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Graft, Assert, Assert mechanism

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The flood-and-prune process takes place periodically. A pruned state timeout mechanism is provided. A pruned branch restarts multicast forwarding when the pruned state times out and then is pruned again when it no longer has any multicast receiver. NOTE: Pruning has a similar implementation in PIM-SM. Graft Assert When a host attached to a pruned node joins a multicast group, to reduce the join latency, PIM-DM uses a graft mechanism to resume data forwarding to that branch. The process is as follows: 1. The node that needs to receive multicast data sends a graft message toward its upstream node as a request to join the SPT again. 2. After receiving this graft message, the upstream node puts the interface on which the graft was received into the forwarding state and responds with a graft-ack message to the graft sender. 3. If the node that sent a graft message does not receive a graft-ack message from its upstream node, it will keep sending graft messages at a configurable interval until it receives an acknowledgment from its upstream node. Where more than one multicast router exists, the assert mechanism shuts off duplicate multicast flows onto the same multi-access network. It does this by electing a unique multicast forwarder on the multi-access network. Figure 37 Assert mechanism As shown in Figure 37, after Router A and Router B receive an (S, G) packet from the upstream node, they both forward the packet to the local subnet. As a result, the downstream node Router C receives two identical multicast packets, and both Router A and Router B, on their own downstream interface, receive a duplicate packet forwarded by the other. After detecting this condition, both routers send an assert message to all PIM routers (224.0.0.13) on the local subnet through the downstream interface on which the packet was received. The assert message contains the multicast source address (S), the multicast group address (G), and the preference and metric of the unicast route/MBGP route/multicast static route to the source. By comparing these parameters, either Router A or Router B becomes the unique forwarder of the subsequent (S, G) packets on the multi-access subnet. The comparison process is as follows: 1. The router with a higher preference to the source wins; 2. If both routers have the same preference to the source, the router with a smaller metric to the source wins; 104

Section	Page
Title Page	1
IP Multicast Configuration Guide	3
Multicast overview	12
Introduction to multicast	12
Information transmission techniques	12
Unicast	12
Broadcast	13
Multicast	13
Multicast features	14
Common notations in multicast	15
Multicast advantages and applications	15
Multicast advantages	15
Multicast applications	15
Multicast models	16
ASM model	16
SFM model	16
SSM model	16
Multicast architecture	16
Multicast addresses	17
IP multicast addresses	17
Ethernet multicast MAC addresses	19
Multicast protocols	20
Layer 3 multicast protocols	20
Layer 2 multicast protocols	21
Multicast packet forwarding mechanism	22
Configuring IGMP snooping	23
Overview	23
Basic concepts in IGMP snooping	23
IGMP snooping related ports	23
Aging timers for dynamic ports in IGMP snooping and related messages and actions	24
How IGMP snooping works	25
When receiving a general query	25
When receiving a membership report	25
When receiving a leave message	26
IGMP snooping proxying	26
Protocols and standards	28
IGMP snooping configuration task list	28
Configuring basic IGMP snooping functions	29
Enabling IGMP snooping	29
Specifying the version of IGMP snooping	29
Configuring static multicast MAC address entries	30
Configuration guidelines	30
Configuration procedure	30
Configuring IGMP snooping port functions	30
Setting aging timers for dynamic ports	31
Configuring aging timers for dynamic ports globally	31
Configuring aging timers for dynamic ports in a VLAN	31
Configuring static ports	31
Configuration guidelines	32
Configuration procedure	32
Configuring a port as a simulated member host	32
Enabling IGMP snooping fast-leave processing	33
Enabling IGMP snooping fast-leave processing globally	33
Enabling IGMP snooping fast-leave processing on a port	33
Disabling a port from becoming a dynamic router port	33
Configuring IGMP snooping querier	34
Enabling IGMP snooping querier	34
Configuring parameters for IGMP queries and responses	35
Configuring the global parameters for IGMP queries and responses	35
Configuring the parameters for IGMP queries and responses in a VLAN	35
Configuring the source IP addresses for IGMP queries	36
Configuring IGMP snooping proxying	36
Enabling IGMP snooping proxying	36
Configuring a source IP address for the IGMP messages sent by the proxy	37
Configuring an IGMP snooping policy	37
Configuring a multicast group filter	37
Configuration guidelines	38
Configuration procedure	38
Configuring multicast source port filtering	38
Configuring multicast source port filtering globally	38
Configuring multicast source port filtering on a port	39
Enabling dropping unknown multicast data	39
Configuration guidelines	39
Configuration procedure	39
Configuring IGMP report suppression	40
Setting the maximum number of multicast groups that a port can join	40
Enabling multicast group replacement	41
Enabling multicast group replacement globally	41
Enabling multicast group replacement on a port	41
Setting the 802.1p precedence for IGMP messages	41
Setting the 802.1p precedence for IGMP messages globally	42
Setting the 802.1p precedence for IGMP messages in a VLAN	42
Enabling the IGMP snooping host tracking function	42
Enabling the IGMP snooping host tracking function globally	42
Enabling the IGMP snooping host tracking function in a VLAN	42
Setting the DSCP value for IGMP messages	42
Displaying and maintaining IGMP snooping	43
IGMP snooping configuration examples	44
Group policy and simulated joining configuration example	44
Network requirements	44
Configuration procedure	44
Verifying the configuration	45
Static port configuration example	46
Network requirements	46
Configuration procedure	47
Verifying the configuration	48
IGMP snooping querier configuration example	49
Network requirements	49
Configuration procedure	50
Verifying the configuration	51
IGMP snooping proxying configuration example	51
Network requirements	51
Configuration procedure	52
Verifying the configuration	53
Troubleshooting IGMP snooping	54
Layer 2 multicast forwarding cannot function	54
Symptom	54
Analysis	54
Solution	54
Configured multicast group policy fails to take effect	54
Symptom	54
Analysis	54
Solution	55
Appendix	55
Processing of multicast protocol messages	55
Configuring multicast VLANs	56
Overview	56
Sub-VLAN-based multicast VLAN	56
Port-based multicast VLAN	57
Multicast VLAN configuration task list	58
Configuring a sub-VLAN-based multicast VLAN	58
Configuration guidelines	58
Configuration procedure	58
Configuring a port-based multicast VLAN	59
Configuration prerequisites	59
Configuring user port attributes	59
Configuring multicast VLAN ports	60
Configuration guidelines	60
Configuration procedure	60
Displaying and maintaining multicast VLAN	60
Multicast VLAN configuration examples	61
Sub-VLAN-based multicast VLAN configuration example	61
Network requirements	61
Configuration procedure	61
Verifying the configuration	63
Port-based multicast VLAN configuration example	65
Network requirements	65
Configuration procedure	65
Verifying the configuration	66
Configuring multicast routing and forwarding	68
Overview	68
RPF check mechanism	68
RPF check process	68
RPF check implementation in multicast	69
Static multicast routes	70
Changing an RPF route	70
Creating an RPF route	71
Multicast forwarding across unicast subnets	72
Multicast traceroute	72
Concepts in multicast traceroute	72
Introduction to multicast traceroute packets	73
Process of multicast traceroute	73
Configuration task list	73
Enabling IP multicast routing	73
Configuring multicast routing and forwarding	74
Configuring static multicast routes	74
Configuring a multicast routing policy	74
Configuring a multicast forwarding range	75
Configuring the multicast forwarding table size	75
Tracing a multicast path	76
Displaying and maintaining multicast routing and forwarding	76
Configuration examples	77
Changing an RPF route	77
Network requirements	77
Configuration procedure	78
Verifying the configuration	79
Creating an RPF route	79
Network requirements	79
Configuration procedure	80
Verifying the configuration	81
Multicast forwarding over a tunnel	81
Network requirements	81
Configuration procedure	82
Verifying the configuration	84
Troubleshooting multicast routing and forwarding	85
Static multicast route failure	85
Symptom	85
Analysis	85
Solution	85
Multicast data fails to reach receivers	85
Symptom	85
Analysis	85
Solution	85
Configuring IGMP	87
Overview	87
IGMP versions	87
Introduction to IGMPv1	87
Enhancements in IGMPv2	89
Querier election mechanism	89
\	89
Enhancements in IGMPv3	89
Enhancements in control capability of hosts	89
Enhancements in query and report capabilities	90
IGMP SSM mapping	91
IGMP proxying	92
Protocols and standards	93
IGMP configuration task list	93
Configuring basic IGMP functions	94
Enabling IGMP	94
Configuring IGMP versions	94
Configuring an IGMP version globally	94
Configuring an IGMP version on an interface	95
Configuring static joining	95
Configuration guidelines	95
Configuration procedure	95
Configuring a multicast group filter	95
Setting the maximum number of multicast groups that an interface can join	96
Adjusting IGMP performance	96
Configuration prerequisites	96
Configuring Router-Alert option handling methods	97
Configuring Router-Alert option handling methods globally	97
Configuring Router-Alert option handling methods on an interface	97
Configuring IGMP query and response parameters	98
Configuration guidelines	98
Configuration procedure	98
Configuring IGMP fast-leave processing	100
Enabling the IGMP host tracking function	100
Enabling the IGMP host tracking function globally	100
Enabling the IGMP host tracking function on an interface	100
Setting the DSCP value for IGMP messages	100
Configuring IGMP SSM mapping	101
Enabling SSM mapping	101
Configuring SSM mappings	101
Configuring IGMP proxying	101
Enabling IGMP proxying	102
Configuration guidelines	102
Configuration procedure	102
Configuring multicast forwarding on a downstream interface	102
Displaying and maintaining IGMP	103
IGMP configuration examples	104
Basic IGMP functions configuration example	104
Network requirements	104
Configuration procedure	105
Verifying the configuration	106
SSM mapping configuration example	106
Network requirements	106
Configuration procedure	107
Verifying the configuration	108
IGMP proxying configuration example	109
Network requirements	109
Configuration procedure	110
Verifying the configuration	110
Troubleshooting IGMP	111
No membership information on the receiver-side router	111
Symptom	111
Analysis	111
Solution	111
Inconsistent memberships on routers on the same subnet	112
Symptom	112
Analysis	112
Solution	112
Configuring PIM	113
PIM overview	113
PIM-DM overview	113
Neighbor discovery	114
SPT building	114
Graft	115
Assert	115
PIM-SM overview	116
Neighbor discovery	116
DR election	116
RP discovery	117
RPT building	119
Multicast source registration	119
Switchover to SPT	120
Assert	121
Administrative scoping overview	121
Division of PIM-SM domains	121
Relationship between admin-scope zones and the global scope zone	121
PIM-SSM overview	123
Neighbor discovery	123
DR election	123
SPT building	123
Relationships among PIM protocols	124
Protocols and standards	125
Configuring PIM-DM	125
PIM-DM configuration task list	125
Configuration prerequisites	125
Enabling PIM-DM	126
Enabling state-refresh capability	126
Configuring state-refresh parameters	126
Configuring PIM-DM graft retry period	127
Configuring PIM-SM	128
PIM-SM configuration task list	128
Configuration prerequisites	128
Enabling PIM-SM	129
Configuring an RP	129
Configuring a static RP	129
Configuring a C-RP	130
Enabling auto-RP	130
Configuring C-RP timers globally	130
Configuring a BSR	131
Configuring a C-BSR	131
Configuring a PIM domain border	132
Configuring global C-BSR parameters	133
Configuring C-BSR timers	133
Disabling BSM semantic fragmentation	134
Configuring administrative scoping	135
Enabling administrative scoping	135
Configuring an admin-scope zone boundary	135
Configuring C-BSRs for each admin-scope zone and the global-scope zone	136
Configuring multicast source registration	137
Disabling the switchover to SPT	138
Configuring PIM-SSM	138
PIM-SSM configuration task list	138
Configuration prerequisites	138
Enabling PIM-SM	138
Configuring the SSM group range	139
Configuration guidelines	139
Configuration procedure	139
Configuring PIM common features	139
PIM common feature configuration task list	140
Configuration prerequisites	140
Configuring a multicast data filter	140
Configuring a hello message filter	141
Configuring PIM hello options	141
Configuring hello options globally	142
Configuring hello options on an interface	142
Configuring the prune delay	143
Configuring PIM common timers	143
Configuring PIM common timers globally	144
Configuring PIM common timers on an interface	144
Configuring join/prune message sizes	144
Setting the DSCP value for PIM messages	145
Displaying and maintaining PIM	145
PIM configuration examples	147
PIM-DM configuration example	147
Network requirements	147
Configuration procedure	147
Verifying the configuration	148
PIM-SM non-scoped zone configuration example	150
Network requirements	150
Configuration procedure	150
Verifying the configuration	151
PIM-SM admin-scope zone configuration example	154
Network requirements	154
Configuration procedure	156
Verifying the configuration	158
PIM-SSM configuration example	160
Network requirements	160
Configuration procedure	161
Verifying the configuration	162
Troubleshooting PIM	163
A multicast distribution tree cannot be built correctly	163
Symptom	163
Analysis	163
Solution	164
Multicast data abnormally terminated on an intermediate router	164
Symptom	164
Analysis	164
Solution	164
RPs cannot join SPT in PIM-SM	164
Symptom	164
Analysis	165
Solution	165
RPT establishment failure or source registration failure in PIM-SM	165
Symptom	165
Analysis	165
Solution	165
Configuring MSDP	166
Overview	166
How MSDP works	166
MSDP peers	166
Inter-domain multicast delivery through MSDP	167
RPF check rules for SA messages	169
Intra-domain Anycast RP through MSDP	170
Protocols and standards	171
MSDP configuration task list	172
Configuring basic MSDP functions	172
Configuration prerequisites	172
Enabling MSDP	172
Creating an MSDP peer connection	173
Configuring a static RPF peer	173
Configuring an MSDP peer connection	173
Configuring MSDP peer description	174
Configuring an MSDP mesh group	174
Configuring MSDP peer connection control	174
Configuring SA messages related parameters	175
Configuring SA message content	176
Configuring SA request messages	176
Configuring SA message filtering rules	177
Configuring the SA cache mechanism	178
Displaying and maintaining MSDP	178
MSDP configuration examples	179
PIM-SM Inter-domain multicast configuration	179
Network requirements	179
Configuration procedure	180
Verifying the configuration	181
Inter-AS multicast configuration by leveraging static RPF peers	183
Network requirements	183
Configuration procedure	184
Verifying the configuration	187
Anycast RP configuration	187
Network requirements	187
Configuration procedure	188
Verifying the configuration	189
SA message filtering configuration	191
Network requirements	191
Configuration Procedure	192
Verifying the configuration	194
Troubleshooting MSDP	195
MSDP peers stay in down state	195
Symptom	195
Analysis	195
Solution	195
No SA entries in the switch’s SA cache	195
Symptom	195
Analysis	195
Solution	195
Inter-RP communication faults in Anycast RP application	196
Symptom	196
Analysis	196
Solution	196
Configuring MBGP	197
MBGP overview	197
Protocols and standards	197
MBGP configuration task list	197
Configuring basic MBGP functions	198
Controlling route advertisement and reception	198
Configuring MBGP route redistribution	198
Configuring default route redistribution into MBGP	199
Configuring MBGP route summarization	200
Advertising a default route to an IPv4 MBGP peer or peer group	200
Configuring outbound MBGP route filtering	201
Configuring inbound MBGP route filtering	202
Configuring MBGP route dampening	203
Configuring MBGP route attributes	204
Configuring MBGP route preferences	204
Configuring the default local preference	204
Configuring the MED attribute	204
Configuring the NEXT_HOP attribute	205
Configuring the AS_PATH attributes	205
Tuning and optimizing MBGP networks	206
Configuring MBGP soft reset	206
Performing soft reset through route refresh	206
Performing soft reset manually	207
Enabling the MBGP ORF capability	207
Configuring the maximum number of MBGP routes for load balancing	208
Configuring a large scale MBGP network	209
Configuring IPv4 MBGP peer groups	209
Configuring MBGP community	209
Configuring an MBGP route reflector	210
Displaying and maintaining MBGP	211
Displaying MBGP	211
Resetting MBGP connections	212
Clearing MBGP information	212
MBGP configuration example	213
Network requirements	213
Configuration procedure	213
Configuring MLD snooping	217
Overview	217
Basic concepts in MLD snooping	217
MLD snooping related ports	217
Aging timers for dynamic ports in MLD snooping and related messages and actions	218
How MLD snooping works	219
When receiving a general query	219
When receiving a membership report	219
When receiving a done message	219
MLD snooping proxying	220
Protocols and standards	222
MLD snooping configuration task list	222
Configuring basic MLD snooping functions	223
Enabling MLD snooping	223
Specifying the version of MLD snooping	223
Configuration procedure	224
Configuring IPv6 static multicast MAC address entries	224
Configuration guidelines	224
Configuration procedure	224
Configuring MLD snooping port functions	224
Configuring aging timers for dynamic ports	225
Setting the global aging timers for dynamic ports	225
Setting the aging timers for the dynamic ports in a VLAN	225
Configuring static ports	225
Configuring a port as a simulated member host	226
Enabling fast-leave processing	227
Enabling fast-leave processing globally	227
Enabling fast-leave processing on a port	227
Disabling a port from becoming a dynamic router port	227
Configuring MLD snooping querier	228
Enabling MLD snooping querier	228
Configuring parameters for MLD queries and responses	229
Configuring MLD queries and responses globally	229
Configuring the parameters for MLD queries and responses in a VLAN	229
Configuring the source IPv6 addresses for MLD queries	230
Configuring MLD snooping proxying	230
Enabling MLD snooping proxying	230
Configuring the source IPv6 addresses for the MLD messages sent by the proxy	231
Configuring an MLD snooping policy	231
Configuring an IPv6 multicast group filter	231
Configuring an IPv6 multicast group globally	232
Configuring an IPv6 multicast group filer for a port	232
Configuring IPv6 multicast source port filtering	232
Configuring IPv6 multicast source port filtering globally	232
Configuring IPv6 multicast source port filtering for a port	232
Enabling dropping unknown IPv6 multicast data	233
Configuration guidelines	233
Configuration procedure	233
Configuring MLD report suppression	233
Setting the maximum number of multicast groups that a port can join	234
Enabling IPv6 multicast group replacement	234

Match case Limit results 1 per page

104

The flood-and-prune process takes place periodically. A pruned state timeout mechanism is provided. A

pruned branch restarts multicast forwarding when the pruned state times out and then is pruned again

when it no longer has any multicast receiver.

NOTE:

Pruning has a similar implementation in PIM-SM.

Graft

When a host attached to a pruned node joins a multicast group, to reduce the join latency, PIM-DM uses

a graft mechanism to resume data forwarding to that branch. The process is as follows:

The node that needs to receive multicast data sends a graft message toward its upstream node as

a request to join the SPT again.

After receiving this graft message, the upstream node puts the interface on which the graft was

received into the forwarding state and responds with a graft-ack message to the graft sender.

If the node that sent a graft message does not receive a graft-ack message from its upstream node,

it will keep sending graft messages at a configurable interval until it receives an acknowledgment

from its upstream node.

Assert

Where more than one multicast router exists, the assert mechanism shuts off duplicate multicast flows

onto the same multi-access network. It does this by electing a unique multicast forwarder on the

multi-access network.

Figure 37

Assert mechanism

As shown in

Figure 37

, after Router A and Router B receive an (S, G) packet from the upstream node, they

both forward the packet to the local subnet. As a result, the downstream node Router C receives two

identical multicast packets, and both Router A and Router B, on their own downstream interface, receive

a duplicate packet forwarded by the other. After detecting this condition, both routers send an assert

message to all PIM routers (224.0.0.13) on the local subnet through the downstream interface on which

the packet was received. The assert message contains the multicast source address (S), the multicast

group address (G), and the preference and metric of the unicast route/MBGP route/multicast static route

to the source. By comparing these parameters, either Router A or Router B becomes the unique forwarder

of the subsequent (S, G) packets on the multi-access subnet. The comparison process is as follows:

The router with a higher preference to the source wins;

If both routers have the same preference to the source, the router with a smaller metric to the source

wins;

HP 6125G HP 6125G &amp; 6125G/XG Blade Switches IP Multicast Configuration - Page 115

Graft, Assert, Assert mechanism

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HP 6125G HP 6125G & 6125G/XG Blade Switches IP Multicast Configuration - Page 115