SUBCARD MISMATCH in DAP Board

Description

As Huawei OTN OSN series support using NE as SDH, PTN, DWDM, OTN and POTN. we installed MUX/DEMUX MR8 and B1DAP amplifiers to better utilize the installed OSN 1800 V NEs, The DAP boards support 2 small slots each one can house an amplifier unit totally dependent of the unit in the other slot, but after installing the boards and Sub_boards ((OAC and OBC)) , An alarm raised (SUBCARD_MISMATCH) the alarm source is the DAP boards.

The alarm doesn’t affect services.

SUBCARD_MISMATCH

 

Procedures of Check 

1- first I checked the board software and hardware version with NE version, But I found that NE software is supporting boards and sub boards also.

 

2- By checking the alarm in the information center, it was mentioned that there is a problem with logical ports whether added wrongly or missed.

The logical  ports could be checked from the board panel, so I checked the DAP panel and found the TDC/RDC logical ports are added as 15 and 16  ports, The TDC/RDC number 15 is related to the 1st  slot in DAP board and The TDC/RDC number 16 is related to the 2nd slot in the DAP board.

 

RDC/TDC

-As known the TDC /RDC ports are intended for DCM (Dispersion Compensation Module) connection used in the OAC amplifier unit only, so the RDC/TDC unit should not be added for the subslot uses OBC unit.

- To check which kind of amplifiers are installed in the sunboards, I used the board Manufacturer report and found that 1st slot houses OBC unit and the 2nd slot is equipped with OAC unit.

 

Manufacturer Report

 

Solution 

As the OBC doesn’t need the logical ports of the RDC/TDC ,So I deleted them from logical ports number 15 in  the board panel and then the alarm cleared.

NTP (Network Time Protocol) - (S6720 Configuration)

NTP, or Network Time Protocol, is a network protocol widely used to synchronize the clocks of computers and other devices on a network. It plays a key role in maintaining time accuracy in computer systems and network communications, ensuring that different devices are synchronized with respect to a common reference time.

 

If a router has the wrong time, it can lead to several issues and complications in network operations and services. The accuracy of the time on a router is crucial for various network functions and security measures. Here are some problems that can arise if a router's time settings are incorrect:

Router logs and event timestamps may be inaccurate, making it challenging to troubleshoot network issues or identify security incidents. Accurate timestamps are essential for diagnosing problems and tracking events.

 

• Log and Event Timestamp Inaccuracy: Inaccurate timestamps in logs and events make troubleshooting difficult and hinder identifying the root causes of issues.
• Security Vulnerabilities: Incorrect router time can lead to security vulnerabilities, affecting authentication, encryption, and secure communications.
• Access Control Issues: Network access control systems may malfunction, leading to improper enforcement of access policies and permissions.
• Certificate Validation Errors: SSL/TLS certificates may fail validation, causing connectivity issues and security warnings.
• Authentication Failures: Authentication protocols relying on time-based elements, like RADIUS and TACACS+, may not function correctly.
• Logging and Compliance Violations: Non-compliance with regulations, like PCI DSS or HIPAA, due to inaccurate timestamps in logs and records.
• Backup and Restore Challenges: Backup and restore operations may become complicated, impacting data recovery and backup management.
• Network Synchronization Disruption: Inaccurate time settings can disrupt network synchronization, leading to inconsistencies across the network.
• Delays in Troubleshooting: Accurate timestamps are vital for troubleshooting network issues. Incorrect timestamps can cause delays in diagnosing and resolving problems.
• Event Correlation Difficulty: Event correlation becomes challenging without accurate timestamps, affecting the identification of the root causes of network problems.

 

 

How NTP works:

 

NTP Server Clock: A reference NTP server, usually called "stratum 0", has a high-precision clock, such as an atomic clock or GPS, which provides the precise time.

 

Server Hierarchy: NTP uses a hierarchy of servers to distribute time. Top-level servers (stratum 1) synchronize their clocks with accurate time sources, while lower-level servers (stratum 2, stratum 3, etc.) synchronize with higher-level servers.

 

Requests and Responses: Devices that want to synchronize their clocks send requests to NTP servers. NTP requests are short messages that include information about the current time of the device making the request.

 

Time Adjustment: The NTP server receives the requests and responds with time information, including the deviation between the server's time and the requesting device's time. The requesting device uses this information to adjust its local clock.

 

Adjustment Algorithm: NTP uses a sophisticated algorithm to calculate the travel time of the request between the device and the server and, based on this calculation, adjusts the clock of the requesting device to be closer to real time.

 

Server selection: Devices usually have several options for NTP servers from which they can synchronize. They select servers based on criteria such as the server's clock accuracy and network latency.

 

Continuous Monitoring: NTP also includes continuous monitoring mechanisms to adjust the clock as time passes, keeping it accurate.

 

The result of this process is a network of devices with synchronized clocks, which is essential for many aspects of computing and network communications. This is particularly important in applications that depend on accurate event records, such as security systems, financial transactions, telecommunications and even the precise synchronization of satellite systems and telecommunications networks. NTP helps ensure that all these operations take place based on a common and reliable time.

 

If we search the Internet we can find some servers that are available for use.

 

Now let's configure the IP of the NTP service on our S6720-30C-EI-24S-AC switch. I love this equipment!

 

 

Our NTP service will run on the Meth0/0/1 interface and on a vpn-instance named vrfMGMT.

 

 

Switch layer2 or layer3 which one to choose and why?

An Ethernet switch performs several tasks, including creating VLANs.  However, there are two types of switches: Layer 2 (L2) and Layer 3 (L3) and both are networking devices, but they operate at different layers of the OSI (Open Systems Interconnection) model and serve different purposes. 

First, a small summary about VLANs VLANs are like islands within a network. Equipment on one "island" does not have direct access to equipment on another. Thus, VLANs create isolation between parts of the network, even if the equipment is connected to the same switch.

 

However, sometimes it is necessary to have some communication between different VLANs. Either to access a server (communication between the users' VLANs and the servers' VLAN), or to access the Internet (communication between the users' VLANs and the Internet exit router). And these are just a few examples of applications where we may need to "interconnect" these "islands".

 

Here's a comparison of the Layer 2 and Layer 3 switchs:
 

Layer 2 Switch:
1. Operating Layer: Layer 2 switches operate at the Data Link Layer (Layer 2) of the OSI model.
2. Function: They are primarily responsible for forwarding Ethernet frames based on the physical MAC (Media Access Control) addresses of devices on the network.
3. Forwarding Decision: L2 switches make forwarding decisions solely based on MAC addresses, creating a table that maps MAC addresses to specific switch ports (MAC address table).
4. Local Segmentation: L2 switches are used to segment a LAN (Local Area Network) into smaller collision domains, reducing network congestion and improving network efficiency.
5. Limited Routing: L2 switches do not perform routing functions. They are unaware of IP addresses or higher-layer protocols, making them less suitable for routing traffic between different IP subnets or VLANs (Virtual LANs).

Layer 3 Switch:
1. Operating Layer: Layer 3 switches operate at the Network Layer (Layer 3) of the OSI model.
2. Function: They combine the capabilities of traditional Layer 2 switching with some routing capabilities.
3. Forwarding Decision: L3 switches make forwarding decisions based on both MAC addresses and IP addresses. They maintain a routing table to determine the best path for IP packets.
4. Routing Between Subnets: L3 switches can route traffic between different IP subnets or VLANs, effectively acting as routers. This makes them suitable for interconnecting multiple subnets within a network.
5. Advanced Routing: Some Layer 3 switches support advanced routing protocols like OSPF (Open Shortest Path First) or BGP (Border Gateway Protocol), allowing them to participate in complex routing scenarios.
6. Network Segmentation: L3 switches can create multiple VLANs and route traffic between them, enabling network segmentation for security, performance, and management purposes.
7. More Complex Configurations: Configuring and managing Layer 3 switches can be more complex than Layer 2 switches due to the additional routing functionality.

A managed L2 switch allows the creation of VLANs, but does not interconnect them. So, if I have a network made entirely of L2 switches, I can create VLANs, but I can't make them communicate. I can even use a router (which is also a Layer 3 equipment) to interconnect the VLANs, but normally a router is an equipment that has a low packet switching capacity, or - translating into Portuguese - a router can become a bottleneck in communication between VLANs.

 

An L3 switch, on the other hand, is a switch that is the same as an L2 switch (it has ports, creates VLANs, manageability, etc.) but it has a functionality that L2 switches do not have: it allows VLANs to be interconnected.

One comment before we continue: an L3 switch is a router. Many people think that a router is just the equipment that connects to the Internet. Is not true. A router is any device that connects different networks. Thus an L3 switch is also a router. So when I said above that "..but normally a router is a piece of equipment that has a low packet switching capacity..." I wasn't being 100% honest with you, reader. A router (the type that connects a network to the Internet) is normally a piece of equipment with a lower switching capacity. However, an L3 switch is a router, which is "inside" the L2 switch (that is, it does everything that an L2 switch does) and has greater capacity. Let us now return to our subject.

 

So, with an L3 switch, the network administrator can - in an organized way - communicate between the VLANs. It is important that I can have multiple L3 switches or just one L3 on my network, even though I have multiple L2 switches.

 

If I have one L3 switch and several L2 switches, that L3 switch is typically the central switch. All inter-VLAN traffic passes through it.

 

If I have several L3 switches, the cost of my project is greater and also the configuration complexity is greater. However, with several L3s I share my load, so I can have better performance in the interconnection between VLANs.

 

Nowadays, most projects aim to connect users' VLANs with the servers' VLAN and the Internet, and nothing else. In other words, nowadays most projects do not need large arrays of L3 switches: several L2 switches connected to a central L3 switch (or if I want redundancies, connected to two central L3 switches) is enough for the vast majority of the projects.

 

Choosing Between L2 and L3 Switches:

Use L2 Switches When:
• You need basic Ethernet frame switching within a single VLAN or subnet.
• Network segmentation at the IP layer is not required.
• You want a simple and cost-effective solution for LAN connectivity.
 

Use L3 Switches When:
• You need to route traffic between different IP subnets or VLANs.
• Advanced routing features like OSPF or BGP are required.
• You want to create a more secure and segmented network.
• You need efficient routing within your LAN, especially in environments with heavy inter-VLAN traffic.
 

 

In practice, many modern network switches are capable of both Layer 2 and Layer 3 operations, allowing network administrators to choose the appropriate mode based on their specific requirements. These switches are sometimes referred to as "multilayer switches." The choice between L2 and L3 switches depends on the complexity and goals of the network design.

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