An Overview of Ethernet OAM

Networks, especially large ones, are rather tricky to effectively manage. The intricacy and complexity of the carrier ethernet services make said management tricky. When we talk about the management of carrier ethernet, we center around three things: reliability, availability, and fast recovery.

What Is OAM?

OAM in full is operations, administration, and maintenance. In a traditional network, these three things are relatively easy to achieve. It’s a different kettle of fish altogether with ethernet-based solutions like carrier ethernet.

Regardless of the underlying technology, service level agreements have to be met and this answers the question of why ethernet OAM is important.

What Does OAM Provide for You?

Performance Management

OAM measures some crucial network parameters to monitor how the network is handling business on access devices. These parameters include packet loss ratio, delay, and the number of bytes sent and received.

This is especially useful to carriers who implement it to monitor network operations. After monitoring network operation, they can adjust relevant parameters in real-time from the actionable real-time data collected from the aforementioned network operation monitoring.

In the long run, you end up saving a lot on maintenance costs.

Fault Management

Fault management is all about noticing and fixing issues as they come up. Here is how it’s done:

OAM sends detection packets simply to monitor network connectivity. The packets can be sent periodically or on demand. The packets are then traced on the IP networks to locate and diagnose faults on the ethernet network.

OAM is coupled with a protection switching protocol that triggers a device in the event of a connectivity failure. The optimal downtime for these failures is about 50 milliseconds or less, with the help of switchovers.

Testing Ethernet OAM

The testing will vary depending on which OAM feature is being validated about fault management, performance management, or monitoring. Where to begin?

Performance Monitoring

Frame Loss

Frame loss tests check for the bidirectional frame loss occurring with a peer MEP from a single endpoint. Use different frame sizes when validating frame loss in simulating real-world conditions. Frame loss tests should be done often over a long period to get a decent enough idea of how the network will behave.

Synthetic Loss

Synthetic loss tests use synthetic frames to check bidirectional frame loss that is occurring with a peer MEP from a single endpoint. Again, these tests should be conducted using different frame sizes.

Frame Delay Test

In this test, the roundtrip delay to the peer MEP is measured. Simulate real-life conditions with different frame sizes when validating frame delay.

Fault Management

The tests can vary depending on the OAM standard being used but the overall goal is the detection, verification, location, and notification of faults. Some of the tests you will see here include:

Continuity Checks

Continuity checks are for verifying the presence of an MEP on a network and the presence of peer MEPs. The transmitted frames in the carrier ethernet services are received by a peer MEP using a unicast destination address.

Alternatively, the frames can be received by all MEPs using a multicast destination address instead of the unicast destination address.

Test Function

This test involves the generation of frames with a specific test pattern and sequence number to verify the integrity of the signal received by the peer MEP. The test requires supervision on both the sending and receiving ends ergo requires two testers – one on each end of the network.

Lock Signal Test

A lock signal test is used in the generation and detection of locked signals. Whenever a lock frame is received, the tester raises the alarm.