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10/100 Ethernet management port


Could someone please explain me the function of the "RJ-45 10/100 management port" on new switches (4948, 3750x3750E, 3650E, ,2960s, Nexus etc..)

Cisco Documentation suggests it's "OOB Ethernet port" but I am slightly puzzled with regards to the function of the port especially for L2 switches. Because it’s only one port what if I lost connectivity to that port? I will lose management connectivity to the switch..

Traditionally mgmt VLAN was extended across to all the switches and SVI interface controls Mgmt access so even if physical port is down SVI interface will stay up and Mgmt VLAN will be usually trunked so visibility to the switch will not be affected.

I appreciate if someone please explain me the purpose and benefit of using Mgmt port against SVI interface for management



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10/100 Ethernet management port


The OOB management interface is a 10/100 Ethernet port on 2960's. The OOB port is referred to as "Fa0" in the switch and is a Layer 3 interface. The Fa0 interface must have an IP address assigned in order to function.

You need to have a physical connection and assing IP address to this port in order to function as expected, If the physical connectivity to this port itself is down then the SVI will be down (up down state)

If you are using this port as a uplink from other or to other switches then you will loose access.

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Re: 10/100 Ethernet management port


Security and managability.

OOB = Out of band

Security reasons

Fx if you have a policy that states that you are not allowed to control the switches over the "normal" network

in this context it is just a added layer of security.

(not sending login information over the normal network and not able to connect to the switch over the normal network only the special management network)

Personally I will send syslogs/snmp and such information over the management, but have not tested it yet.

Management reasons

Fx if you have a problem with the network (saturated links/broken links) the link going to the special management port will not be affected and you can control and make the apropriate changes to the switch through the management port even if the network itself is saturated.

just 2 examples and there are many more

just do not make the mistake to connect the port to a switchport in the front of the switch, then it will have lost its function.

good luck


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