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Long Delay for Manually Switching NX112 Switch Modules in Smart-Link

Publication Date:  2015-06-25 Views:  76 Downloads:  0
Issue Description
Hardware configuration:
E6000 server
NX112 switch module (electrical port card)

Symptom:

Services are interrupted for a long period when NX112s are manually switched in Smart-Link.
Handling Process
Figure 1 shows the test environment.

Figure 1 Test environment



Four server blades (CNA141, CNA142, CNA143, and CNA144) are in Smart-Link. Two network ports (eth0 and eth1) of each server blade are connected to switch modules A1 and A2, and the two modules are connected using a stack cable. Table 1 describes the connections.

Table 1 Connections 



Test process:

The network is connected, and the Smart-Link switching function is enabled. After the Master (Trunk 0) link is interrupted, Trunk 1 is in active state, and Trunk 0 is in inactive state. In this case, networks over Trunk 1 are normal. After three seconds the Master link is restored, Trunk 0 is in active state, and Trunk 1 is in inactive state; however, the network cannot be pinged. Based on the default configuration for Smart-Link, the service interruption duration is three seconds during link switchover; however, service interruption lasts for three to four minutes after links are switched back.
Root Cause
When links are switched in Smart-Link, the original forwarding entry is not applicable to a new topology network. MAC entries and ARP entries need to be updated on the entire network. Meanwhile, Smart-Link sends Flush packets for instructing other devices to update MAC entries and ARP entries. However, Flush packets are not configured during Smart-link creation.

Flush packets cannot be sent, which causes the too long delay for manually switching NX112s in Smart-Link.

Solution
Enable the Flush packet sending function when configuring Smart-Link.

1.  Enter the following command to configure Smart-Link when enabling the Flush packet sending function:

flush send control-vlan 30 password simple 123

2.  Run the following command to configure eth trunk0 in the aggregation switch when enabling the Flush packet sending function:

Smart-link flush receive control-vlan 30 password simple 123

Run the following command to configure eth trunk1 in the aggregation switch:

Smart-link flush receive control-vlan 30 password simple 123

END