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cdp over a frf8 connection


i have a 7206 router which is connected to a providers atm network.

there is a branch on the other side which has a connection to the central 7206 over a frf8 connection.

this means this router is connected to a fr network and the provider does the fr_to_atm conversation.

it is workil´ng well, but we have no cdp-information about the 7206 at the it

branche end.

it seems that the cdp paket which the 7206 sends out never comes to the branch router.


interface ATM3/0

description MPLSRBGOPE02: phy.Link to MPLSRBGOLS02 (ATM3/0)

no ip address

logging event subif-link-status

load-interval 30

no atm ilmi-keepalive

cdp enable



interface ATM3/0.150 point-to-point

description MPLSRBGOPE02: ***** Verbdg. zu r-mauthau1 (ATM3/0.150) *****

bandwidth 512

ip address

ip mtu 1500

cdp enable

pvc 1/50

vbr-nrt 1536 574 200

encapsulation aal5snap

max-reserved-bandwidth 95

service-policy output queue_trunc


Konfig from the branch router:

interface Serial0/0

description r-mauthau1: phy. FrameRelay-Interface (Se0/0)

bandwidth 1920

no ip address

max-reserved-bandwidth 95

encapsulation frame-relay IETF

load-interval 30

no fair-queue

cdp enable

frame-relay traffic-shaping

frame-relay lmi-type q933a


interface Serial0/0.1 point-to-point

description r-mauthau1: Verbg. zu MPLSRBGOPE02 (Se0/0.1)

bandwidth 512

ip address

frame-relay class 512k

frame-relay interface-dlci 16


any idea ??????????


Re: cdp over a frf8 connection


When using FRF8 in translational mode, the payload information carried in the RFC1490 FR packets has to be translated into RFC1483 ATM packets. This means that the provider switches have to have knowledge of CDP for this to happen. In general, they will not have knowledge of CDP and will not be able to translate the packets. That is why you do not see the CDP information across FRF8 interfaces.

One option you have, if your provider supports it, is to use FRF.8 in transparent mode, in which case you do not need the provider to translate between FR and ATM payloads. But I'm not sure you would want to do all that for CDP information...

Hope that helps - pls rate the post if it does.