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3750/2950 switchport mode access and autonegotiation


can anyone tell me Cisco's recommendations for the following

1 cisco 2950T (c2950-i6k2l2q4-mz.121-22.EA7) connects into a 3750 (c3750-i5-mz.122-20.SE).

the link is switchport mode access. the config for the link on the 3750 is

switchport access vlan 171

switchport mode access

on the 2950 the link is configured as

switchport access vlan 171

the link works fine and when i check the link interfaces on both 3750 and 2950, its reported as being an access link. the question is - should i be using the same config at both ends (ie adding switchport mode access to the 2950)

2 same set up as above - link set for auto-negotiation and negotiates 1000 Full-Duplex. should i be specifying Speed/Duplex for the link and if so should both ends of the link be specified.

although the link works fine, i'd just like to make it bombproof .




Re: 3750/2950 switchport mode access and autonegotiation

Hello Andy,

The main difference between the two is that the first is explicitly configured in access mode ( ie can never become a trunk ). The other is a dynamic port that can transition into either access or trunk mode which depends on the configuration of the link partner.

For consistancy you can configure the switches identically.

interface FastEthernet0/1

description connected to switch xyz


switchport mode access

switchport access vlan 171

In case no configuration for speed and duplex exist, auto is the default. If you link supports gigabit ethernet on both ends, the switch will negotiate 1000-full. In case you want to make shure they negotiate speed and duplex to 1000-full, you specify it in interface configuration mode.

interface FastEthernet0/1

speed 1000

duplex full



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Re: 3750/2950 switchport mode access and autonegotiation

thanks leon

i'll duplicate the switchport/speed/duplex settings at both ends of link.


Re: 3750/2950 switchport mode access and autonegotiation

On Cisco 2950 the default port mode is dynamic desirable - it forms trunk with dynamic auto and trunk port onyl anyway it is in access mode, like in your case.



Please rate me if I helped.

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