Switch not obtaining management IP beyond Router

[callen15]

Hello, I have two switches, SW1 and SW2 as well as an ISR router. I have a subinterface on the router (g0/0/0.2) that I've given an IP through DHCP on VLAN 2.  g0/0/0.2 is connected to SW1 via Trunk port. My secondary router interface (g0/0/1) has a subinterface, (g0/0/1.2) I'm wanting to give SW2 a management IP from VLAN2. How would I go about making this work?

Forgot to add: VLAN 2 is the native on the trunked port connecting to g0/0/0.2. We host in DHCP server in that subnet that gives out the 10.4.1.0/24 addresses for management. 

[Reza Sharifi]

Hi,

Usually, it is not possible to assign IPs from the same subnet to 2 different sub-interfaces. For that to work, you may want to look at IRB.

See document for config example:

https://www.cisco.com/c/en/us/support/docs/lan-switching/integrated-routing-bridging-irb/17054-741-10.html

HTH

[balaji.bandi]

Not sure what is the use case here, if you have 1 router, you need to have 2 exit paths, you already have one, why do you need another IP address on the same subnet on another interface?

[callen15]

I wanted my second switch (the one connected to g0/0/1) to obtain a management IP (10.4.1.0/24) from VLAN2. Analogous to how one would connect a trunk port on one switch to another trunk on a different switch and pass VLAN info and use the native VLAN to hand out a management IP via DHCP

[paul driver · Accepted solution]

Hello

try the following to bridge the rtrs two interfaces so to allow communication between the two switches.

rtr < 

bridge irb
bridge 2 protocol ieee
bridge 2 route ip

interface x/0
interface x/0.2
encapsulation dot1Q 2
bridge-group 2

interface x/1
interface x/1.2
encapsulation dot1Q 2
bridge-group 2

interface BVI2
ip address x.x.x.x y.y.y.y