Hirschmann PowerMICE User manual

Redundancy L3P
Release 3.0 01/07
Technical Support
[email protected]
User Manual
Redundancy Configuration
Industrial ETHERNET Gigabit Switch
PowerMICE, MACH 4000

The naming of copyrighted trademarks in this manual, even when not specially indicated, should
not be taken to mean that these names may be considered as free in the sense of the trademark
and tradename protection law and hence that they may be freely used by anyone.
© 2007 Hirschmann Automation and Control GmbH
Manuals and software are protected by copyright. All rights reserved. The copying, reproduction,
translation, conversion into any electronic medium or machine scannable form is not permitted,
either in whole or in part. An exception is the preparation of a backup copy of the software for
your own use.
The performance features described here are binding only if they have been expressly
guaranteed in the contract. This publication has been created by Hirschmann Automation and
Control GmbH according to the best of our knowledge. Hirschmann reserves the right to change
the contents of this manual without prior notice. Hirschmann can give no guarantee in respect
of the correctness or accuracy of the details in this publication.
Hirschmann can accept no responsibility for damages, resulting from the use of the network
components or the associated operating software. In addition, we refer to the conditions of use
specified in the license contract.
Printed in Germany (27.2.07)
Hirschmann Automation and Control GmbH
Stuttgarter Straße 45-51
72654 Neckartenzlingen
Tel. [phone]-0107

Contents
Redundancy L3P
Release 3.0 01/07 3
Contents
About this Manual 5
Key 7
Introduction 9
Comparison of the Redundancy Procedures 11
1 Rapid Spanning Tree 13
1.1 The Spanning Tree Protocol 14
1.1.1 The Tasks of the STP 14
1.1.2 The bridge parameters 15
1.1.3 Rules for creating the tree structure 17
1.1.4 Example: determination of root paths 20
1.1.5 Example: manipulation of root paths 22
1.1.6 Example: manipulation of a tree structure 24
1.2 The Rapid Spanning Tree Protocol 25
1.2.1 Port roles 25
1.2.2 Port states 28
1.2.3 Spanning Tree Priority Vector 29
1.2.4 Fast reconfiguration 29
1.3 Configuring the Rapid Spanning Tree 31
2 Redundant ring structure – MRP-Ring 39
2.1 The MRP-Ring 39
2.2 Configuring the MRP-Ring 41
3 Redundant ring structure – HIPER-Ring 45
3.1 The HIPER-Ring 45
3.2 Configuring the HIPER-Ring 47

Contents
4Redundancy L3P
Release 3.0 01/07
4 Redundant coupling 51
4.1 The Variants of Redundant Coupling 51
4.2 Configuring the Redundant Coupling 53
4.2.1 STAND-BY Switch 53
4.2.2 One-switch coupling 56
4.2.3 Two-switch coupling 63
4.2.4 Two-switch coupling with control line 70
5 Link Aggregation 77
5.1 Configuring the link aggregation 78
5.2 HIPER-Ring and Link Aggregation 82
6VRRP 83
6.1 Configuring the VRRP 84
6.1.1 General settings 84
6.1.2 Settings per port 84
6.1.3 Setting up the VRRP router interface 86
6.1.4 Configuring the VRRP router interface 86
6.1.5 Deleting the VRRP router interface 87
6.2 Statistics 88
A Appendix 89
Hirschmann Competence 90
FAQ 91
Reader's comments 93
Index 95

About this Manual
Redundancy L3P
Release 3.0 01/07 5
About this Manual
The “Redundancy Configuration” user manual contains all the information
you need to select a suitable redundancy procedure and configure it.
The “Installation” user manual contains a device description, safety instruc-
tions, a description of the display, and all the other information that you need
to install the device before you begin with the configuration of the device.
The “Basic Configuration” user manual contains all the information you need
to start operating the switch. It takes you step by step from the first startup
operation through to the basic settings for operation in your environment.
You will find detailed descriptions of how to operate the individual functions
in the “Web-based Interface” and “Command Line Interface” reference
manuals

About this Manual
6Redundancy L3P
Release 3.0 01/07

Key
Redundancy L3P
Release 3.0 01/07 7
Key
The designations used in this manual have the following meanings:
DList
VWork step
USubheading
Indicates a cross-reference with a stored link.
Note: A note emphasizes an important fact or draws your attention to
adependency.
Courier font ASCII representation in user interface
Symbols used:
Execution in the Web-based Interface user interface
Execution in the Command Line Interface user interface
Router
Switch
Bridge

Key
8Redundancy L3P
Release 3.0 01/07
Hub
A random computer
Configuration computer
Server

Introduction
Redundancy L3P
Release 3.0 01/07 9
Introduction
The Switch contains a wide variety of redundancy functions:
DRapid Spanning Tree Algorithm
DMRP-Ring
DHIPER-Ring
DRedundant coupling of HIPER-Rings and network segments
DLink Aggregation
There are three tools for operating these functions:
DWeb-based Management (supplied with the switch)
for easy configuration of the agent (see "Web-based Interface" reference
manual).
DCommand Line Interface (supplied with the Switch)
for setting basic functions (see "Command Line Interface" manual).
DHiVision Network Management
for easy configuration of all agents (see "HiVision Hirschmann Network
Management" manual).

Introduction
10 Redundancy L3P
Release 3.0 01/07

Comparison of the Redundancy Proce-
Redundancy L3P
Release 3.0 01/07 11
Comparison of the Redundancy
Procedures
RSTP MRP Ring HiPER Ring Redundant
Coupling Link Aggregation
Switch-over
time
< 30 s,
< 1 s typically
(STP < 30 s)
Heavily
dependent on
the number of
switches
< 0,5 s
Practically
independent
of the number
of switches
< 0,5 s
Practically
independent
of the number
of switches
typ 0.15 s -
Network
topology
Random
structure
Ring Ring Coupling of
network segment/
rings via a main
line and a
redundant line
Coupling of
network
segments via
multiple active
lines with
dynamic load
distribution
Table 1: Features of the Redundancy Procedures

Comparison of the Redundancy Proce-
12 Redundancy L3P
Release 3.0 01/07

Rapid Spanning Tree
Redundancy L3P
Release 3.0 01/07 13
1 Rapid Spanning Tree
Note: The Spanning Tree protocol and the Rapid Spanning Tree protocol are
protocols for MAC bridges. They are described in the standards IEEE
802.1D-2004 and IEEE 802.1w. For this reason, the following description of
these protocols usually employs the term bridge instead of switch.
Local area networks are becoming ever larger. This is true both for their geo-
graphic size as well as for the number of stations they include. As the net-
works become larger, there are reasons why it often makes sense to imple-
ment several bridges:
Dreduce network load in subnetworks,
Dcreate redundant connections and
Dovercome distance.
Using many bridges with multiple, redundant connections between the sub-
networks can lead to loops and thus to the complete failure of the network.
The (Rapid) Spanning Tree Algorithm was developed to prevent this. The
Rapid Spanning Tree Protocol (RSTP) enables redundancy by interrupting
loops.
RSTP is a further development of the Spanning Tree Protocol (STP) and is
compatible with it. If a connection or a bridge fails, the STP requires up to 30
seconds to reconfigure. This was no longer acceptable in time-sensitive ap-
plications. The STP was therefore developed into the RSTP, leading to re-
configuration times of less than a second.
Note: The standard demands that all bridges of a network have to work with
the (Rapid) Spanning Tree Algorithm. If, however, both protocols are used
simultaneously, there are no advantages to using the faster reconfiguration
with RSTP.

Rapid Spanning Tree
14
1.1 The Spanning Tree Protocol
Redundancy L3P
Release 3.0 01/07
1.1 The Spanning Tree Protocol
Because RSTP is a further development of the STP, all the following descrip-
tions of the STP also apply to the RSTP.
1.1.1 The Tasks of the STP
The Spanning Tree Algorithm reduces network topologies that are set up
using bridges, and that have ring structures with redundant connections, to a
tree structure. In doing this, STP divides up the ring structures on the basis
of specified rules by deactivating redundant paths. If a path is interrupted by
mistake, the STP activates the path just deactivated. This enables redundant
connections for increased data safety.
In forming the tree structure, the STP determines what is known as a root
bridge. This forms the basis of the STP tree structure.
Features of the STP algorithm:
Dit reconfigures automatically the tree structure in case of a bridge failure
or break in a data path,
DIt stabilizes the tree structure up to the maximum network size (up to 39
hops, depending on the setting for “Max. Age”),
DIt stabilizes within a short, known time,
DIt produces a reproducible topology that can be pre-defined by manage-
ment,
DIt is transparent to the terminal equipment,
Dby creating a tree structure it results in a low network load compared to
the available transmission capacity.

Rapid Spanning Tree
Redundancy L3P
Release 3.0 01/07
1.1 The Spanning Tree Protocol
15
1.1.2 The bridge parameters
Each bridge is uniquely described by the following parameters:
DBridge Identifier,
DRoot path costs of the bridge ports
DPort Identifier.
UBridge Identifier
The bridge identifier is 8 bytes long. The two highest-value bytes are the
priority number. The default setting for the priority number is 32 768, but
the Management Administrator can change this when configuring the
network. The six lowest-value bytes of the bridge identification are the
MAC address of the bridge. The MAC address guarantees that every
bridge has a different bridge identification.
The bridge with the numerically lowest-value bridge identifier has the
highest priority.
Fig. 1: Bridge identifier
URoot path costs
Each path connecting two bridges has transmission costs assigned to it.
The management administrator sets this value and specifies it for each
path when configuring a bridge (see Table 2 on page 16). It assigns the
higher path costs to paths with lower transmission speeds.
Alternatively, the Management Administrator can define the path costs.
Like the switch, it assigns the higher path costs to paths with lower trans-
mission speeds. Because he essentially has a free hand in specifying
this value, he has a tool for ensuring that in case of redundant paths one
path will be favored over the others.
The root path costs are calculated by adding up the individual path costs
MAC AddressPriority
LSBMSB

Rapid Spanning Tree
16
1.1 The Spanning Tree Protocol
Redundancy L3P
Release 3.0 01/07
for the paths that a data packet must traverse between the port of a
bridge and the root.
Fig. 2: Path costs
Note: If link aggregation (see “Link Aggregation” on page 77) is used to com-
bine the connection lines between switches into a trunk, then the path costs
are reduced in accordance with the number of connections that are combi-
ned in a trunk.
Data rate Recommended value Recommended range Possible range
<=100 KBit/s 200 000 000* 20 000 000-200 000 000 1-200 000 000
1 MBit/s 20 000 000* 2 000 000-200 000 000 1-200 000 000
10 MBit/s 2 000 000* 200 000-20 000 000 1-200 000 000
100 MBit/s 200 000* 20 000-2 000 000 1-200 000 000
1 GBit/s 20 000 2 000-200 000 1-200 000 000
10 GBit/s 2 000 200-20 000 1-200 000 000
100 GBit/s 200 20-2 000 1-200 000 000
1 TBit/s 20 2-200 1-200 000 000
10 TBit/s 21-20 1-200 000 000
Table 2: Recommended path costs of RSTP according to the data rate
* Bridges conformant to IEEE Std 802.1D, 1998 Edition, i.e., that support only 16 bit
values for path cost, should use 65 535 as the path cost for these link speeds when
used in conjunction with bridges that support 32 bit path cost values.
Ethernet (100 Mbit/s)
Ethernet (10 Mbit/s)
PC Path costs
PC = 2 000 000
PC = 200
000
PC = 200
000 Bridge 1
Bridge 2 Bridge 3

Rapid Spanning Tree
Redundancy L3P
Release 3.0 01/07
1.1 The Spanning Tree Protocol
17
UPort identification
The port identification consists of two bytes. One part, the lower-value
byte, reflects a fixed relationship to the physical port number. This part
ensures that no port in a bridge receives the same designation as
another port in the same bridge. The second part contains the priority
number which is set by the management administrator (default:128). It is
also true here that the port with the lowest numerical value for its port
identifier is the one with the highest.
Fig. 3: Port identification
1.1.3 Rules for creating the tree structure
UBridge information
In order to compute their tree structures, the bridges need information
about other bridges that are present in the network. This information is
obtained by each bridge sending a BPDU (Bridge Protocol Data Unit) to
all other bridges.
Along with other information, the BPDU contains the
Dbridge identifier,
Droot path costs, and
Dport identification
(see IEEE 802.1D).
Priority Port number
MSB LSB

Rapid Spanning Tree
18
1.1 The Spanning Tree Protocol
Redundancy L3P
Release 3.0 01/07
UBuilding the tree structure
DThe bridge with the numerically smallest bridge identifier is made the
root bridge. It forms the root of the tree structure.
DThe structure of the tree depends upon the root path costs. The struc-
ture that is chosen is the one that provides the lowest path costs bet-
ween each individual bridge and the root bridge.
DIf there are multiple paths with the same root path costs, the priorities
of the bridge identifications for the bridges connected to this path de-
termine which bridge is blocked.
DIf there are two paths leading away from a single bridge with the same
root path costs, the port identification is used as the last criterion for
determining which path is used (see Fig. 3). It decides which port is
selected.

Rapid Spanning Tree
Redundancy L3P
Release 3.0 01/07
1.1 The Spanning Tree Protocol
19
Fig. 4: Flow chart for determining root path
Equal
path costs?
Determine root path
no
yes
Equal
priority in
bridge identification?
Equal
port priority?
yes
yes
Path with lowest
path costs = root path
Path with highest
port priority
= root path
Path with highest
priority in bridge
identification = root path
no
no
Path with lowest
port number
= root path
Root path determined

Rapid Spanning Tree
20
1.1 The Spanning Tree Protocol
Redundancy L3P
Release 3.0 01/07
1.1.4 Example: determination of root paths
Using the network diagram (see Fig. 5), it is possible to follow the logic in the
flow chart (see Fig. 4) for determining the root path. The Administrator de-
fined a different priority in the bridge identification for each bridge. The bridge
with the numerically smallest bridge identification (in this case, bridge 1) is
selected as the root bridge. In this example the partial paths all have the
same path costs. The path between bridge 2 and bridge 3 is removed becau-
se a connection from bridge 3 to the root bridge via bridge 2 would result in
twice the path costs.
The path from bridge 6 to the root bridge is interesting:
DThe path via bridges 5 and 3 generates the same root path costs as the
path via bridges 4 and 2.
DThe path via bridge 4 is selected because the numerical value 28 672 for
the priority in the bridge identifier is less than the numerical value 32 768.
DThere are however two paths between bridge 6 and bridge 4. In this case,
the larger port priority is decisive.