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Chapter 36: VLAN Commands
Configuring VLAN Interfaces
switchport
ingress-filtering
C
U
OMMAND
SAGE
If a port or trunk has switchport mode set to access, then only one
•
VLAN can be added with this command. If a VLAN list is specified, only
the last VLAN in the list will be added to the interface.
A port, or a trunk with switchport mode set to hybrid, must be
•
assigned to at least one VLAN as untagged.
If a trunk has switchport mode set to trunk (i.e., 1Q Trunk), then you
•
can only assign an interface to VLAN groups as a tagged member.
Frames are always tagged within the switch. The tagged/untagged
•
parameter used when adding a VLAN to an interface tells the switch
whether to keep or remove the tag from a frame on egress.
If none of the intermediate network devices nor the host at the other
•
end of the connection supports VLANs, the interface should be added to
these VLANs as an untagged member. Otherwise, it is only necessary to
add at most one VLAN as untagged, and this should correspond to the
native VLAN for the interface.
If a VLAN on the forbidden list for an interface is manually added to
•
that interface, the VLAN is automatically removed from the forbidden
list for that interface.
E
XAMPLE
The following example shows how to add VLANs 1, 2, 5 and 6 to the
allowed list as tagged VLANs for port 1:
Console(config)#interface ethernet 1/1
Console(config-if)#switchport allowed vlan add 1,2,5,6 tagged
Console(config-if)#
This command enables ingress filtering for an interface. Use the no form to
restore the default.
S
YNTAX
[no] switchport ingress-filtering
D
S
EFAULT
ETTING
Disabled
C
M
OMMAND
ODE
Interface Configuration (Ethernet, Port Channel)
C
U
OMMAND
SAGE
Ingress filtering only affects tagged frames.
•
If ingress filtering is disabled and a port receives frames tagged for
•
VLANs for which it is not a member, these frames will be flooded to all
other ports (except for those VLANs explicitly forbidden on this port).
– 1089 –
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