Re: Weired question - same DOT1Q tag on two interfaces on same

Assuming direct links between devices. The routing should work.

Please correct me if I understand it wrong.
A packet arriving on R2 from R1 will remove the L2 frame, do a L3 IP lookup,
forward the packet to the exit interface, where a new L2 frame will be
encapsulated.
Regardless if using the same vlan-id. on the ingress and egress interface.
Remember the interface function as L3 not L2.
The command "encapsulation dot1q 10" is a L2 interface encapsulation.
The routers are not partaking in any STP.
I have not labbed it, but I can see any problems :)

But this is not going to provide the solution to your customers problem.
Traffic is only segregated on the link, with the purpose to use one link for
many.
Routing will still exist between the clients, with one routing-table per
router.

Like Brad suggested... :)

HTH

On Wed, Apr 14, 2010 at 5:05 PM, Radioactive Frog <pbhatkoti_at_gmail.com>wrote:

> Folks,
> Here is what I am trying to do.
>
> all routers are 2911 or 2811 with routed interface (no switching module
> ESW).
>
> R1------------R2----------R3----------R4
>
> Scenario1 - which I always implement:
> -----------------------------------------
> R1 - R2 = VLAN 10 - 10.10.10.1/30
> R2 - R3 = VLAN 20 - 20.20.20.1/30
> R3 <http://20.20.20.1/30%0AR3> - R4 = VLAN 30 - 30.30.30.1/30
>
> Number of VLANs consumed in above scenario:
> R1 = 1 i.e. fast0/0.10
> R2 = 2 i.e. fast0/0.10 and fast0/1.20
> r3 = 2 i.e. fast 0/0.20 and fast0/1.30
> and so on......
>
>
> To reduce the number of VLAN per router and keep the routing intact can we
> do this?
>
> Scenario#2
> R1 - R2 = VLAN 10 - 10.10.10.1/30
> R2 - R3 = VLAN 20 - 20.20.20.1/30
> R3 <http://20.20.20.1/30%0AR3> - R4 = VLAN 30 - 30.30.30.1/30
>
> Number of VLANs consumed in above scenario:
> R1 = 1 i.e. fast0/0.10
> R2 = 1 i.e. fast0/0.10 and fast0/1.10
> r3 = 1 i.e. fast 0/0.10 and fast0/1.10
> and so on......
>
> Did you noticed in above case R2 and R3 are only using 2 VLAN ID.
>
> I'd be interested to hear from you guys if you see any issue in there i.e.
> using vlan id 10 on R2/R3 both fe0/0 and 0/1 interfaces.
>
> Note; No briding, need routing and shoudl be able to use all IOS Feature.
>
>
> The idea is in multi tented environment, we should be able to use vlan ID
> 10
> for a CUSTOMER1 on all the routers. Having vlan10 on R1 and 20 on r2-r3 and
> so on is a bit messy. This approach can also save number of vlan consumed
> and can tanent more customers.
>
> I went thr the Dot1q header but not sure how router treat this on
> interfaces.
>
> http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gtunvlan.html
>
> Anyone running this kind of single VLAN in a production environment?
>
> -frog
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
>
>
>
>
>
>
>

-- 
<ruhann>
www.routing-bits.com
Blogs and organic groups at http://www.ccie.net