Hi All,
I have problem and have no idea how to solve it.
I have DHCP connected to the CMTS by Ethernet.
CabelModem connected to the CMTS by Coaxial.
Some device with linux connected to CM.
Device, CMTS, DHCP are supporting IPv4 and IPv6.
CM is support only IPv4 but has bridge between networks (Device <--> CMTS).
When I do ping from Device to Cabel interface of CMTS, CMTS doesn't send any Neighbor solicitation to Device (checked with tcpdump) and IP of Device is marked as INCOMPLETE in Neighbor list on CMTS.
When I do ping from Device to DHCP, DHCP sends NS to Device then Device answered with NA (neighbor advert.) and CMTS catches that packet and adds IP of Device as valid/complete in Neighbor list.
CMTS - BSR64000
Any Idea?
Thank you in advance.
What model of cable modem are you using? Be aware that legacy 2.0 cable modems which are not supporting IPv6 let no Multicast-Traffic from CMTS over the CM to the CMCI Interface. Sure you can select a Multicast-MAC-Address to go through the cable modem from CMTS to CPE but the count of this Multicast-MAC-Addresses are limited to 16. But this will not help you for the mass of Multicast-Adresses of the Solicited-Node-Adresses which are build by the MAC-Address of the CPE.
In other direction, from CPE over CM to CMTS the Multicast-Traffic will pass.
The Only way how D2.0 cable modem will work with NDP is, if the CMTS will answer the Neighbour-Solicitation from CPE with a Unicast Neighbour-Advertising, where the Destination-Address will be the Link-Local-Address from the CPE where the NS will come from. But the most CMTSes will just send NDP-Traffic to Multicast-Addresses (Solicited-Node-Address aso.). I have no experiences on Motorola CMTS, but for Arris C4, Cisco 7k, 10k and Casa 3k2 and the Casa-CMTS is the only one who will answer via Unicast-Traffic like to Link-Local-Addresses. I mean in the DOCSIS-Specs (MULPI) is just talking about NDP via Multicast, no Unicast like in the RFC for NDP.