Specifications

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Cisco MWR 2941 Mobile Wireless Edge Router Release 3.5 Software Configuration Guide, Cisco IOS Release 15.1(3)MR

OL-26895-01

Chapter 15 Configuring Ethernet OAM, CFM, and E-LMI

Understanding Microwave 1+1 Hot Standby Protocol

Figure 15-6 shows a sample physical topology for HSBY using two ODUs (active and standby) and one

IDU.

Figure 15-6 HSBY Link Protection Physical Topology

In this topology, the IDU is connected to an active and a standby ODU. While only the active ODU

handles data traffic, both ODUs process CFM and management traffic at all times. The HSBY

implementation of CFM detects connectivity failures between the IDU and each ODU and indicates

which ODU is active and handling traffic. In the event of a failure, the standby ODU assumes the role

of the active ODU.

Suspending Continuity Check Messages

Under some circumstances such as a software upgrade or a device reload, it is necessary to temporarily

suspend continuity check messages between the ODU and IDU in order to prevent unnecessary link

protection action such as a failover. In this case, the ODU sets a suspend flag within the continuity check

messages sent to the IDU indicating the amount of time until continuity check messages resume. The

IDU resumes exchanging continuity check messages with the ODU after the suspend interval has passed

or after the ODU recovers sends a continuity check message.

Note While the Cisco MWR 2941 processes continuity check suspend messages from the IDU, configuration

of continuity check messages on the Cisco MWR 2941 is not supported.

HSBY Maintenance Associations

HSBY protocol uses two types of CFM continuity check messages:

• E–CCM—An IDU-to-ODU continuity check message that functions at Ethernet CFM domain level

0. There are two active E–CCM sessions when HSBY is configured.

• P–CCM—An ODU-to-ODU continuity check message that functions at Ethernet CFM domain level

Note The IDU is only associated with the E–CCM sessions; it has outward-facing MEPs configured for each

session.

Thus, the HSBY configuration shown in Figure 15-6 consists of five separate traffic flows:

• CFM traffic between the IDU and ODU 1

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IDU

ODU 1 (Active)

ODU 2 (Standby)