Eigrp over FR, and multipoint

[hanwucisco]

Eigrp over FR, Is it possible to created a link of which, one side is multipoint sub-interface, and the other end is point-to-point? For instance, in this diagram, can I set to sub-intefaces at R1 into multipoint, and the ones at spoke routers into point-to-point, so that they are in the some subnet? Or you have to make all of them into a multipoint?

thanks,

[Thotsaphon Lueangwattanaphong]

Hi,

  You can do it. Keep in mind, spoke routers will only receive routes from hub router because of this design. You need to disable "split-horizon" on Hub router.

  Note: When you disable "split-horizon" on hub router, spoke router can connect each other because the next-hop pointing to Hub. So you don't need the FR circuit between spokes.

Toshi

[hanwucisco]

I did. I can, from one spoke, see the routes to the other spoke. However, I can't ping it. Here are the configs,

thanks,

======Hub config=============
interface Loopback0
ip address 10.1.1.1 255.255.255.0
!
interface Loopback1
ip address 172.16.101.1 255.255.255.0
!
interface Serial0/0
ip address 10.1.0.1 255.255.255.0
encapsulation frame-relay
no ip split-horizon eigrp 1
serial restart-delay 0
frame-relay map ip 10.1.0.2 102 broadcast
frame-relay map ip 10.1.0.3 103 broadcast
!
!
router eigrp 1
network 0.0.0.0
no auto-summary
===========Spoke 1=================

interface Loopback0
ip address 10.1.2.2 255.255.255.0
!
interface Loopback1
ip address 172.16.102.1 255.255.255.0
!
interface Serial0/0
ip address 10.1.0.2 255.255.255.0
encapsulation frame-relay
serial restart-delay 0
frame-relay interface-dlci 201

!
router eigrp 1
network 0.0.0.0
no auto-summary
==============Spoke 2================
interface Loopback0
ip address 10.1.3.3 255.255.255.0
!
interface Loopback1
ip address 172.16.103.1 255.255.255.0
!
interface Loopback91
no ip address
!
interface Serial0/0
ip address 10.1.0.3 255.255.255.0
encapsulation frame-relay
serial restart-delay 0
frame-relay interface-dlci 301

!
router eigrp 1
network 0.0.0.0
no auto-summary

[cadet alain · Accepted solution]

Hi,

You are using physical interfaces on your spokes so either you use inverseARP which is your case or you configure static mappings with the frame map command.To get communication from spoke to spoke you need these mappings and not the frame-relay interface-dlci command you issued which is for a point-to-point subinterface.

To verify, just do a debug frame packet while pinging your other spoke network and you'll see the encapsulation failed string.

Regards.

Alain.

[Thotsaphon Lueangwattanaphong · Accepted solution]

Hi,

   It won't work when you ping from its serail interface on the spoke router. It has no mapping on the other spokes because frame-relay inverse-arp and no circuit between them. Your configuration should be modified as follows:

===========Spoke 1=================

!

interface Serial0/0

no ip address

encapsulation frame-relay

!

interface Serial0/0.1  point-to-point

ip address 10.1.0.2 255.255.255.0
frame-relay interface-dlci 201

!

==============Spoke 2================

!

interface Serial0/0

no ip address

encapsulation frame-relay

!

interface Serial0/0.1  point-to-point
ip address 10.1.0.3 255.255.255.0
frame-relay interface-dlci 301

!

    Note: You can manually do frame-relay maps on the spoke routers as well but it's not a good idea to do so. Let's say 50 spokes in your environment.

HTH,

Toshi

[cadet alain]

Hi Toshi,

AFAIK the frame map is not supported on p2p subinterfaces. I suggested frame maps because the spokes were using physical interfaces.

But I don't see the difference between 50 frame maps and 50 frame interface-dlci command

And I don't think this will work as p2p must be in different networks which is not the case here so I think you must use a different subnet for each spoke and 2 multipoint subinterfaces on the hub where you'll be using frame maps or frame interface-dlci( if you want to use inverse arp).

Regards.

Alain.

[Thotsaphon Lueangwattanaphong]

Alain,

     I know what you mentioned. In his case, you're gonna do frame-relay mapping for other spokes because there are no circuit between them. If you want to test connection between spoke routers by using a source ip address of serial interface.

===========Spoke 1=================
interface Serial0/0
frame-relay map ip 10.1.0.1 201 broadcast

frame-relay map ip 10.1.0.3 201

!

===========Spoke 2=================
interface Serial0/0
frame-relay map ip 10.1.0.1 301 broadcast

frame-relay map ip 10.1.0.2 301

!

    Hope I pointed something out. And yes in real world we would do point-to-point sub-interfaces(different subnets) for hub and spoke to avoid unusal things.  I give you 5 for talking this in this thread.

Toshi