hub and spoke with 2 hubs?

[Andrew White]

Hello,

I've configured a few small hub and soke networks before where you only have 1 hub and 3-4 spokes, but today I saw a hub and spoke diagram that had 2 hubs!  I'm not seen this before and have wondered how on earth you would configure the hubs and spokes?

I can't see how you would configure a spoke to have DLCIs to each hub and spoke without it saying address already mapped.  For example I just did a test in my lab:

Spoke router

interface Serial0/1

ip address 172.12.123.1 255.255.255.0

encapsulation frame-relay

frame-relay map ip 172.12.123.100 121 broadcast  (to get to hub 1)

frame-relay map ip 172.12.123.2 121 broadcast (to get to spoke 2 via hub 1)

frame-relay map ip 172.12.123.3 122 broadcast (to get to spoke 3 via hub 2)

frame-relay map ip 172.12.123.200 122 broadcast (to get to hub 2)

Can't add these as it says they are already there?

frame-relay map ip 172.12.123.2 122 broadcast (to get to spoke 2 via hub 2)

Spoke1(config-if)#frame-relay map ip 172.12.123.2 122

%Address already in map

Spoke1(config-if)#frame-relay map ip 172.12.123.3 121 broadcast

%Address already in map

I'm sure I will have to configure something like this or come across it to fix, any help woudl be most appreciated.

Thanks

[paul driver]

Hello

The reason why its failing is because yoy are using a dlci which is already in use - Map to a dlci not in use and it will work

Res
Paul

Sent from Cisco Technical Support Android App

[Richard Burts]

I would also suggest that part of the difficulty is due to using frame relay multipoint connections where both hubs and all spokes are in a common subnet. That may work for a small network but it does not scale well. It would be much better to have each hub to spoke be configured as a point to point subinterface with its own (/30) subnet. Then the spoke only needs to know how to get to each hub and the hubs keep track of all the other spokes.

HTH

Rick

[Andrew White]

I'm not sure this is possible the more I try, it seems to complain about the IP addresses already in-use and not the DLCIs, maybe as Richard mentions the only way maybe using point-to-pont links?

I have managed to configure the L2 topology between the Hub 1 and the 3 spokes and all can be pinged.  I have now started to configure Spoke 1 to go via Hub 2 to get to Spoke 2 and it complains again:

interface Serial0/1

ip address 172.12.123.1 255.255.255.0

encapsulation frame-relay

clock rate 2000000

frame-relay map ip 172.12.123.100 121 broadcast (to hub 1)

frame-relay map ip 172.12.123.2 121 broadcast (to spoke 2 via hub 1)

frame-relay map ip 172.12.123.200 102 broadcast (to hub 2)

no frame-relay inverse-arp

Spoke1(config-if)#frame-relay map ip 172.12.123.2 102 br (to spoke 2 vi a hub 2)

%Address already in map

Even if I try a different DLCI:

Spoke1(config-if)#frame-relay map ip 172.12.123.2 999 br

%Address already in map

He is the diag in GNS3 I have been using, as I mention Hub 1 to all spokes works and I have just started on Hub2.  Please shed some light, if it's not possible I will just start on a p2p lab instead.  All good fun though:

Thanks