SPOTO expert tells you MPLS Network Configuration on GNS3

MPLS is the significant parts of the SPOTO CCIE RS 400 101 lab exam.  However, some candidates found that it's difficult to master MPLS, SPOTO candidates passed these parts of the CCIE RS Lab exam easily. More info can be found in SPOTO Cisco WhatsApp study group.


What is MPLS (Multi-Protocol Label Switching)?

MPLS is lable base fast switching, MPLS is a technique which forward the packets in the network on bases of labels.



Router use the process switching in which whenever router received a packet it checks its IP address match with routing table and forward packet, send ARP request for MAC addres. This Process become a little slow when router dealing with a lot of IP packets, in case of VOIP e.g. a IP-Phone call may using 50packets/second then router have to perform process switching for every packets  

But in MPLS instead of processing above large packet each time route just use a label to forward a packet which saving some processing cycle and made fast forwarding.

MPLS Configuration on GNS3:


Design above lab in gns3 and configure IP address and EIGRP according to EIGRP configuration on GNS3 . In our lab R3 is provider router where as R2, R4 and R5 are the provider edge routers.

On Cisco router to enable the MPLS you required to :

1.Enable CEF(cisco express forwarding) on router

2.Change MTU (maximum transmission unit) from 1500 to 1512 on MPLS enabled interfaces, becase MPLS header is of 4 bytes and one interface have maximum of three.

R2 MPLS configuration Commmands:

R2#conf t

R2(config)#ip cef

R2(config)#int s1/1

R2(config-if)#mpls label protocol ldp

R2(config-if)# mpls ip

R2(config-if)# mpls mtu 1512

R2(config-if)#ip route-cache cef


R3 MPLS configuration Commmands:

R3(config)#ip cef

R3(config)#int s1/1

R3(config-if)#ip route-cache cef

R3(config-if)#mpls mtu 1512

R3(config-if)#mpls ip

R3(config-if)#mpls label protocol ldp

R3(config-if)#int s1/2

R3(config-if)#mpls mtu 1512

R3(config-if)#ip route-cache cef

R3(config-if)#mpls ip

R3(config-if)#mpls label protocol ldp

R3(config)#int s1/0

R3(config-if)#mpls mtu 1512

R3(config-if)#ip route-cache cef

R3(config-if)#mpls ip

R3(config-if)#mpls label protocol ldp


R4 MPLS configuration Commmands:

R4(config)#ip cef

R4(config)#int s1/0

R4(config-if)# mpls ip

R4(config-if)#mpls label protocol ldp

R4(config-if)# mpls mtu 1512


R5 MPLS configuration Commmands:

R5(config)#ip cef

R5(config)#int s1/0

R5(config-if)# mpls label protocol ldp

R5(config-if)# mpls ip

R5(config-if)# mpls mtu 1512


R5(config-if)#ip route-cache cef


MPLS Verification Commands:


R3#show mpls ldp neighbor

R3#show mpls forwarding-table

R3#show ip cef 

R3#sh mpls ip binding

More you may be interested:

MPLS Overview (part one)

MPLS Overview (part two)

CCIE SP Written Exam Practice Questions


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