Redundancy With A Backup-Group - ABB EDS500 Series Function Manual

Functions
The default value activates a weighted algorithm that tries to optimize the load on both DSL
channels adapted to the respective transmission rate of both DSL lines.
Alternatively, a MAC based distribution algorithm can be set that selects a DSL channel in
relation of source and target MAC address.
The default value for DSL channel bundling is: shutdown.
The command <set interface channel0 no shutdown> activates the DSL channel bundling.
The command <set interface channel0 shutdown> deactivates the DSL channel bundling.
The current link state of the DSL channel bundling can be displayed in an overview. Detailed
information about the data traffic that runs over an channel0 interface is also available and
can be requested alternatively via RMON (SNMP).
Commands related to DSL channel building
< s e t i n t e r f a c e c h a n n e l 0 [ n o ] s h u t d o w n >
< s e t i n t e r f a c e c h a n n e l 0 d i s t r i b u t i o n - a l g o r i t h m { m a c - b a s e d |
w e i g h t e d - l e f t - r i g h t } >
< s e t i n t e r f a c e c h a n n e l 0 a l i a s { s t r i n g 2 0 } >
< s h o w i n t e r f a c e c h a n n e l 0 >
< s h o w i n t e r f a c e c h a n n e l 0 f r a m e - c o u n t e r s >
As the DSL channel bundling is implemented in software, the reachable data rate is limited.
DSL line with individual data rates over 2.048 kbps can be configured as channel bundling.
But this does not contribute to increase the channel0 data rate. Only reliability against
failure is there.
If a DSL interface that is part of a channel bundling gets connected to a counterpart that
is not part of the channel bundling, the alarm Link aggregation mismatch will occur. In this
state the function of Spanning Tree is not guaranteed and the network is in a potentially
incoherent state. Especially when activating the DSL channel bundling you have to watch
out for this.
2.17

Redundancy with a Backup-Group

The protocol Spanning Tree over used (refer to Chapter 2.19, "Spanning Tree Protocol")
to grant the automatic switch over to an alternative route in networks with redundant
connections. Depending on the existing topology and settings the switch over may take some
seconds and block the network for this period in a worst case.
The backup group function of the EDS500 devices offers a sped-up switch over for two
redundantly connected sites. Prerequisite is that they are connected via directly point-to-
point connections. The switch-over is not protocol-based but is directly based on the link
state.
The underlying principle is that of a link aggregation without the simultaneous use of the
joint bandwidth of the single connections. Spanning Tree works transparently over this
interface called backup-group1. The interface backup-group transmits over the fastest
available connection at any time.
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Redundancy with a Backup-Group
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