Cisco Application and Content Networking System (ACNS) Software

Understanding the Interaction Between the Content Router and Content Engine in ACNS 5.x.x

Document ID: 61071

Updated: Jan 31, 2006



This document provides information on Content Router (CR) and Content Engine (CE) interaction in Application and Content Networking Software (ACNS) 5.x.x. This document discusses the importance of the CE being able to communicate to the CR.



There are no specific requirements for this document.

Components Used

This document is applicable to ACNS 5.0 and above.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.


For more information on document conventions, refer to the Cisco Technical Tips Conventions.


Understanding CR/CE Interaction in ACNS 5.x.x

In ACNS 5.x.x, the CEs initiate communication to the CR. The CE's need to be able to reach the IP address that is listed for that CR in their database. The CR cannot be placed behind a firewall that blocks the CEs from making DNS queries to the CR.

The CEs make a keepalive to the CR to tell the CR that they are alive and can take requests. This is done when the CE makes a DNS request to the CR on port 53. This is only a keepalive, and is not for general name resolution. Usually, the CE has the corporate DNS server as its IP name-server (not the CR). You should see DNS requests to the normal DNS server on the CE, but you should also see requests to the CR approximately every 30 seconds.

Troubleshooting CR/CE Connectivity

The CEs should make a connection to the CR approximately every 30 seconds. Issue this command on the CR to verify that the CEs are communicating:

tcpdump port 53

The CR must show online on the CDM GUI. If the CR is not online, you need to determine why. Once online, wait for the CE to recognize that it is online (may take 6 minutes), plus an additional 30 seconds; you should see port 53 communication in the tcpdump command output.

These commands are useful for troubleshooting:

  • show content-routing summary — displays the summary statistics for all Websites in the CR simplified hybrid routing table.

  • show statistics content-routing dns — displays simplified hybrid content routing DNS statistics.

  • show statistics content-routing ce — displays simplified hybrid content routing of the specified CE.

Make sure that the coverage zone is configured correctly. Refer to Setting Up Content Request Routing in the ACNS Network for more information.

Related Information

Updated: Jan 31, 2006
Document ID: 61071