What is a broadcast storm and how does a broadcast storm occur?

The so-called broadcast storm, simply put, occurs when the broadcast data floods the network and cannot be processed, and occupies a large amount of network bandwidth, resulting in the failure of normal services to run, or even complete paralysis. A data frame or packet is transmitted to each node on the local network segment (defined by the broadcast domain) is broadcast; Due to the design and connection problems of the network topology, or other reasons, the broadcast is copied in a large number of network segments, propagating data frames, resulting in network performance degradation and even network paralysis, which is called a broadcast storm.

A broadcast storm is generatedAfter the broadcast packet is sent, the switch reads the frame header and finds that the target MAC is all F, so it sends it out from each port. The other switches receive the broadcast packets and send them again from each port, and then continue to send them until the switch crashes.

The main purpose of physically connecting switches into loops is to perform backup redundancy and prevent a switch from going down and causing the entire network to be paralyzed or an important network from being paralyzed. However, the ring network is prone to broadcast storms, and the spanning tree technique is introduced to prevent broadcast storms.

Broadcast:

Broadcasting refers to the means of disseminating news that transmits sound through radio waves or wires. A program that transmits a program through radio waves is called a wireless broadcast, and a program that transmits a program through a wire is called a cable broadcast. Radio was born in the 20s of the 20th century.

The advantages of broadcasting are that it has a wide range of objects, rapid dissemination, diverse functions, and strong appeal; The disadvantages are fleeting, sequential listening, no choice, and difficult to listen if you don't understand the language.

A bridge connects two similar networks and manages the flow of data over the network. It operates at the data link layer to extend the distance or range of the network and improve the performance, reliability, and security of the network.

After network 1 and network 2 are connected through the bridge, the bridge receives the packet sent by network 1, checks the address in the packet, and if the address belongs to network 1, it discards it, and conversely, if it is the address of network 2, it continues to send to network 2.

In this way, the bridge isolation information can be used to divide the same network number into multiple network segments (belonging to the same network number), isolate the secure network segment, and prevent users in other network segments from unauthorized access. Due to the segmentation of the network, each network segment is relatively independent (belongs to the same network number), and the failure of one network segment will not affect the operation of the other network segment.

Broadcast storm refers to a situation in which a large number of broadcast or multicast packets are sent by a node in a computer network, causing all nodes in the network to receive these packets and send them to other nodes, thus forming a cyclic and infinitely diffusing situation. Broadcast storms can lead to network congestion, wasted resources, and degraded performance, and in severe cases, network crashes. To solve the broadcast storm problem, the following aspects can be considered:

Optimize the network topology: By designing the network topology wisely, you can avoid problems such as loops in the network, which can effectively reduce the occurrence of broadcast storms.

Control the broadcast domain: You can set VLANs and subnets on the network to limit the scope of the broadcast domain and reduce the impact of broadcast storms.

Use broadcast suppression technology: The use of broadcast suppression technology can limit the range of broadcast packets and avoid the unrestricted delivery of broadcast packets, thereby reducing the occurrence of broadcast storms.

Use switches and other devices: Use switches and other devices to filter and control broadcast packets to avoid unrestricted delivery of broadcast packets, thereby reducing the occurrence of broadcast storms.

Troubleshoot in a timely manner: When a broadcast storm occurs, you need to troubleshoot the fault in a timely manner and take measures to solve the problem to avoid the expansion of the fault.

1. Broadcast storm.

Simply put, a broadcast storm occurs when broadcast data floods the network and cannot be processed, and occupies a large amount of network bandwidth, resulting in normal services being unable to run or even completely paralyzed.

A data frame or packet is transmitted to each node on the local network segment (defined by the broadcast domain) is broadcast; Due to the design and connection problems of the network topology, or other reasons, the broadcast is copied in a large number of network segments, propagating data frames, resulting in network performance degradation and even network paralysis, which is called a broadcast storm.

Second, the solution.

1. Check whether the network device used is a switch, if not, replace the correct switch, and remember not to use the hub.

2. Use MRGT and other traffic viewing software to view the ports that have a short circuit, and if the switch is manageable, you can also process and find the faulty network cable by closing the ports one by one. Once you find the short-circuited network cable, replace it with one of them.

3. Enable the tree generation protocol at the access layer, or turn on the tree generation protocol when diagnosing faults, so as to assist in determining the fault point. When a broadcast storm occurs, you should first understand the network changes before the failure, and establish a complete network documentation, including: network wiring diagram, IP address and MAC address correspondence table, etc., which can be scanned and obtained through LAN tool software.

4. The jumper used for cascading switch should be marked with some special marks, and it is best to choose to use different color jumper cords to distinguish them from other ordinary jumpers.

5. Other normal computers can be connected to the problematic port, if the fault is solved, it is caused by the damage of the original computer's network card or network failure, and the new network card can be replaced and the line and network configuration can be detected.

If the fault persists, it means that the network card of the original computer is not damaged, it may be that the port of the switch has been damaged, check the indicator light of the port, if it is confirmed that the port is damaged, the switch should be repaired in time or the computer should be connected to other ports, pay attention, do not repair the switch without authorization, otherwise the damage to the switch will outweigh the loss.

6. Install anti-virus software for each computer and configure the patch server (WSUS) to ensure that all computers in the LAN can be patched with the latest patches in time.

Regarding the meaning of broadcast storm control, the computer jargon is explained.

The device supports broadcast storm control, limiting the number of consecutive broadcast packets on each port, each broadcast packet is stored in the buffer and then one by one to other ports, when the number of stored packets exceeds 64, the device will drop the successive broadcast packets.

Simply put, a broadcast storm refers to the fact that the entire broadcast domain is flooded with a large number of broadcast packets, and new broadcast packets are constantly generated, which cannot be processed by network devices, and occupies a large amount of network bandwidth and system resources of network devices, resulting in business failure to operate normally or even complete paralysis.

Solution: 1. Install the WSUS patch server in the LAN to ensure that all computers in the LAN can be updated with the latest patches in time.

Second, it is best to install the network version of the anti-virus server in the local area network, if unconditional, at least to ensure that the virus database of the stand-alone version of the anti-virus software is updated frequently.

3. Check each computer's network card, network cable, and every port of the switch to check whether there is a fault.

Fourth, when a broadcast storm occurs, it is a good way to observe the indicator light of the switch to directly observe the network connectivity.

5. Since broadcast packets cannot cross network segments, VLANs are generally divided to suppress the generation of broadcast storms. VLAN division can be configured on Layer 3 switches. It can also be configured on the gateway device firewall appliance.

Broadcast

storm）

A broadcast storm occurs when the host system responds to a packet that is constantly circulating over the network, or when it attempts to respond to a system that does not respond. In general, in order to change this state, a steady stream of requests or response packets is generated, which often makes the situation more difficult. As the number of packets on the network increases, congestion can follow, slowing down the performance of the network to the point of paralyzing.

A data frame or packet is transmitted to the local network segment.

defined by the broadcast domain) is a broadcast; Due to the design and connection problems of the network topology, or other reasons, the broadcast is copied in a large number of network segments, propagating data frames, resulting in network performance degradation and even network paralysis, which is called a broadcast storm.

In fact, broadcast storms mostly appear in the LAN connected by hub and ring connection, if routers and switches are used, because routers and switches are designed with tree connections, they can effectively prevent broadcast storms.

But on the backbone, the main role of the router is routing. A router on the backbone must know the path to all the underlying networks. This requires maintaining a large routing table and reacting as quickly as possible to changes in connection status.

A malfunction of the router will cause serious information transmission problems. Within a campus network, routers are primarily used to separate subnets. With the continuous expansion of network scale, LAN has evolved into a campus network composed of multiple subnets connected by high-speed backbones and routers.

The subnets are logically independent, and the router is the only device that can separate them, which is responsible for packet isolation and broadcast isolation between subnets, and the router at the border is responsible for connecting to the upper network.

Solution. 1. Effectively divide the large network, so that the broadcast packet is only transmitted within a limited range.

2. Use the gateway to sort the data packets.

3. Use a router to isolate different subnets.