1210
C
HAPTER
72: IP
V
6 M
ULTICAST
R
OUTING
AND
F
ORWARDING
C
ONFIGURATION
Implementation of the RPF mechanism
Upon receiving an IPv6 multicast packet sent from a multicast source S to an IPv6
multicast group G, the router first searches its IPv6 multicast forwarding table:
1
If the corresponding (S, G) entry exists, and the interface on which the packet
actually arrived is the incoming interface in the IPv6 multicast forwarding table,
the router forwards the packet to all the outgoing interfaces.
2
If the corresponding (S, G) entry exists, but the interface on which the packet
actually arrived is not the incoming interface in the IPv6 multicast forwarding
table, the packet is subject to an RPF check.
■
If the result of the RPF check shows that the RPF interface is the incoming
interface of the existing (S, G) entry, this means that the (S, G) entry is correct
but the packet arrived from a wrong path and is to be discarded.
■
If the result of the RPF check shows that the RPF interface is not the incoming
interface of the existing (S, G) entry, this means that the (S, G) entry is no
longer valid. The router replaces the incoming interface of the (S, G) entry with
the interface on which the packet actually arrived and forwards the packet to
all the outgoing interfaces.
3
If no corresponding (S, G) entry exists in the multicast forwarding table, the packet
is also subject to an RPF check. The router creates an (S, G) entry based on the
relevant routing information and using the RPF interface as the incoming interface,
and installs the entry into the IPv6 multicast forwarding table.
■
If the interface on which the packet actually arrived is the RPF interface, the RPF
check is successful and the router forwards the packet to all the outgoing
interfaces.
■
If the interface on which the packet actually arrived is not the RPF interface, the
RPF check fails and the router discards the packet.
RPF Check
The basis for an RPF check is an IPv6 unicast route. The IPv6 unicast routing table
contains the shortest path to each destination subnet. A multicast routing protocol
does not independently maintain any type of unicast routes; instead, it relies on
the existing unicast routing information in creating multicast routing entries.
■
When performing an RPF check, the router searches its IPv6 unicast routing
table using the IP address of the “packet source” as the destination address
and automatically selects the optimal route as the RPF route. The outgoing
interface in the corresponding routing entry is the RPF interface and the next
hop is the RPF neighbor. The router considers the path along which the IPv6
multicast packet from the RPF neighbor arrived on the RPF interface to be the
shortest path that leads back to the source.
n
The above-mentioned “packet source” can mean different things in different
situations
■
For a packet traveling along the shortest path tree (SPT) from the multicast
source to the receivers or the source-based tree from the multicast source to
the rendezvous point (RP), “packet source” means the multicast source.
■
For a packet traveling along the rendezvous point tree (RPT) from the RP to the
receivers, “packet source” means the RP.
Summary of Contents for MSR 50 Series
Page 152: ...152 CHAPTER 5 ATM CONFIGURATION...
Page 210: ...210 CHAPTER 6 DCC CONFIGURATION...
Page 234: ...234 CHAPTER 7 DLSW CONFIGURATION...
Page 344: ...344 CHAPTER 14 X 25 AND LAPB CONFIGURATION...
Page 350: ...350 CHAPTER 15 LINK AGGREGATION OVERVIEW...
Page 358: ...358 CHAPTER 17 MODEM CONFIGURATION...
Page 486: ...486 CHAPTER 23 MSTP CONFIGURATION...
Page 506: ...506 CHAPTER 25 VOICE VLAN CONFIGURATION...
Page 510: ...510 CHAPTER 26 PORT ISOLATION CONFIGURATION...
Page 524: ...524 CHAPTER 27 DYNAMIC ROUTE BACKUP CONFIGURATION...
Page 538: ...538 CHAPTER 28 LOGICAL INTERFACE CONFIGURATION...
Page 548: ...548 CHAPTER 29 CPOS INTERFACE CONFIGURATION...
Page 572: ...572 CHAPTER 32 DHCP OVERVIEW...
Page 604: ...604 CHAPTER 36 DHCP SNOOPING CONFIGURATION...
Page 608: ...608 CHAPTER 37 BOOTP CLIENT CONFIGURATION...
Page 646: ...646 CHAPTER 42 IP UNICAST POLICY ROUTING CONFIGURATION...
Page 650: ...650 CHAPTER 43 UDP HELPER CONFIGURATION...
Page 738: ...738 CHAPTER 50 IPV6 UNICAST POLICY ROUTING CONFIGURATION...
Page 770: ...770 CHAPTER 51 TERMINAL ACCESS CONFIGURATION...
Page 798: ...798 CHAPTER 52 FEP INSTALLATION AND CONFIGURATION...
Page 808: ...808 CHAPTER 53 TERMINAL ACCESS TROUBLESHOOTING...
Page 814: ...814 CHAPTER 54 TERMINAL ACCESS FAQ...
Page 824: ...824 CHAPTER 55 IP ROUTING OVERVIEW...
Page 876: ...876 CHAPTER 56 BGP CONFIGURATION...
Page 916: ...916 CHAPTER 57 IS IS CONFIGURATION...
Page 970: ...970 CHAPTER 58 OSPF CONFIGURATION...
Page 1006: ...1006 CHAPTER 60 ROUTING POLICY CONFIGURATION...
Page 1013: ...Configuration Example 1013 3 1 ms 1 ms 1 ms 1 1 2 2 Trace complete...
Page 1014: ...1014 CHAPTER 61 STATIC ROUTING CONFIGURATION...
Page 1048: ...1048 CHAPTER 63 IPV6 IS IS CONFIGURATION...
Page 1068: ...1068 CHAPTER 64 IPV6 OSPFV3 CONFIGURATION...
Page 1080: ...1080 CHAPTER 65 IPV6 RIPNG CONFIGURATION...
Page 1114: ...1114 CHAPTER 68 MULTICAST ROUTING AND FORWARDING CONFIGURATION...
Page 1160: ...1160 CHAPTER 70 MSDP CONFIGURATION...
Page 1234: ...1234 CHAPTER 73 MLD CONFIGURATION...
Page 1278: ...1278 CHAPTER 74 IPV6 PIM CONFIGURATION...
Page 1310: ...1310 CHAPTER 75 MULTICAST VPN CONFIGURATION...
Page 1344: ...1344 CHAPTER 76 MPLS BASICS CONFIGURATION...
Page 1458: ...1458 CHAPTER 78 MPLS L2VPN CONFIGURATION...
Page 1556: ...1556 CHAPTER 79 MPLS L3VPN CONFIGURATION...
Page 1588: ...1588 CHAPTER 80 DVPN CONFIGURATION...
Page 1648: ...1648 CHAPTER 85 QOS POLICY CONFIGURATION...
Page 1696: ...1696 CHAPTER 89 MPLS QOS CONFIGURATION...
Page 1708: ...1708 CHAPTER 90 DAR CONFIGURATION...
Page 1728: ...1728 CHAPTER 91 FRAME RELAY QOS CONFIGURATION...
Page 1750: ...1750 CHAPTER 92 802 1X CONFIGURATION...
Page 1788: ...1788 CHAPTER 93 AAA RADIUS HWTACACS CONFIGURATION...
Page 1810: ...1810 CHAPTER 95 MAC AUTHENTICATION CONFIGURATION...
Page 1850: ...1850 CHAPTER 97 PKI CONFIGURATION...
Page 1872: ...1872 CHAPTER 98 PORTAL CONFIGURATION...
Page 1970: ...1970 CHAPTER 106 BACKUP CENTER CONFIGURATION...
Page 2048: ...2048 CHAPTER 110 NETSTREAM CONFIGURATION...
Page 2084: ...2084 CHAPTER 112 RMON CONFIGURATION...
Page 2094: ...2094 CHAPTER 113 SNMP CONFIGURATION...
Page 2114: ...2114 CHAPTER 115 FTP CONFIGURATION...
Page 2124: ...2124 CHAPTER 117 SYSTEM MAINTAINING AND DEBUGGING...
Page 2154: ...2154 CHAPTER 119 INFORMATION CENTER CONFIGURATION...
Page 2170: ...2170 CHAPTER 121 MAC ADDRESS TABLE MANAGEMENT CONFIGURATION...
Page 2186: ...2186 CHAPTER 123 POE CONFIGURATION...
Page 2198: ...2198 CHAPTER 125 ACFP CONFIGURATION...
Page 2206: ...2206 CHAPTER 126 ACSEI CONFIGURATION...
Page 2216: ...2216 CHAPTER 127 TRACK CONFIGURATION...
Page 2232: ...2232 CHAPTER 128 IPX CONFIGURATION...
Page 2242: ...2242 CHAPTER 129 VOICE OVERVIEW...
Page 2244: ...2244 CHAPTER 130 VOIP OVERVIEW...
Page 2288: ...2288 CHAPTER 132 VOICE ENTITY CONFIGURATION...
Page 2342: ...2342 CHAPTER 134 E1 AND T1 CONFIGURATION...
Page 2354: ...2354 CHAPTER 135 FAX OVER IP CONFIGURATION...
Page 2366: ...2366 CHAPTER 136 H 323 CONFIGURATION...
Page 2384: ...2384 CHAPTER 137 SIP OVERVIEW...