Cisco DPA 7600 Series Gateways

Field Notice: Fast Ethernet Link Flaps Between DPA76XX and Catalyst 3550, 2950, 3750 and 3548XL

May 17, 2004

Products Affected




Problem Description

When a DPA76xx is connected to a Catalyst 3550, 2950, 3750 or a 3548XL switch, the Fast Ethernet port can not maintain 100 Meg link negotiation.


The issue is believed to be due to a subtle PHY level incompatibility between the PHY device in the DPA76XX and the PHY devices used in the various switches.

Problem Symptoms

Symptoms include:

  1. Continuous Link flap messages on both Catalyst switchport and DPA76XX. Link is never established. Occurs during warm and cold start of DPA.

  2. "Ethernet failed to start" message on DPA76XX. Link does not come up. This occurs during warm and cold start of DPA.

  3. Link will come up, but ethernet link will randomly go down and back up.

  4. When link is up "Restart" menu command from DPA76XX will cause symptom number one to occur. Powering off/on switch will cause link to come back up but over time symptom three will occur.

Tested configurations:

  1. Both devices configured for 100/Full. One of the above symptoms will occur.

  2. Both devices configured for Auto/Auto. One of the above symptoms will occur.

  3. Both devices configured for 100/Half. One of the above symptoms will occur.

  4. Both devices configured for 10/Full. Link established.

  5. Both devices configured for 10/Half. Link established.


Configure the switchport for 10 megabytes full duplex.


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CSCec56705 (registered customers only)

ethernet link flaps between DPA7610 and 3550

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

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