High-Availability Seamless Redundancy (Hsr); Hsr Multicast Topology; Hsr Unicast Topology; Figure 269: Hsr Multicast Topology - GE MiCOM P40 Technical Manual

Hide thumbs Also See for MiCOM P40:

Table of Contents

HIGH-AVAILABILITY SEAMLESS REDUNDANCY (HSR)

HSR is standardized in IEC 62439-3 (clause 5) for use in ring topology networks. Similar to PRP, HSR provides

bumpless redundancy and meets the most demanding needs of substation automation. HSR has become the

reference standard for ring-topology networks in the substation environment. The HSR implementation of the

redundancy Ethernet board (REB) is compatible with any standard HSR device.

HSR works on the premise that each device connected in the ring is a doubly attached node running HSR (referred

to as DANH). Similar to PRP, singly attached nodes such as printers are connected via Ethernet Redundancy Boxes

When a DANH is sending a multicast frame, the frame (C frame) is duplicated (A frame and B frame), and each

duplicate frame A/B is tagged with the destination MAC address and the sequence number. The frames A and B

differ only in their sequence number, which is used to identify one frame from the other. Each frame is sent to the

network via a separate port. The destination DANH receives two identical frames, removes the HSR tag of the first

frame received and passes this (frame D) on for processing. The other duplicate frame is discarded. The nodes

forward frames from one port to the other unless it was the node that injected it into the ring.

Only about half of the network bandwidth is available in HSR for multicast or broadcast frames because both

duplicate frames A & B circulate the full ring.

With unicast frames, there is just one destination and the frames are sent to that destination alone. All non-

recipient devices simply pass the frames on. They do not process them in any way. In other words, D frames are

produced only for the receiving DANH. This is illustrated below.

P446SV-TM-EN-1

Chapter 21 - Communications

Singly Attached