Single Interface to multiple WAN location

[Dinesh Murthy]

Hi,

I had a doubt in configuring single interface to multiple wan locations,

Recently one service is provided single ethernet output in HUB location and other 4 ethernets for the respective branch locations.

I need to configure EIGRP on this link.

Shall I need to create a subinterface on the hub interface ? and enable routing protocol ? 

how the service providers are working in these kinds of tasks.

Kindly provide your valuable suggestion to proceed.

Regards

Dinesh Murthy

[Georg Pauwen]

Hello Dinesh,

it all depends on the equipment used and your requirements. Providers typically set up MPLS hub and spoke Layer 3 VPNs, as described in the link below. If all WAN connections and devices are managed by yourself, subinterfaces on the hub would indeed be the solution. You would enable EIGRP and advertise the networks configured on the subinterfaces.

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/5_x/nx-os/mpls/configuration/guide/mp_vpn_hub_spoke.html

[Dinesh Murthy]

Hi enrico,gpauwen

Thanks a lot for your valuable suggestions.

The service provider is a local vendor, they are providing fiber connectivity between hub to spoke locations, don't know how they are configured, whether it is MPLS or simple layer2 connectivity.

I will get the details from the provider and let you know. if they did not  configure MPLS VPN, shall i configure subinterface and enable routing protocol ? how good is it ?

Core router is 3945.

Regards

Dinesh Murthy

[e.ciollaro]

shall i configure subinterface and enable routing protocol ? how good is it ?

May be yes, may be no ;-)  

I mean that it depends on how the ISP configures the WAN link: it could be a single multiple access network (let me say something like a single VLAN connecting the sites) or it could be a trunk access with 4 VLAN each one dedicated to a point-to-point connection between Hub and branches. In the first case all 5 sites has has WAN interf on the same network; in this case you need just one interf in your Hub site and you can configure an IGP between  sites (check with ISP that it's network it transparent and IGP multicast traffic could traverse the WAN). In the second scenario multiple subinterf could be required. In any case  wait until the ISP emplane you which kind of service is delivering and ask for a template config.

Another 

[Dinesh Murthy]

Hi Enrico,

I checked with the vendor, they are going to configure VLAN only. they asked me to configure all the four locations in a single(same) subnet. I think just they place a switch in betweens the links.

which protocol needs to configure shall I go with EIGRP or OSPF multi-point ?

 Regards

Regards

Dinesh Murthy

[Georg Pauwen]

Dinesh,

who is your ISP (that is, what is the name of the company) ? All locations in the same subnet sounds odd. Have you had any written exchange with your vendor that you can post here ?

[Dinesh Murthy]

Hi.

They are not giving exact details, while I enquired they told that enabled VLAN in their and mapped the ports. They placed a switch in our premises and provided a port to connect the link. I think it's just a layer2 path.

[Georg Pauwen]

Dinesh,

how are they connecting the branches to the hub ? Or is there already a connection between the branches and the hub ? They need to tell you at the very least what they have configured. Who is the provider ?

[Dinesh Murthy]

Enrico

They are small scale service provider call SKYLINK, they provided a fiber cable connectivity to all our branches, and they placed Dlink fiber switch in the locations.

If I ask about config details, they said VLAN in between the locations, I think it is an extended LAN.

[Dinesh Murthy]

Enrico

I have attached a sample topology, needs to advise and suggestions.

If enabled both the protocol EIGRP and OSPF by default router will choose EIGRP because of the metrics. But OSPF link is 100Mbps and EIGRP link is 4Mbps only, because of the metric it will choose EIGRP. How to overcome with OSPF ?

Already working with EIGRP only, shall I go ahead and OSPF in this link ?

If it is, is there any possibility to achieve load balancing with different protocols ?

Existing network alone with EIGRP only..

[e.ciollaro]

Hi Murthy

I'm a little bit confused about the sample config because OSPF Area 0 cover just the switch; I guess OSPF area  comprise R2, R3 and R4-Sw1 interf (but not the R4-R1 interf). If so and if you can't use EIGRP for this part of the network (by the way, why i can't use EIGRP for the whole network)  you can change the OSPF admin distance using:

distance ospf inter-area 80

I didn't test in lab but I think it works properly .

If it is, is there any possibility to achieve load balancing with different protocols ?

Not sure, may be having the same admin distance and the same metric but IGPs have different way to measure the metric so it's hard to have exactly the same metric; I suggest not to do or at least, not in a production network.

Finally, be careful with redistribution to avoid routing loop and/or routing feedback: I suggest to redistribute just on R1:

• redistribute OSPF in EIGRP
• redistribute just the default network in OSPF

This way R2 and R3 can't use R4 has a backup in case of a failure of the R1-Sw1 link but probably this is good due to the low bandwidth of the link.

If you configure redistribution also on R4 be careful because you have two redistribution point so routing feedback e routing loop may occur.

Bye

enrico

PS: please rate if useful

[Dinesh Murthy]

Hi Enrico,

Thanks a lot for your inputs, As you mentioned earlier in the earlier post I will go with EIGRP in the production network.

I will work this topology in the lab setup.

Regards

Dinesh Murthy

[e.ciollaro]

Hi,

if hey really provided a layer2 between sites you can configure both EIGRP or OSPF, the right protocol depends on your needs/requirement. EIGRP is easy to deploy, if you has just a few network and you has more experience with EIGP then OSPF, EIGRP could be a good choice.

enrico

PS: please rate if useful

[e.ciollaro]

Hi

the main question is "which service is providing the ISP ?" Is it an MPLS network ? If so, in my experience, there is no need to use multiple subinterf:  usually there is a single point-to-point link between the CE (router in your site) and PE (ISP router). Over this link you can configure static routing (if you have no backup link it is the easy way) or BGP (IGP is less common). I work in an ISP but we never use EIGRP or OSPF as PE-CE routing protocol. In any case the best thing to do is asking the ISP which is the required/allowed config on WAN link

Bye,

enrico

PS: please rate if useful