Frame-Relay question regarding Multipoint and PTP

Hi everyone. I'm studying for ICND2 and I have a L2 question I was hoping some of you could help me iron out. I must be missing something fundamental here...

I'm setting up a hub and spoke frame-relay lab at home with four routers - Here's a quick overview:

2520 - is the frame-relay switch. This has been properly configured using Chris Bryant's instructions and has had no issues (I've done frame relay labs in the past on it and it has always worked perfectly.)

3620 - Is the Hub. I have physical interface S1/0 split into two sub-interfaces.
S1/0.1 ip address 9.1.1.1 /30 Multipoint
S1/0.2 ip address 210.1.1.1 /30 Point-to-Point
DLCI 122
DLCI 123

2611 - Is the spoke to 9.1.1.1
Interface S0/1 ip address 9.1.1.2 /30
DLCI 221

2507 - Is the spoke to 210.1.1.1
InterfaceS0 ip address 210.1.1.2 /30
DLCI 321

BOTH PVCs show up as Active on the Hub. Network 9.1.1.0 /30 (the multipoint connection) is perfectly fine but I cannot ping 210.1.1.2 which is the PTP connection. My guess is I'm missing something basic about PTP here. Do I need to tell the spoke router (210.1.1.2) that this is a PTP connection somehow (my best guess)?

All of the ip addresses and frame mappings have been triple checked. Inverse arp off.

Thanks for any guidance !

Find more posts tagged with

Free for TechExams community: Cybersecurity salary guide

Compare cert salaries and plan your next career move

Button

Comments

SMR511

I forgot to mention, when I make the 210.1.1.0 /30 network Multipoint, everything works fine.

That's why I believe my problem is with understanding/configuring PTP.

kryolla

ptp just needs the encap frame command and frame interface dlci ### command and your done, only one dlci can be used in ptp. Multipoint needs the encap frame command and use inverse arp or frame map command. What does your debug frame packets say when you try to ping?

SMR511

Thanks! Here's the config...

On Hub subinterface S1/0.2
ip address 210.1.1.1 255.255.255.252
encap frame
no frame inverse
frame interface-dlci 123

On spoke interface S0
ip address 210.1.1.2 255.255.255.252
encap frame
no frame inverse
frame interface-dlci 321

"debug frame packet" comes back with "Encaps failed--no map entry link 7 (IP)

So it's not setting up a frame map ? Both interfaces are up/up.

SMR511

So actually R3 (spoke) pinging R1 (hub) comes back with:

"Encaps failed--no map entry link 7 (IP)"

But R1 (hub) pinging R3 (spoke) comes back with:

"dlci 123 (0x1CB1), pkt type 0x800 (IP), datagram size 10"
(It's sending CDP packets too, similar result.)

deth1k

leave the inverse arp on the p2p interface, this is why you are getting encapsulation failure.

kryolla

deth1k wrote: »

leave the inverse arp on the p2p interface, this is why you are getting encapsulation failure.

inverse arp is only for multipoint

kryolla

SMR511 wrote: »

Thanks! Here's the config...

On Hub subinterface S1/0.2
ip address 210.1.1.1 255.255.255.252
encap frame
no frame inverse
frame interface-dlci 123

On spoke interface S0
ip address 210.1.1.2 255.255.255.252
encap frame
no frame inverse
frame interface-dlci 321

"debug frame packet" comes back with "Encaps failed--no map entry link 7 (IP)

So it's not setting up a frame map ? Both interfaces are up/up.

on the spoke since it is the main interface which is multipoint you need a frame map for static mapping or do inverse arp

SMR511

Thank you !!!!!