of lcaa over one or more SDH paths.

This member is in the process of being deleted from the VCG.

The network management system orders the source to add a new member e. This member is provisioned to participate in the VCG and has a failed path to the receiver. This capability is particularly useful in environments where dynamic adjustment of capacity is important. The incoming signal for this member experiences no failure condition. The following control words are sent from the receiver to the transmitter.

This member is not provisioned to participate in the VCG. The paths within a group are referred to as “members”.


Status messages are continuously exchanged and consequent actions taken. The status of all the members is returned to the transmitter in the control packets of each member.

See All Related Store Items. The incoming signal for this member experiences some failure condition, or an incoming request for removal of a member has been received and acknowledged. Computer network stubs Ethernet Synchronous optical networking Network protocols.

Link Capacity Adjustment Scheme

This computer networking article is a stub. The source sees the R OKassigns the member a sequence number that is one higher than the number currently in use. You can help Wikipedia by expanding it.

The destination notices the F IDLE command and immediately drops the channel from the reassembly process. Each word is associated with a sd member i.

In the descriptions lcws, we use the term member to denote a VC. Multiple members can be added simultaneously for fast resizing. The following is a typical sequence lcws adding a member to the group. As this is byte interleaved, it provides a better level of security compared to other mechanisms for Ethernet transport. By using this site, you agree to the Terms of Use and Privacy Policy. The operation of LCAS is unidirectional.