Provider (P) Router in IP MPLS Network

[abdul.qadir5001]

Can we design a MPLS network without a Provider (P) router. If there is no Provider (P) router then how labels swapping will be performed?

[Julio E. Moisa]

Hi,

Yes you can, but all the routers should work as PE, it will be seen in a small lab mostly, connecting PE with PE and using OSPF internally for example but it is not scalable and suggested, in the most of the case the ISP´s MPLS networks are huge and the P routers are part of their core network. By design a MPLS network without P routers should not be a good practice taking in consideration many factors, security, cpu utilization, scalability, resources, etc.

Regards.

[abdul.qadir5001]

So if there will be no Provider (P) router so no labeling swapping will be? Only we have label push and pop process in MPLS Network?

[Julio E. Moisa · Accepted solution]

Yes you will have labeling swapping, remember the PE and P have the same configuration about MPLS basically but PE has MPBGP and the client routing protocol as well, you will be using OSPF or IS-IS internally and it will enable the exchange of labels, I have created a mini lab with 3 routers:

R4(CLIENT) ---- R2(PE) ---- R1(PE) ---- R3(PE)  (no full mesh)

R1#show mpls forwarding-table
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or Tunnel Id Switched interface
16 Pop Label 2.2.2.2/32 638 Et0/0 10.0.0.2
17 Pop Label 3.3.3.3/32 756 Et0/1 20.0.0.3
R1#

R2#show mpls forwarding-table
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or Tunnel Id Switched interface
200 No Label 3.3.3.3/32[V] 0 Et0/1 192.168.1.2
201 No Label 192.168.1.0/24[V] \
0 aggregate/CLIENTE
202 Pop Label 1.1.1.1/32 0 Et0/0 10.0.0.1
203 Pop Label 20.0.0.0/24 0 Et0/0 10.0.0.1
204 17 3.3.3.3/32 0 Et0/0 10.0.0.1
R2#

R3#show mpls forwarding-table
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or Tunnel Id Switched interface
300 Pop Label 1.1.1.1/32 0 Et0/0 20.0.0.1
301 16 2.2.2.2/32 0 Et0/0 20.0.0.1
302 Pop Label 10.0.0.0/30 0 Et0/0 20.0.0.1
R3#

R3#SHOW IP ROUTE VRF CLIENTE

Routing Table: CLIENTE
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR

Gateway of last resort is not set

4.0.0.0/32 is subnetted, 1 subnets
B 4.4.4.4 [200/11] via 2.2.2.2, 00:00:02
B 192.168.1.0/24 [200/0] via 2.2.2.2, 00:00:58
R3#

You can see the forwarding table of each one.

Regards

[abdul.qadir5001]

Dear Julio E.Moisa Thank you very much for such a great explanation 

[Julio E. Moisa]

Thank you Abdul, it was a pleasure, have a great weekend.

Regards