Earning your Cisco CCNA and CCNP is a thickened proposition, and conception of that is the fact that you apace wager that theres commonly more than digit artefact to do things with Cisco routers and patch thats mostly a beatific thing, you meliorate undergo the ins and outs of every options when it comes to effort period and employed on creation networks. Working with Frame Relay subinterfaces and separate scope is meet digit much situation.
One think for the ingest of subinterfaces is to circumvent the conception of separate horizon. You request from your CCNA studies that separate scope dictates that a line cannot be advertised discover the aforementioned programme upon which it was scholarly in the prototypal place. In the mass example, R1 is the hub and R2 and R3 are the spokes. All threesome routers are using their fleshly interfaces for inclose passage connectivity, and they are also streaming RIPv2 172.12.123.0 /24. Each router is also business a loopback interface, using the router sort for apiece octet.
R1(config)#int s0
R1(config-if)#ip come 172.12.123.1 255.255.255.0
R1(config-if)#no inclose inverse
R1(config-if)#frame transpose ip 172.12.123.2 122 broadcast
R1(config-if)#frame transpose ip 172.12.123.3 123 broadcast
R1(config-if)#no shut
R2(config)#int s0
R2(config-if)#encap frame
R2(config-if)#no inclose inver
R2(config-if)#frame transpose ip 172.12.123.1 221 broadcast
R2(config-if)#frame transpose ip 172.12.123.3 221 broadcast
R2(config-if)#ip come 172.12.123.2 255.255.255.0
R3(config)#int s0
R3(config-if)#encap frame
R3(config-if)#no inclose inver
R3(config-if)#frame transpose ip 172.12.123.1 321 broadcast
R3(config-if)#frame transpose ip 172.12.123.2 321 broadcast
R3(config-if)#ip come 172.12.123.3 255.255.255.0
R1#show ip line rip
2.0.0.0/32 is subnetted, 1 subnets
R 2.2.2.2 [120/1 via 172.12.123.2, 00:00:20, Serial0
3.0.0.0/32 is subnetted, 1 subnets
R 3.3.3.3 [120/1 via 172.12.123.3, 00:00:22, Serial0
R2#show ip line rip
1.0.0.0/32 is subnetted, 1 subnets
R 1.1.1.1 [120/1 via 172.12.123.1, 00:00:06, Serial0
R3#show ip line rip
1.0.0.0/32 is subnetted, 1 subnets
R 1.1.1.1 [120/1 via 172.12.123.1, 00:00:04, Serial0
The hub router R1 has a line to both loopbacks, but neither crosspiece has a line to the another spoke's loopback. That's because separate scope prevents R1 from business a meshwork via Serial0 if the line was scholarly on Serial0 to begin with.
We've got digit options here, digit of which is to alter spilt scope on the interface. While doing so module hit the desirable gist in our lowercase network, unhealthful separate scope is not a beatific intent and should be avoided whenever possible. Were not feat to do it in this lab, but here is the structure to do so:
R1(config)#interface serial0
R1(config-if)#no ip split-horizon
A meliorate resolution is to configure subinterfaces on R1. The IP addressing module hit to be revisited, but that's no difficulty here. R1 and R2 module ingest 172.12.123.0 /24 to communicate, patch R1 and R3 module ingest 172.12.13.0 /24. R3's serial0 programme module requirement to be renumbered, so let's countenance at every threesome router configurations:
R1(config)#interface serial0
R1(config-if)#encap frame
R1(config-if)#no inclose inverse-arp
R1(config-if)#no ip address
R1(config-if)#interface serial0.12 multipoint
R1(config-subif)#ip come 172.12.123.1 255.255.255.0
R1(config-subif)#frame transpose ip 172.12.123.2 122 broadcast
R1(config-subif)#interface serial0.31 point-to-point
R1(config-subif)#ip come 172.12.13.1 255.255.255.0
R1(config-subif)#frame interface-dlci 123
R2(config)#int s0
R2(config-if)#ip come 172.12.123.2 255.255.255.0
R2(config-if)#encap frame
R2(config-if)#frame transpose ip 172.12.13.3 221 broadcast
R2(config-if)#frame transpose ip 172.12.123.1 221 broadcast
R3(config)#int s0
R3(config-if)#ip come 172.12.13.3 255.255.255.0
R3(config-if)#encap frame
R3(config-if)#frame transpose ip 172.12.13.1 321 broadcast
R3(config-if)#frame transpose ip 172.12.123.2 321 broadcast
A inclose transpose evidence ever obloquy the REMOTE IP come and the LOCAL DLCI. Don't block the programme option!
Show inclose transpose shows us that every the noise mappings on R1 are up and running. Note the static output, which indicates these mappings are a termination of using the inclose transpose command. Pings are not shown, but every threesome routers crapper sound apiece another at this point.
R1#show inclose map
Serial0 (up): ip 172.12.123.2 dlci 122(0x7A,0x1CA0), static,
broadcast, CISCO, position defined, active
Serial0 (up): ip 172.12.13.3 dlci 123(0x7B,0x1CB0), static,
broadcast, CISCO, position defined, active
After the 172.12.13.0 /24 meshwork is additional to R1 and R3s RIP configuration, R2 and R3 today hit apiece other's loopback meshwork in their RIP routing tables.
R2#show ip line rip
1.0.0.0/32 is subnetted, 1 subnets
R 1.1.1.1 [120/1 via 172.12.123.1, 00:00:20, Serial0
3.0.0.0/32 is subnetted, 1 subnets
R 3.3.3.3 [120/1 via 172.12.123.1, 00:00:22, Serial0
R3#show ip line rip
1.0.0.0/32 is subnetted, 1 subnets
R 1.1.1.1 [120/1 via 172.12.13.1, 00:00:20, Serial0
2.0.0.0/32 is subnetted, 1 subnets
R 2.2.2.2 [120/1 via 172.12.13.1, 00:00:22, Serial0
While motion separate scope soured is digit artefact to attain amount IP connectivity, doing so crapper hit another inadvertent results. The ingest of subinterfaces is a more trenchant artefact of allowing the spokes to wager the hub's loopback network.
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