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FAQ ID # 137
Last Update : 2012/02/20
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Question / Issue
My first few PING's timeout or take several seconds to reply.

Answer / Solution


The first few PING (ICMP) packets sent from computers on the Internet to the LAN-Cell's (or PocketPORT's)  cellular modem's WAN IP address either timeout or take several seconds to be acknowledged.


This is normal behavior on certain cellular networks and certain modem cards.  To conserve resources, some cards and networks put their connections into a "dormant" state if no active traffic is being transmitted.  The first packets sent or received will take the connection out of dormant state, but this process can take several seconds and may result in dropped ping's or very slow responses.

Actions you can take:

  1. Check with your modem card manufacturer to see if they support a configuration command to disable the inactivity (dormancy) timer.
  2. Check with your cellular carrier to find out what their dormancy timer settings are.
  3. Use the LAN-Cell or another device to periodically generate packets to prevent the connection from entering the dormant state. (See WAN Continuity Check / AutoPing)
  4. Adjust your application software to be tolerant of lost packets and/or high packet latency.

If you're getting no response at all from your PING's, check with your carrier to see if they are blocking inbound ICMP packets to your account (or the APN you are connecting to).  Some carriers require special configuration of your account to enable response to ICMP requests (or other in-bound traffic).

Related FAQs
How do I "ping" a device attached to the LAN-Cell from the Internet?

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