Isis areas -vlan plan

[anand kumar]

Hi Guys,

I know that level 2 routers learn about paths both within areas and between areas.

If that is so , can we repeat the vlans that are in area 1 to the area2 ,i.e excluding the vlans that are directly connected.

[Peter Paluch]

Hello,

I believe you are confusing two things together. To a routing protocol, a VLAN is a Layer2 technology just like any other interface, be it Token Ring, PPP, ATM, Frame Relay, etc. Just like a router's interface terminates a particular Layer2 technology on the router and does not allow it to transparently pass further, a router also terminates a VLAN without allowing it to pass further. So regardless of IS-IS, its levels and areas, VLAN numbers on different interfaces of routers can be reused, even on a single router. So for example, this configuration is perfectly valid:

interface FastEthernet0/0
 no shutdown
!
interface FastEthernet0/0.10
 encapsulation dot1q 10
 ip address 10.0.10.1 255.255.255.0
!
interface FastEthernet0/0.20
 encapsulation dot1q 20
 ip address 10.0.20.1 255.255.255.0
!
interface FasthEthernet0/1
 no shutdown
!
interface FastEthernet0/1.10
 encapsulation dot1q 10
 ip address 10.1.10.1 255.255.255.0
!
interface FastEthernet0/1.20
 encapsulation dot1q 20
 ip address 10.1.20.1 255.255.255.0

What can not be reused are the IP address spaces - they have to be unique across the entire routed internetwork, regardless on their placement in areas or Layer2 technologies.

Please feel welcome to ask further!

Best regards,

Peter

[anand kumar]

Hi All,

Thanks Peter for the clarification.

The topology is like the attach, we have to terminate mpls pseudowire

from DX to the 2 AX,i.e AX1 & AX2 over this ISIS network;

could it be possible like as mentioned in diagram.

Regards

Kumar