December 29, 1999
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Revision Date Comment 1.0 29-DEC-1999 Initial Public Release
Products Affected C85FE-16T-16K= C85FE-16T-64K= C85FE-16TACL-16K= C85FE-16TACL-64K= C85FE-8T-16K= C85FE-8T-64K=
All ports on 10/100 EPAMs have auto-negotiation on by default in Cisco IOS® Software release 12.0(5)W5(13). This is a change from the previous release where these ports defaulted to 100/Full. This is described in the DDTS section below.
The Ethernet ports on the Catalyst 8500 family initially did not support auto-negotiation. In Cisco IOS release 12.0(4a)W5(11) auto-negotiation was added as a configurable setting on a per port basis. In the latest release, 12.0(5)W5(13), auto-negotiation was changed to be enabled on all ports as the default setting. This is a change from the previous default setting of 100/Full.
In the CSR 12.0(5)W5(13) software release auto-negotiation for speed and duplex is on by default. In the releases prior to this release, auto-negotiation was NOT supported by default. As a result, each connected interface had to be set to run in full duplex mode. If the customer upgrades to CSR 2.2 with the router running in forced full duplex mode, there will be performance issues. The symptoms include high collision rate, reduced throughput, and more packet drops. This is because the Catalyst 8500 will wait to auto-negotiate with the connected device. When the connected device is forced to run in full duplex mode it will not participate in auto-negotiation. This will cause the Catalyst 8500 interface to settle in half duplex mode, which causes a mismatch between the device and the Catalyst 8500 at the interface level. Defaulting to half duplex mode when the peer is incapable of negotiation is in accordance with the specification.
Possible workarounds are:
- Force the link to run in full duplex mode in 8500.
- Remove the full duplex command on the connected device (peer) side.
To follow the bug ID link below and see detailed bug information, you must be a registered customer and you must be logged in.
DDTS Description CSCdp39268 (registered customers only) Speed/Duplex default is changed to auto-negotiate with next release.
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