Could be VLAN like one has L2 VPN in the cable specifications. But L2 VPN will limit one to 1024 max per cable line card on a CMTS – it’s a very limited for services arch in cable and I don’t think deployed very widely. The point is a cable modem receiver chip is built to send its upstream data only to the CMTS and likewise receive data from the CMTS – so how can two modems even talk to each other?
The link-local domain on the CMTS is also a well-defined and tied to a virtual L3 network interface that aggregates several physical cable network interfaces and all the modems. As of Fall 2007, CableLabs in the U.S. that certifies CMTS and CM equipment has certified more than one CMTS vendor for Docsis 3.0 IPv6 with ND Proxy support on the CMTS. I will be in Hiroshima, so if anyone would like to understand the cable and CMTS link-local model and mcast for ND in cable, please find me – I am hanging out in 6man, v6ops, INT area and the like. Regards, Hemant From: Dunn, Jeffrey H. [mailto:[email protected]] Sent: Thursday, November 05, 2009 6:35 PM To: Hemant Singh (shemant); Fred Baker (fred); Erik Nordmark; Hesham Soliman; JINMEI Tatuya / 神明達哉; Thomas Narten; Susan Thomson (sethomso); [email protected] Cc: [email protected]; IETF IPv6 Mailing List; [email protected]; Robin Mersh; [email protected]; IPv6 Operations; SAVI Mailing List; Dunn, Jeffrey H. Subject: RE: Broadband Forum liaison to IETF on IPv6 security Colleagues, I may be missing something, but it appears that, in the cases described, the two hosts downstream of two separate cable modems are off link to each other. This brings up the question: Do there two cable modems constitute two virtual interfaces, like two VLANs on the same physical router interface? If so, this is an architectural, rather than an implementation, question. Thoughts? Best Regards, Jeffrey Dunn Info Systems Eng., Lead MITRE Corporation. (301) 448-6965 (mobile)
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