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auto negotiation problem 10/100/1000 on c4506e WS-X4748-RJ45V


after updating J179 avaya phones we have massive problems with autonegotiating:
phones and switchports are 1000Mbps capable but but because of lack of cable infrastructure in some cases we use cable-sharing and so we only can use 2-pair ethernet.

First question: is this configuration supported bei IEEE?
Second question: is this problem an only avaya problem, because before update of phone software everything worked with no problem.

With autonegotiation for speed und duplex ports are flapping acout every minute. The only "working" conguration ist speed 100 und duplex auto. But in this case phone switches to full duplex und switchport to half duplex.

catalyst runs with this image:
System image file is "bootflash:cat4500e-universalk9.SPA.03.08.09.E.152-4.E9.bin"

Switchports are configures in this manner:

interface GigabitEthernet5/47
switchport access vlan 111
switchport mode access
switchport voice vlan 112
switchport port-security maximum 2
switchport port-security violation shutdown vlan
switchport port-security mac-address sticky
switchport port-security
speed 100
no cdp enable
flowcontrol receive off
flowcontrol send off
no lldp med-tlv-select power-management
spanning-tree portfast edge
spanning-tree bpduguard enable
ip dhcp snooping limit rate 15

Best regards

1 Accepted Solution

Accepted Solutions

Leo Laohoo
Hall of Fame
Hall of Fame
5 Replies 5



  - Start by verifying if these problems persist if (a) standard ethernet (cable) is used ; if not then you know the cause....


-- ' 'Good body every evening' ' this sentence was once spotted on a logo at the entrance of a Weight Watchers Club !

Leo Laohoo
Hall of Fame
Hall of Fame
speed auto 100

Thanks, it works. This will limit autoneg to max. 100 Mbps?


The command means "auto negotiate to 100 Mbps only".

OK. It works fine and we will use this in these cases.

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