How to Replace an Huawei ONU Rapidly?

How to Replace an Huawei ONU Rapidly?

To replace a faulty optical network unit (ONU) on a live network, you need to reload the configurations after the replacement or back up the data before loading the configurations. The operations are complicated and prone to errors. Using the network management system (NMS) to replace the ONU improves the efficiencies in device replacement and configuration loading, and at the same time reduces the error probabilities. There are five steps for replacing an ONU rapidly.

1. Configure automatic backup policies and automatic upgrade policies. (This is the prerequisite of the replacement.)
   • After the automatic backup policy is configured, the device backs up data at the configured time. The latest backup database will be used during the replacement.
   • After the automatic upgrade policy is configured, the NMS will create an automatic ONU upgrade task to upgrade the ONU if the ONU version is different from the target version set in the automatic upgrade policy.
2. Replace the ONU and power on the ONU to ensure that the optical link on the device is normal.
3. Start the ONU replacement operation on the NMS.
4. Bind the MAC address of the new ONU on the NMS.
5. Check the configurations and verify the services after the replacement.

In step 1, you only need to configure the automatic backup policy and automatic upgrade policy once. To replace ONUs in future, you only need to rebind the ONU MAC addresses on the NMS.

More related:

How to configure Clock Synchronization?

How do Adding an ONU to an OLT?

How to configure the Management Channel Between OLT and ONU?

What Is MAC Address Management?

MAC address management is a basic Layer 2 management feature that enables system administrators to use the functions listed in the following table.

Sub-function of MAC Address Management:

Setting the MAC address aging time
Limiting the number of learnable dynamic MAC addresses
Setting the static MAC address

Benefits
Benefits for Carriers
1, The system ages dynamic MAC addresses to ensure timely updates of the MAC address table. If the MAC address table is full and not updated, the system will fail to learn new MAC addresses and will consequently fail to forward data.
2, By limiting the number of learnable dynamic MAC addresses, the system administrator can limit the number of MAC addresses that can be used to enter the network and hence alleviate the load of network devices.
3, By configuring static MAC addresses, the system administrator prohibits unauthorized users from accessing the system.

Benefits for Subscribers

Improved user security: After the system administrator sets the static MAC address of a service port and sets the maximum number of learnable MAC addresses to 0, the port receives only user data carrying the specified static MAC address.
The access node provides multiple MAC address security features to protect networks against forged MAC addresses, please refer to 23 MAC Address Security Features.

Address Management Process
MAC address management includes MAC address table establishment and management.

Establishing MAC Address Tables
The system establishes a MAC address table by learning source MAC addresses or after users configure static MAC address entries.
MAC address learning
− When Huawei OLT functions as a Layer 2 switching device, it learns MAC addresses in the distributed mode. Specifically, each board learns the source MAC address of packets sent from the board of its own and then forwards packets according to their destination MAC addresses. The learned MAC addresses are stored in the system buffer. Generally, the system buffer can hold a limited number of MAC address entries. If all these entries are filled in, no more MAC addresses can be learned.
− Configuration command: mac-address learning vlan
Configuration of static MAC address entries
− A user can manually configure static MAC address entries in which user device MAC addresses are bound to ports. After this configuration, the packets whose MAC addresses are included in the MAC address entries are always forwarded through the bound ports. This configuration improves the efficiency for forwarding packets and improves the security of ports because it denies access from unauthenticated users. This method of establishing MAC address tables is widely used in private networks.
− Configuration command: mac-address static
The following table shows an example of a simplified MAC address table established by configuring static MAC address entries. The table lists the mapping between MAC addresses, ports, and VLAN IDs.

Managing MAC Address Tables

When managing MAC address tables, users can configure MAC-related attributes as allowed by system resources and network security policies against potential risks. The optimized MAC address tables can better meet requirements of a live network. These MAC-related attributes are as follows:
Maximum number of MAC addresses learned based on service flows
− After the number of access users reaches the limit, no new access user addresses will be learned. This attribute setting applies to networks, such as residential access networks and low-security internal enterprise networks, that have fixed access users but are not sufficiently secure.

Setting the function of sensing excess MAC addresses
When a lot of MAC addresses are learnt by the system, it is difficult for trouble locating. When the function of sensing excess MAC addresses is enabled, the board software queries the actual MAC address specifications of the board every 15 minutes and determines whether an alarm needs to be reported according to the query result. If the query result exceeds the upper threshold for sensing excess MAC addresses set by users, an excess MAC address alarm is generated. If the query result is smaller than the lower threshold for sensing excess MAC addresses set by users, a fault clearing alarm is generated.
Configuration command: overload-aware mac-address
MAC address aging
Generally, the system automatically establishes a MAC address table by learning source MAC addresses. The established MAC address table has to be updated according to network changes. However, after the network topology changes, the dynamic MAC address entries will not be automatically updated in a timely manner. Then the system cannot learn more MAC addresses and user data

ARP on main control board SCUN, SCUH, MPLA is am important element when engineer choose OLT

ARP on main control board SCUN and SCUH on Huawei MA5600T, MPLA on MA5800 is am important element when engineer choose OLT, then what is ARP?

The Address Resolution Protocol (ARP) is an Internet protocol used to map IP addresses to MAC addresses.

Purpose
To communicate with each other, the sending device must know the network-layer IP address of the receiving device. IP datagrams, however, must be encapsulated with MAC addresses before they can be transmitted over the physical network. Therefore, a resolution from the known IP address to a MAC address is required.
ARP was developed to enable communication between devices.

Dynamic ARP: Devices dynamically learn and update the mapping between IP addresses and MAC addresses by exchanging ARP messages. Real-time communication is a priority, or network resources are insufficient.

Static ARP: The mapping between IP addresses and MAC addresses is manually created and cannot be dynamically modified. Communication security is a priority, and network resources are sufficient.

Gratuitous ARP:A device broadcasts gratuitous ARP packets that carry the local IP address as both the source and destination IP addresses to notify the other devices on the same network segment of its address information. Gratuitous ARP is used to check whether the local IP address conflicts with that of another device, to notify other devices on the same network segment of the new MAC address after the local network interface card is replaced, or to notify master/slave switchovers in a Virtual Router Redundancy Protocol (VRRP) backup group.

Benefits
ARP ensures Ethernet communication by mapping IP addresses at the network layer to MAC addresses at the link layer on Ethernet networks.

Principles
ARP involves the following concepts:
Address Resolution Protocol (ARP) messages
An ARP message can be an ARP request or reply message. Figure below shows the ARP message format.

ARP table

An ARP table, for example SCUN on Huawei MA5603T ARP table is 8192, contains the latest mapping between IP addresses and MAC addresses. If a host always broadcasts an ARP Request message for a MAC address before it sends an IP datagram, network communication traffic will greatly increase. Furthermore, all other hosts on the network have to receive and process the ARP Request messages, which lowers network efficiency. To solve this problem, an ARP table is maintained on each host to ensure efficient ARP operations. The mapping between an IP address and a MAC address is called an ARP entry.

ARP entries can be classified as dynamic or static.

− Dynamic ARP entries are automatically generated and maintained by using ARP messages. Dynamic ARP entries can be aged and overwritten by static ARP entries.
− Static ARP entries are manually configured and maintained by a network administrator. Static ARP entries can neither be aged nor be overwritten by dynamic ARP entries.
Before sending IP datagrams, a host searches the ARP table for the MAC address corresponding to the destination IP address.
− If the ARP table contains the corresponding MAC address, the host directly sends the IP datagrams to the MAC address instead of sending an ARP Request message.
− If the ARP table does not contain the corresponding MAC address, the host broadcasts an ARP Request message to request the MAC address of the destination host.
Reverse Address Resolution Protocol (RARP)
If only the MAC address of a host is available, the host can send and receive RARP messages to obtain its IP address.
To do so, the network administrator must establish the mapping between MAC addresses and IP addresses on a gateway. When a new host must be configured, its RARP client requests the host's IP address from the RARP server on the gateway.