Chapter 23: IPv6
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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When a node is looking for a neighbor on the link with a given IPv6 unicast address and it does not have an active neighbor
cache entry containing a unicast MAC address for that unicast IPv6 address, it will first send an ICMPv6 Neighbor
Solicitation message (similar to an IPv4 ARP Request message) to the associated solicited node multicast address in order
to resolve the unknown unicast MAC address. The assumption is that there is only 1 interface (or a small number of
interfaces) on the link that are using an IPv6 unicast address containing the same low-order 24 bits, and hence, only these
nodes will be listening for their solicited node MAC multicast addresses (unlike IPv4 ARP where all nodes would have heard
the broadcast ARP Request message). Furthermore, only the node that is actually using the full matching target IPv6
unicast address will respond with a ICMPv6 Neighbor Advertisement message, so the requesting node can expect that
there will be only one response or none at all.
This feature supports the well-known IPv6 multicast addresses and their equivalent ethernet MAC addresses in the table
below. Note that packets with link-local scope multicast addresses will be consumed by the control plane and will not be
reflected back to cable interfaces. The C4/c CMTS supports only link-local multicast.
Table 92.
IPv6 Well Known Multicast Groups
Address
Description
ff02::1
All nodes on the local network segment
ff02::2
All routers on the local network segment
ff02::5
OSPFv3 AllSPF routers
ff02::6
OSPFv3 AllDR routers
ff02::9
RIP routers
ff02::a
EIGRP routers
ff02::d
PIM routers
ff02::16
MLDv2 Reports
ff02::1:2
All DHCP servers and relay agents on the local
network
ff05::1:3
All DHCP servers on the local network
ff0x::fb
Multicast DNS