Why Can I Remotely Connect to an ECS But Cannot Ping It?


To successfully ping an ECS, enable Internet Control Message Protocol (ICMP) in the security group rules for the ECS.

Other related questions:
Intermittent ping interruption on S series switch
If an S series switch fails to be pinged intermittently, check whether ICMP packets are discarded by CPCAR. - If ICMP packets are discarded by CPCAR, ping packets cannot be sent to the CPU. In this case, modify the CPCAR value of ICMP packets. Note: An improper CPCAR setting will affect services on your network. It is recommended that you contact Huawei technical support personnel before adjusting the CPCAR setting. -If ICMP packets are not discarded by CPCAR, run the undo icmp rate-limit enable command to disable ICMP rate limit. Then check whether forwarding information for ping packets, such as the returned route, exist on the switch.

How to locate the ping failure
When the ping operation fails, locate the fault based on the following troubleshooting roadmap: 1. Check whether the AR interface is Up and whether the IP address is configured correctly. Command: display interface brief and display ip interface [ < interface-type > < interface-number > ] 2. If a Layer 2 interface is used, check whether STP is running on the AR and check whether the physical interface where ping packets pass is blocked. Command: display stp [ instance < instance-id > ] [ interface < interface-type > < interface-number > ] [ brief ] 3. Check whether routes are reachable: If routes are unreachable, troubleshoot the fault. Command: display ip routing-table 4. Check whether policies are configured on local and remote devices. If the remote device is a firewall, check whether the remote interface is added to a zone and whether the inter-zone rule is enabled. 5. Check whether ARP entries of the direct route are learned correctly. If ARP entries cannot be learned, check whether strict ARP learning is enabled. Disable strict ARP learning and try again. If the fault persists, perform the ping operation on one device and check whether ARP request packets are sent out from the interface and whether the remote device sends ARP reply packets based on ARP packet statistics. Commands: display arp and display arp learning strict 6. If there is no preceding problem, collect statistics on ICMP packets, determine the position where packets are lost and locate the packet loss point.

Termination sub-interfaces that connect two devices cannot ping each other. Why
After you configure IP addresses for termination sub-interfaces that connect two devices, they cannot ping each other. Check whether you have run the arp broadcast enable command on the interfaces. If this command is not run, the devices fail to send ARP Request packets through these interfaces and cannot learn ARP entries. By default, the arp broadcast enable command is disabled in V200R003C00 and earlier versions and enabled in V200R003C01 and later versions.

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