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setting vlan routing on routers

carl_townshend
Spotlight
Spotlight

Hi all, Do I have to give the physical interface an ip on my router, or can I use no ip address and just put the subinterface ip addresses on there ?

2 Replies 2

royalblues
Level 10
Level 10

Hi Carl,

When you use subinterfaces the IP address are assigned to the subinterface and not to the physical interface.

eg.

interface fastethernet 0/0

no ip address

speed 100

duplex full

interface fa 0/0.1

ip address 10.10.10.1 255.255.255.0

encapsulation dot1q 1

interface fa 0/0.2

ip address 20.20.20.1 255.255.255.0

encapsulation dot1q 2

In case of serial interfaces, the encapsulation types are defined on the main interface and the ip address is configured on the sub-interface

eg

interface Serial0/0/0:0

no ip address

encapsulation frame-relay IETF

frame-relay lmi-type ansi

!

interface Serial0/0/0:0.1 point-to-point

bandwidth 1024

ip address 30.30.30.1 255.255.255.252

frame-relay interface-dlci 283 IETF

HTH, rate if it does

Narayan

mark.edwards
Level 1
Level 1

yes, the main interface can be ip unnumbered. just put IP address on subinterface and remember to configure the trunk encapsulation and the VLAN under the subinterface.

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