CCIE R&S Advanced Technologies Class v4.5

Transcript

1	Introduction	0h 43m
2	Using the Cisco Documentation	0h 52m
3	Ethernet Overview, Layer 2 Switchports, Trunking, ISL, 802.1q, DTP	0h 47m
4	VTP, VTP Authentication, VTP Pruning	1h 02m
5	VTP Prune Eligible List, VTP Transparent, VTP Troubleshooting, Trunk Allowed List, Extended VLANs	0h 48m
6	VLAN and VTP Review	0h 19m
7	SVIs, Native Routed Interfaces, Router-on-a-Stick	0h 46m
8	Layer 2 EtherChannel, EtherChannel Load Balancing, Layer 3 EtherChannel	0h 57m
9	802.1q Tunneling, Layer 2 Protocol Tunneling, EtherChannel over 802.1q Tunneling	1h 03m
10	STP Root Bridge Election, STP Root Port Election, STP Designated Port Election, STP Priority, STP Cost, STP Port-Priority	1h 46m
11	STP Review	0h 12m
12	STP Timers, STP PortFast	0h 34m
13	STP UplinkFast	0h 11m
14	STP BackboneFast	0h 12m
15	STP BPDU Filter	0h 13m
16	STP BPDU Guard	0h 11m
17	STP Root Guard	0h 11m
18	STP Loop Guard, Unidirectional Link Detection (UDLD)	0h 11m
19	Multiple Spanning-Tree Protocol (MST)	0h 40m
20	Rapid Spanning-Tree Protocol (RSTP), Rapid-PVST	0h 18m
21	MST with Multiple Regions	0h 33m
22	Flex Links	0h 16m
23	Frame Relay	0h 39m
24	Frame Relay Configuration Part 1	0h 34m
25	Frame Relay Configuration Part 2	0h 41m
26	Frame Relay Switching	0h 27m
27	Back-to-Back Frame Relay	0h 08m
28	Frame-Relay End-to-End Keepalives	0h 18m
29	PPP, PPP PAP Authentication, PPP CHAP Authentication	0h 59m
30	PPPoFR, PPPoE	0h 40m
31	Transparent Bridging, IRB	0h 32m
32	Fallback Bridging	0h 14m
33	IP Routing Overview, Switching Paths, Static Routing	0h 42m
34	Static Routing Examples	0h 25m
35	IP Default-Gateway, IP Default-Network	0h 14m
36	On-Demand Routing (ODR)	0h 07m
37	Floating Static Routes	0h 10m
38	Backup Interface	0h 29m
39	Enhanced Object Tracking, IP SLA, Reliable Static Routing	0h 21m
40	Policy Routing	0h 43m
41	GRE Tunneling, GRE Recursive Routing Errors	0h 27m
42	Reliable Backup Interface with GRE	0h 25m
43	RIP Overview, RIP Versions, RIP Auto-Summary	0h 48m
44	RIP Split-Horizon, RIP Timers	0h 22m
45	RIP Broadcast Updates, IP Directed Broadcast, IP Broadcast-Address, Smurf Attacks, Fraggle Attacks	0h 16m
46	RIP Unicast Updates	0h 03m
47	RIP Offset-List	0h 18m
48	RIP Authentication	0h 11m
49	RIP Summarization	0h 10m
50	Prefix-Lists, RIP Distribute-List Filtering, RIP Administrative Distance Filtering	0h 48m
51	RIP Default Routing, RIP Conditional Default Routing	0h 18m
52	RIP Triggered, RIP Validate Update Source,	0h 12m
53	EIGRP Overview	0h 29m
54	EIGRP Auto-Summary	0h 07m
55	EIGRP Split-Horizon	0h 11m
56	EIGRP Update Types, EIGRP Neighbor, EIGRP Passive-Interface	0h 24m
57	EIGRP Hello-Interval, EIGRP Hold-Time	0h 05m
58	EIGRP Authentication	0h 11m
59	EIGRP Time Based Authentication	0h 25m
60	EIGRP Path Selection, EIGRP Metric Weights, EIGRP Traffic Engineering	0h 47m
61	EIGRP Unequal Cost Load Balancing, EIGRP Variance	0h 19m
62	EIGRP QUERY, EIGRP Summarization, EIGRP Leak-Map	0h 28m
63	EIGRP Stub Router Advertisement	0h 22m
64	EIGRP Default Routing	0h 13m
65	EIGRP Route Filtering	0h 11m
66	EIGRP Router-ID	0h 07m
67	Miscellaneous EIGRP Features	0h 02m
68	OSPF Overview	0h 27m
69	Establishing OSPF Adjacencies, Understanding the OSPF Database	0h 43m
70	OSPF Network Type Broadcast, OSPF DR/BDR Election, OSPF over NBMA, OSPF Network Type Non-Broadcast and Point-to-Multipoint	0h 56m
71	OSPF Network Type Point-to-Point, OSPF Network Type Mismatch	0h 13m
72	OSPF Network Type Point-to-Multipoint Non-Broadcast, OSPF Per Neighbor Cost	0h 17m
73	OSPF Network Type Loopback	0h 02m
74	OSPF Path Selection	0h 27m
75	OSPF Convergence Timers	0h 09m
76	OSPF Authentication	0h 12m
77	OSPF Summarization	0h 32m
78	OSPF Stub Areas, OSPF Totally Stubby Areas, OSPF NSSAs, OSPF Totally NSSAs	0h 40m
79	Controlling OSPF NSSA Redistribution	0h 02m
80	OSPF Type 7 to 5 Translator Election, OSPF LSA Type 3 Filter, OSPF Forwarding Address Suppression	0h 24m
81	Route Redistribution Overview	0h 36m
82	Route Redistribution Configuration & Verification, Connected Redistribution	0h 22m
83	OSPF External Path Selection, TCL PING Scripting	0h 33m
84	Routing Loops Overview, EIGRP Route Loop Prevention	0h 55m
85	Metric Based Routing Loops, Route Tagging	0h 46m
86	Administrative Distance Based Routing Loops, Debug IP Routing, IP Route Profile	0h 58m
87	BGP Overview, BGP Peering Types	0h 51m
88	Establishing BGP Peerings, EBGP Multihop, BGP Neighbor Disable Connected Check, BGP TTL Security	0h 49m
89	BGP 4-Byte ASNs	0h 20m
90	BGP Local AS, BGP Peer Groups	0h 30m
91	BGP Next-Hop Self, BGP Next-Hop Processing	0h 30m
92	BGP Route Reflectors	0h 37m
93	Large Scale BGP Route Reflectors with Clusters	0h 34m
94	BGP Confederation	0h 37m
95	BGP NLRI Advertisements, BGP Network Statement, BGP Redistribution	0h 43m
96	BGP Aggregation, BGP Aggregation & Summary-Only, BGP Aggregation & Unsuppress-Map	0h 46m
97	BGP Origin, BGP Aggregation & AS-Set, BGP Aggregation & Advertise-Map	0h 22m
98	BGP Conditional Route Injection	0h 21m
99	BGP Bestpath Selection, BGP Multipath, BGP Weight	0h 53m
100	BGP Local Preference, BGP Local Preference and Communities, BGP AS-Path Prepending,	0h 30m
101	BGP MED, BGP MED Missing As Worst, BGP Deterministic MED	0h 17m
102	BGP Communites, BGP Regular Expressions	0h 43m
103	BGP Filtering, BGP Convergence Timers, BGP Default Routing, Miscellaneous BGP Features	0h 24m
104	MPLS Overview, MPLS Label Distribution Protocol (LDP)	1h 05m
105	MPLS Tunnels, MPLS Penultimate Hop Popping (PHP)	0h 40m
106	MPLS Layer 3 VPNs Overview, VRF Lite	0h 36m
107	MPLS Layer 3 VPNs and VPNv4 BGP	1h 08m
108	MPLS Layer 3 VPN Verification & Troubleshooting	0h 49m
109	MPLS Layer 3 VPN OSPF PE-CE Routing Overview	0h 06m
110	MPLS Layer 3 VPN OSPF PE-CE Routing Path Selection & Sham-Links	2h 01m
111	MPLS Layer 3 VPN OSPF PE-CE Routing Loop Prevention & Down-Bit, OSPF Capability VRF-Lite	0h 40m
112	IPv6 Overview, IPv6 ICMPv6 ND, IPv6 over NBMA	0h 44m
113	IPv6 Routing Overview, IPv6 Static Routing	0h 28m
114	IPv6 RIPng	0h 20m
115	IPv6 EIGRPv6	0h 09m
116	IPv6 OSPFv3	0h 31m
117	MP-BGP for IPv6	0h 26m
118	IPv6 Tunneling	1h 13m
119	Multicast Overview, IGMP	0h 34m
120	PIM Overview	0h 18m
121	PIM Dense Mode	1h 03m
122	PIM Sparse Mode	0h 30m
123	PIM Sparse Mode Configuration	0h 36m
124	PIM Sparse Mode RPF & RP Troubleshooting	0h 27m
125	Auto-RP, Multicast over GRE Tunnels	0h 53m
126	Bootstrap Router (BSR), Bidirectional PIM, Source Specific Multicast (SSM)	0h 40m
127	MSDP, Anycast RP	0h 27m
128	IPv6 Multicast Routing	0h 24m
129	QoS Overview, IntServ QoS, DiffServ QoS, IP Precedence, DSCP, MQC, HQF	0h 41m
130	MQC Classification	0h 44m
131	FIFO, FQ, WFQ, CBWFQ, HQF	0h 50m
132	LLQ	0h 23m
133	WRED	0h 31m
134	Traffic Shaping, Traffic Policing	0h 40m
135	Frame Relay Traffic Shaping (FRTS)	0h 33m
136	RSVP	0h 07m
137	Catalyst 3560 QoS	1h 00m
138	IOS Security Overview, Access Lists (ACLs)	0h 58m
139	Time Based ACLs, Dynamic ACLs	0h 33m
140	Reflexive ACLs	0h 21m
141	TCP Intercept, Content Based Access Control (CBAC)	0h 34m
142	Zone Based Policy Firewall (ZBPF)	1h 09m
143	AAA, Local Authentication, Local Authorization, Role Based CLI Access	0h 43m
144	Port Security, Static CAM Entries, Storm Control, 802.1X Authentication, PACLs, RACLs, VLAN Access Maps (VACLs)	0h 48m
145	DHCP Snooping, Dynamic ARP Inspection (DAI), IP Source Guard	0h 12m
146	Protected Ports, Private VLANs	0h 25m
147	IP Services Overview, HSRP	1h 10m
148	VRRP, GLBP	0h 28m
149	NAT	0h 42m
150	DHCP, DNS	0h 30m
151	NetFlow	0h 09m
152	WCCP, Miscellaneous IP Services	0h 06m
153	System Management Overview, NTP, NTP Authentication	0h 24m
154	SNMP, RMON	0h 38m
155	Syslog, Telnet, SSH, Banners	0h 21m
156	EEM Scripting, Miscellaneous System Management	0h 26m
Total Duration		81h 42m

Slides - Diagrams

Slides - Introduction

Slides - Ethernet Switching

Slides - Advanced Ethernet Switching

Slides - Frame Relay

Slides - PPP

Slides - Transport Bridging

Slides - Redistribution

Slides - IOS Security

Slides - Layer 2 Security

Slides - IP Services

Slides - System Management

0:00:12	In our next section here for multicast, we're going to look at
0:00:15	running PIM in sparse mode which as opposed to dense mode
0:00:20	is considered an explicit join since traffic is not
0:00:24	going to be sent anywhere in the network unless it is requested.
0:00:28	Now in addition to having no flooding and pruning behavior like
0:00:31	dense mode does, there's another large difference between sparse mode
0:00:35	and dense mode in the fact that sparse mode uses both shared trees
0:00:40	and source based trees. For PIM in dense mode
0:00:44	we are only using source based trees which are also considered
0:00:48	the shortest path tree.
0:00:51	In sparse mode we have the shared trees which is also
0:00:54	sometimes called the rendezvous point tree or the RPT.
0:00:59	In general, sparse mode is going to be more scalable
0:01:01	than dense mode and is usually the better design choice
0:01:04	we'll also see there's another variation of sparse mode for
0:01:07	source specific multicast that does not use shared trees
0:01:11	and only uses source based trees, but the vast majority of
0:01:15	the logic for sparse mode whether we're running in source
0:01:19	specific or in regular sparse mode is going to be similar.
0:01:23	Just like PIM in dense mode, this is a standards based protocol
0:01:26	it's defined in RFC 4601 so if you search that
0:01:30	you can get as I mentioned the packet level format information
0:01:33	or if you need any of the real detailed information about
0:01:37	how sparse mode is supposed to build the multicast routing table
0:01:41	then that's going to be available in the RFC.
0:01:46	Now the main difference between the shared tree and the source based
0:01:50	tree is going to control how traffic is delivered from
0:01:54	the source to the destination and additionally what devices
0:01:58	in the network it is going to be routed through.
0:02:01	In the case of a source based tree or the SPT
0:02:05	traffic is routed from the sender to the receiver
0:02:09	based on the unicast route from the receiver back to the source.
0:02:15	So again, this is the opposite of normal unicast routing
0:02:18	where in unicast we're taking traffic as it comes in
0:02:21	from a sender and routing it to the destination based on
0:02:25	the route to the destination where in the case of multicast
0:02:29	we are receiving traffic on the receiver from the source
0:02:34	based on the receiver's route back to the source.
0:02:38	So we're essentially doing reverse path routing or
0:02:40	source routing for multicast.
0:02:42	Now the second variation of trees which is the shared tree
0:02:46	or the rendezvous point tree
0:02:49	this is the shortest path from the receiver
0:02:52	to the rendezvous point.
0:02:54	So in the case of the shared tree, we're actually going to have
0:02:57	two separate trees, one that goes from the device that is
0:03:00	sending up to the rendezvous point, then from the
0:03:03	rendezvous point down to the receiver.
0:03:06	So from the receiver to the RP, that is considered the
0:03:10	RPT, the rendezvous point's tree.
0:03:12	From the rendezvous point to the sender, that is a
0:03:16	shortest path tree.
0:03:18	Now we'll see that also one of the differences here
0:03:21	is that the reverse path forwarding check will change
0:03:25	depending on whether the tree is a source based tree
0:03:28	or whether it is a shared tree.
0:03:33	Now the operation or sparse mode is going to be more
0:03:36	more complicated than dense mode is where in dense mode
0:03:40	basically we had those four steps of just discovering the
0:03:43	neighbors, flooding the traffic everywhere, pruning it on the
0:03:46	links that we didn't want and then the basic routing table maintenance
0:03:50	which would be the assert messages, the grapt messages
0:03:54	and then the state refresh.
0:03:56	Now in the case of sparse mode, we will now need a
0:04:02	rendezvous point to figure out who are all the senders
0:04:05	in the network and who are all the receivers.
0:04:08	So the rendezvous point is going to be the route
0:04:11	of the RPT
0:04:13	and it is going to build a shortest path tree
0:04:16	back to all of the senders.
0:04:19	Now we'll see that there's a fundamental difference
0:04:21	when we look at the show ip mroute output
0:04:23	from the sparse mode network versus the dense mode network
0:04:27	where in the case of dense mode, all routers in the network will
0:04:32	know about all S,G entries
0:04:35	and for any receiver that has no source, only
0:04:40	the very last hop router would know about that.
0:04:44	So previously in the case of Router 4, we saw that
0:04:47	when it joined the group by issuing the ip igmp join group command at the
0:04:51	interface and there was no one actually sending the traffic
0:04:55	Router 4 was the only one that installed the *,G entry.
0:05:00	But in the case of sparse mode, we'll see that the rendezvous point
0:05:03	needs to know about all senders, but also all receivers.
0:05:08	So there's two separate processes we need to go through
0:05:10	to figure out on the rendezvous point who are the sources
0:05:13	and then who are the receivers.
0:05:16	Once we do that, then we can actually build the tree
0:05:18	from the sender down to the rendezvous point, from the
0:05:22	rendezvous point to the receiver, then optionally optimize the path
0:05:26	by joining the shortest path tree and then leaving the shared tree.
0:05:33	So from a verification and a troubleshooting point of view
0:05:35	the key is that we need to understand how all of these
0:05:38	individual steps work because there's different problems that
0:05:41	can happen during the discovering if the PIM neighbors
0:05:44	versus finding the rendezvous point
0:05:46	versus figuring out who are the sources, who are the receivers.
0:05:51	Now there's a question here, "Is the shared tree the leg
0:05:53	from the RP to the receiver?" Correct. So if we were to
0:05:57	visualize this from the point of the diagram
0:06:00	let's say that Router 1 is the rendezvous point for the network.
0:06:04	If we have a sender
0:06:08	that is on VLAN 9 and a receiver so the client
0:06:13	that is on VLAN 10
0:06:15	we should see on VLAN 10 that the IGMP join message
0:06:19	is going to come in from the host, Switch 4 is then going to
0:06:23	turn this into a PIM join.
0:06:27	The PIM join goes up the reverse path tree to the
0:06:30	rendezvous point in order to build the *,G tree
0:06:35	which is the rendezvous point tree or the shared tree.
0:06:43	So this portion over here on the right this is the shared tree.
0:06:48	Then from the rendezvous point once it figures out who the sender is
0:06:52	it is going to build its own shortest path tree
0:06:56	or essentially the S,G tree
0:06:59	back to the sender.
0:07:03	Now whether or not there's going to be an S,G built from the
0:07:06	sender all the way down to the receiver, it's going to depend on
0:07:08	a couple different options that we can configure.
0:07:11	But normally when the traffic is flowing through the rendezvous point
0:07:14	the shortest path tree goes from the RP to the sender
0:07:19	and the shared tree goes from the receiver back to the rendezvous point.
0:07:25	Now since the rendezvous point is going to be the reference in the
0:07:28	network for this shared tree, it means that it needs to
0:07:31	figure out who are the sources and who are the destinations.
0:07:36	To figure out the sources we have a new message
0:07:39	specific to sparse mode that is called the register message.
0:07:43	The register is going to be sent from the designated router
0:07:47	on the LAN to the rendezvous point
0:07:50	telling them about an individual S,G entry.
0:07:55	So in this particular design, if the sender was located
0:07:58	on Switch 3's LAN segment
0:08:01	as the packets came in from them, Switch 3 would send a
0:08:05	register message to Router 1
0:08:07	saying that I know about this particular S, G entry.
0:08:12	If Router 1 accepts that, it's going to reply back to
0:08:14	them with a register stop message saying I'm
0:08:19	acknowledging that you know about the sender, but at this point
0:08:22	I don't yet have any receivers.
0:08:26	So in order to make sure that the first portion of the network is
0:08:28	working that the rendezvous point knows about the senders
0:08:32	we need to make sure that the registration process happens.
0:08:38	The second portion of the tree which is the RPT
0:08:42	or the shared tree
0:08:44	this is built by the devices from the receiver back up to
0:08:48	the rendezvous point sending the PIM join messages.
0:08:53	And the goal of the join messages is to tell the router upstream
0:08:57	that you need to add my interface to your outgoing
0:09:00	interface list for the *,G entry.
0:09:04	So in our particular topology here if the IGMP client is
0:09:09	on VLAN 10, it's going to send the report message
0:09:13	into Switch 4
0:09:14	basically saying I want traffic for this particular group.
0:09:21	So this is either an IGMP version 2 report message
0:09:25	or an IGMP version 3 report that does not specify who the source is.
0:09:31	Once Switch 4 knows about the particular group
0:09:34	it doesn't yet know who the sender is.
0:09:37	So it needs to tell the rendezvous point that
0:09:39	I now have a receiver, but I don't know where the traffic is
0:09:42	going to come from.
0:09:44	So to do this, what Switch 4 does is look at what is the
0:09:47	route that I use to get to Router 1
0:09:50	so again, this is assuming that IGP is working underneath.
0:09:54	If Switch 4 doesn't have a route to Router 1
0:09:56	then it's not going to know where to send the PIM message.
0:10:01	So assuming that routing is correct, Switch 4 says to get to Router 1
0:10:04	I'm going to need to go towards Switch 2
0:10:07	so this means that it's going to turn around and send a
0:10:09	PIM join.
0:10:12	The goal of this message is to get Switch 2
0:10:15	to add the port channel interface to the outgoing
0:10:20	interface list for that particular *,G entry.
0:10:25	Then likewise, Switch 2 is going to send this join to 5
0:10:28	5 is going to send it to 1
0:10:33	so what this means is that if we have a receiver in the network
0:10:38	everywhere in the path from the receiver back to the
0:10:40	rendezvous point we should see the *,G entry installed
0:10:44	in the routing table.
0:10:47	From the designated router which is attached to the sender
0:10:51	up to the rendezvous point we are going to see the
0:10:54	S, G entry on the DR plus the rendezvous point
0:10:58	but no one else in the network unless we're actually
0:11:01	sending the traffic down to a receiver.
0:11:07	So we'll see based on these two principles of how the
0:11:10	tree is built from the receiver back to the RP and from the RP
0:11:13	back to the sender. There's a couple quick verifications
0:11:16	that we can do to figure out if the receiving portion of the
0:11:19	tree and then the sending portion of the tree are correct.
0:11:23	Now as I mentioned for the rendezvous point to figure out who
0:11:25	the sources are, this is what the register message
0:11:29	is used for from the designated router attached to the
0:11:33	sender. Now a key point of the multicast design to
0:11:37	understand here is that the actual server that is
0:11:40	sending the feed like the IPTV server
0:11:43	it does not run multicast routing
0:11:45	it's simply blindly sending the traffic out onto the LAN.
0:11:51	Now when the router who is running multicast hears that
0:11:53	inbound, if that router is the designated router
0:11:59	then it's going to tell the rendezvous point I now know
0:12:01	about this particular sender in the network.
0:12:04	Now if there's only one router on the segment
0:12:07	by default, it's going to be the DR. It's only at the case that there are
0:12:11	multiple first hop routers on the LAN that there's going to be an
0:12:14	election process to figure out who is supposed to tell
0:12:17	the rendezvous point about the source.
0:12:20	Now if the rendezvous point accepts this message
0:12:23	it's going to acknowledge it with a register stop
0:12:26	and put the S, G into the routing table.
0:12:30	So what this means is that once we start to send the traffic
0:12:33	we should be able to go to the rendezvous point and
0:12:36	look at the show ip mroute for the particular source
0:12:39	and group and if that is not installed in the routing table
0:12:43	it means there's something wrong with the registration process.
0:12:49	Now on the other end we have the end client
0:12:53	sending the IGMP join this is then going to get
0:12:57	converted into a PIM join to go back up
0:12:59	the RPT, so if we were to go to Switch 4 in this particular
0:13:05	topology
0:13:06	go to VLAN 10 and say ip igmp join 224.1.1.4
0:13:13	we should be able to go to Switch 4 to Switch 2
0:13:15	to Router 5 and Router 1
0:13:18	look at the show ip mroute for that particular group
0:13:21	and see the *,G installed.
0:13:24	If the *,G is not installed, it either means that someone
0:13:29	does not know about the rendezvous point
0:13:32	or they don't have the correct reverse route to the rendezvous point.
0:13:37	So maybe Switch 2 knows that Router 1's loopback
0:13:40	is supposed to be the RP, but if it doesn't have a route
0:13:43	to the loopback of Router 1 then it's not going to be able to
0:13:46	send the PIM join message
0:13:48	or if Router 1 doesn't know that itself is the rendezvous point
0:13:53	so if we don't have the ip pim rp address command
0:13:56	on Router 1, then it would not accept the join message
0:13:59	to come in.
0:14:01	So we'll see depending on whether we're talking about the
0:14:04	sender's portion of the tree or the receiver's portion of the tree
0:14:07	there's separate verifications and troubleshooting that we need to use.
0:14:11	But the key is that within the scope of the lab exam
0:14:14	since we're trying to do this troubleshooting so quickly
0:14:16	within the limited time frame, we basically need to know
0:14:20	how every piece of the puzzle fits together
0:14:23	and if there's a problem with the rendezvous point
0:14:26	installing the S, G versus installing the *,G
0:14:29	we need to know exactly where to look, so do I want to
0:14:33	look towards the receiver or do I want to look towards the
0:14:35	sender, what are the different show commands, what are the different
0:14:38	debug commands that I can do.
0:14:40	We'll see once the rendezvous point knows about both
0:14:43	the sender and the receiver, then it's going to merge these
0:14:45	two trees together.
0:14:48	The way it's going to do this is by sending its own
0:14:50	PIM join messages up the reverse path towards the source.
0:14:55	This is then where the rendezvous point is joining the shortest path
0:14:58	tree back to the source.
0:15:01	So in this case, the third portion of building the tree
0:15:05	would mean that Router 1 says two things.
0:15:10	It's going to say I know about the sender
0:15:12	which is the * -- or excuse me, the S, G
0:15:17	the S, G that was reported to me by Switch 3 via
0:15:22	the register message.
0:15:27	I'm then going to acknowledge to them with the register stop
0:15:30	saying I know about the particular source.
0:15:33	Then we have the IGMP join come in from the client.
0:15:37	Switch 4 turns this into a PIM join
0:15:40	it goes up the reverse path to the rendezvous point
0:15:43	the rendezvous point now knows about the *,G
0:15:50	so now Router 1 knows about both the sender and the receiver.
0:15:53	Next thing is that it is going to join the
0:15:56	shortest path tree back to the source.
0:15:58	So it sends the PIM join
0:16:03	to Router 3
0:16:04	telling I want to join this particular S, G
0:16:09	3 then should send the join to Switch 1
0:16:11	Switch 1 installs the S, G sends it to Switch 3
0:16:15	Switch 3 should update its outgoing interface list
0:16:19	saying I'm now actually forwarding on that VLAN.
0:16:23	Once the traffic gets down to the rendezvous point
0:16:27	so now the traffic actually starts to flow to Router 1
0:16:31	when Router 1 receives it on the shortest path tree
0:16:34	it's merges this with the shared tree.
0:16:39	So from the rendezvous point's perspective, the traffic is coming
0:16:42	in the SPT, but it's going out the RPT
0:16:47	so it's coming in the shortest path tree, but going out the
0:16:50	shared tree.
0:16:51	Once eventually this gets down to Switch 4
0:16:54	Switch 4 can then decide do I want to leave the
0:16:58	shared tree and join the shortest path tree
0:17:02	this is ultimately the optimization of what the traffic flow is going to be.
0:17:08	So the traffic is now going end to end because the
0:17:11	rendezvous point merges those two trees together
0:17:14	then the last hop router is going to have the option to
0:17:18	optimize the traffic flow.
0:17:21	So the key about the rendezvous point in the sparse mode network
0:17:24	it doesn't necessarily have to be in the data plane forwarding
0:17:28	for the actual flow.
0:17:30	It's basically used just as a control plane mechanism to
0:17:34	build the two trees. Once they're built, the very last
0:17:38	hop router can switch over to the shortest path tree
0:17:41	and remove the rendezvous point out of the traffic flow.
0:17:47	So if in our particular design if we were to say that
0:17:51	maybe Router 1 is not the rendezvous point
0:17:54	but let's say Router 2 is the RP
0:18:00	If Router 2 is the RP and the sender
0:18:05	is coming from Router 4
0:18:07	and the receiver is on Router 5
0:18:13	we know that the optimal flow is not going to be
0:18:15	from Router 4 to 2 and then 2 back to 5
0:18:20	ideally we would want the traffic just to go this direction
0:18:23	directly from 4 to 5
0:18:26	but the problem is once we're going from the sender to the
0:18:29	rendezvous point and the rendezvous point down to the
0:18:32	receiver, by default that's how the tree is going to be built
0:18:36	because the rendezvous point says my shortest path tree
0:18:40	is coming in this way, then the receiver is saying
0:18:45	my rendezvous point tree, the RPT or the shared tree,
0:18:49	is going this way.
0:18:54	So in the case where the rendezvous point is not in the
0:18:57	actual data flow for the shortest path
0:19:00	then the last hop router is automatically going to
0:19:03	optimize the flow. Now we can control this in the IOS
0:19:06	there's a command that is the IP PIM SPT threshold
0:19:12	so by default this is immediately it's basically one packet
0:19:15	as soon as we receive the traffic in on the rendezvous point tree
0:19:20	we're going to join the shortest path tree and
0:19:23	then leave the RPT
0:19:28	Now there can potentially be some design issues with this
0:19:31	and we'll see a case where there is a correct building
0:19:35	of the shared tree, but then an incorrect building
0:19:39	of the shortest path tree
0:19:42	and typically the way that we see that on the command line
0:19:45	is that if we're doing a ping from the source to the destination
0:19:48	the first couple packets go through and then the rest
0:19:52	of the feed dies.
0:19:55	So if I were to ping from Switch 3 to the group that
0:19:59	Switch 4 is joining and I see that the first couple
0:20:02	packets go through, but then the rest of them
0:20:04	are dropped. Generally, this is an indication of a failure
0:20:07	to switch over properly to the shortest path tree.

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CCIE R&S Advanced Technologies Class v4.5
Title:	CCIE R&S Advanced Technologies Class v4.5
Duration:	81h 42m
The CCIE Routing & Switching Advanced Technologies Class is the first step in understanding CCIE level technologies and is a companion to the Advanced Technologies Lab Workbook. Each technology you need to know for the CCIE Routing & Switching lab will be described in detail using an instructor led hands on demonstration. The class consists of over 80 hours of in depth explanations and examples.
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PIM Sparse Mode

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