Protection Switching
Chapter 13
FA4800 User Manual
Release 1.9.30
13-5
Protection Switching
Protection switching occurs upon failure in the ring.
The Ethernet service restoration time depends on the number of hops in the
ring. With four hops the Ethernet service is restored in less than 50 ms.
In single and dual homed topologies the service restoration may take longer
due to the aging time of the external switches. Switches that are immedi-
ately aware of routing changes reduce the restoration time.
Hardware Considerations
Ethernet Ring Protection is supported by the IDU-C, IDU-E and PoE.
A typical Ring Protection Link consists of an IDU-C or new style IDU-E, a
PoE and two ODUs as shown in
Figure 13-2
. Hence one end of the RPL
and of ring controlled links, as shown in
Figure 13-2
has to be an IDU. It is
recommended to have an IDU at each node to have the flexibility to change
the RPL.
Repeater sites
Some of the hops are connected through Ceragon links with PoE devices, not
supporting ring functionality:
Shared ring
Ceragon rings with shared hops.
Note:
•
A Ceragon link hop can be a part of up to 4 rings
•
The RPL cannot be a shared link
•
The two RPLs should use different Minimum Time for Activation values
to prevent duplicate action causing a loop
Table 13-1: Topologies supported by Ceragon Ethernet Ring (Continued)
