Unidirectional Link Detection Mode To Eliminate The Switch Error Diagnosis

By Author: ann li
Total Articles: 3
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A, what circumstances would be Quidway S5700 Quidway S5700 mistaken diagnosis?
False diagnosis of the situation is even when a link or switch port indicating lamp is normal (i.e. the port state is UP), but still not normal transmission of data traffic interface. Usually the error is called unidirectional links. Under normal circumstances, when there is the interface failure, software failure, hardware failure or other abnormal reasons, this error will occur. With current technology, the switch is not fundamentally to avoid such mistakes. Therefore only by other means, to strengthen the detection of the switch port, as soon as possible in order to find this error. In Cisco series switches, it uses UDLD model to solve the error diagnosis of this condition.
UDLD theory, which is in the second layer protocol. But from a practical point of view, it often has a deep relationship with the first layer content. That is to say, the UDLD mode does not light in the second layer of operation, the relevant mechanisms will be with the first layer of cooperative ...
... work, to complete the. The main idea is to UDLD protocol running between the first, two, finally determine the actual working state of the link. When found to have "link UP is normal, but no transfer flow" of the agreement, UDLD will immediately alert.
Specifically, in the first layer through the automatic negotiation function to observe the physical parameters such as operation related signaling. While UDLD protocol will perform some automated negotiation mechanism is not able to perform the task. Let the automatic negotiation found physical signaling have abnormal time, does not automatically add the port conversion from UP state to other states, which leads to the failure of unidirectional link. The UDLD protocol can accept from the automatic negotiation mechanism transfer to the parameters, and then find the fault timely will switch port is closed. Visible, the UDLD model is not only a kind of protocol, but UDLD protocol and the result of the interaction of automated negotiation mechanism. If the network administrator to start the UDLD mode, then must also enable UDLD protocol and the automatic negotiation mechanism, in the first layer and the second layer through the work of the Secretary, collaborative them, to prevent physical or logical connection, thereby eliminating the error diagnosis switch fundamentally.
Network administrators need to understand is, complement UDLD and diagnostic system is not switch the original, but an independent diagnostic method. That is to say, it is the running state of each port of the switch from another angle self diagnosis. No basically conflict or overlap between the two. In practice, the traditional diagnostic methods and UDLD model is often used at the same time.
Two, the rational allocation of various parameters under UDLD mode
If you enable UDLD protocol and the automatic negotiation mechanism, started the UDLD model, in this case, an interface switch regularly to the nearby port of UDLD datagram. Under normal circumstances, the interface switch before a predetermined timer expires receives a response packet. If before the timer expires, the switch sends a UDLD packet interface also does not receive the response information, the UDLD protocol will think a fault, that is a fault with unidirectional links (in fact more precisely, should be automated negotiation found this fault and inform the UDLD protocol). When UDLD know the situation after, will immediately shut down the switch interface problem.
When the UDLD configuration, first of all need to consider this timer. That is to say, the time is set as. If the set time is short, not only will cause data flow is not necessary, but also possible because of data delay in not in a reasonable time receive a response packet. But if the timer setting time is long enough, you may not be able to find problems in a short period of time. You know, maybe a minute for users, not much feeling. But for the data transmission network, the time is long. By default, this timer of 15 seconds.
In practical work, the network administrator may need according to the different situation to set this parameter. Such as the need for complex situation, according to the length of the enterprise network cabling to consider. According to the previous situation, enterprises may often encounter network jam and so on, and this blockage is temporary, so appropriate to extend this timer etc.. The author of the proposal is in the beginning of the timer can be set a little longer, and then slowly. Finally get Huawei Quidway S5700 Huawei Quidway S5700 a reasonable numerical.