Upload
haris-muhammad
View
147
Download
18
Embed Size (px)
Citation preview
1© 2001, Cisco Systems, Inc.
IP Multicast OverviewIP Multicast OverviewIP Multicast OverviewIP Multicast Overview
Cisco Advanced ServicesCisco Advanced ServicesCisco Advanced ServicesCisco Advanced Services
2© 2002, Cisco Systems, Inc. IP Multicast Basics
AgendaAgenda
• Part 1 - Basic IP Multicast– Multicast Applications, Network Components,
Addressing, IGMP
– Multicast Routing at a High Level
• Part 2 - Configuration Example
• Part 3 - RP Details– Auto-RP, BSR, Anycast
3© 2002, Cisco Systems, Inc. IP Multicast Basics
Part 1 – Basic IP MulticastPart 1 – Basic IP Multicast
• Why IP Multicast?– When sending same data to multiple receivers
– Better bandwidth utilization• Send traffic to where it needs to go
– Less host/router processing
– Receivers’ addresses unknown
– Trade-off is state creation and maintenance
• Challenges with IP Multicast– Configuration is generally easy
– Troubleshooting is relatively more complex• Need to worry about state creation and flags• Concern is where the packet came from versus where the packet
is going in unicast
4© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast ApplicationsMulticast Applications
Corporate BroadcastsCorporate Broadcasts
Distance LearningDistance Learning
TrainingTraining
Video Conferencing
Video Conferencing
Whiteboard/Collaboration
Whiteboard/Collaboration
Multicast File Transfer
Multicast File TransferData and File Replication
Data and File Replication
Real-Time Data Delivery—FinancialReal-Time Data Delivery—Financial
Video-On-Demand
Video-On-Demand
Live TV and Radio Broadcast Live TV and Radio Broadcast to the Desktopto the Desktop
5© 2002, Cisco Systems, Inc. IP Multicast Basics
Nature of Multicast ApplicationsNature of Multicast Applications
• Usually UDP based– So, no TCP windowing / slow-start
– WRED does not apply
• Duplicate Delivery– During some transition periods, duplicate packet delivery
can occur
• Reliable Multicast
6© 2002, Cisco Systems, Inc. IP Multicast Basics
Interdomain MulticastInterdomain MulticastCampus MulticastCampus Multicast
Multicast Network ComponentsMulticast Network Components
• End Stations (hosts-to-routers):– IGMP
• Switches (Layer 2 Optimization):– CGMP, IGMP Snooping or RGMP
• Routers (Multicast Forwarding Protocol):
– PIM Sparse Mode or Bidirectional PIM
• Multicast routing across domains– MBGP
• Multicast Source Discovery– MSDP with PIM-SM
• Source Specific Multicast– PIM-SSM
ISP B
Multicast SourceY
ISP A
Multicast SourceX
ISP B
DRRP
RP
DRDRIGMP PIM-SM
CGMPMBGP
MSDP
ISP A
7© 2002, Cisco Systems, Inc. IP Multicast Basics
GroupMember 2
“Non” GroupMember
Group Member 1
B
E
A D
C
Group Member 3
Multicast Network ComponentsMulticast Network Components
1. If you send to group address, all members receive it
2. You must be a “member” of a group to receive data
3. You do not have to be
a member of a group to send to a group
8© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast Network Components for AT&T’s MVPN Service
Multicast Network Components for AT&T’s MVPN Service
Customer PIM Adjacency
CE
CE
CE
Global Multicast
Customer PIM Adjacency
CustomerPIM Adjacency
VRF
mVRF PE
PE
PE PGlobal
SPs RP
Customer’s RP
Source
Receiver
SP PIM Adjacency
9© 2002, Cisco Systems, Inc. IP Multicast Basics
• IP Multicast Group Addresses– 224.0.0.0 – 239.255.255.255– Class “D” Address Space
• High order bits of 1st Octet = “1110”• Reserved Link-local Addresses
– 224.0.0.0 – 224.0.0.255 (used typically by routing protocols)– Transmitted with TTL = 1 (not forwarded by routers)– Examples:
• 224.0.0.1 All systems on this subnet• 224.0.0.2 All routers on this subnet• 224.0.0.9 RIPv2• 224.0.0.5 OSPF routers• 224.0.0.13 ALL PIM ROUTERS
• Other Reserved Addresses – 224.0.1.0 – 224.0.1.255 (forwarded by routers, e.g. Auto-RP)
Multicast Addressing Multicast Addressing
10© 2002, Cisco Systems, Inc. IP Multicast Basics
• Administratively Scoped Addresses
– Same as RFC 1918 addresses• 239.0.0.0 – 239.255.255.255
– Used to limit “scope” of multicast traffic
– Configured via “ip multicast boundary…” on an interface• multicast traffic with the group range specified cannot enter or leave the
network
– Example – ABC Inc. with Divisions A and B
• Both A and B use 239.255.0.0/16 range of addresses
• Boundary routers in A and B are configured with these addresses as
administrative boundaries
– A and B reuse the same group addresses but cannot talk to each other
• ABC Inc. uses 239.0.0.0/8 boundary company wide
Multicast Addressing Multicast Addressing
11© 2002, Cisco Systems, Inc. IP Multicast Basics
• Can use TTL thresholds on router interfaces to contain multicast forwarding
– S0 is RPF interface
– S1, S2, E0 are in OIL
– S2 and E0 have TTL threshold = 0
– S1 TTL threshold = 100
• Packet will be forwarded on S2 and E0, not S1
– Forward if, current TTL (4) >
configured threshold
– Else, drop.
Side Topic – Using TTL Side Topic – Using TTL
E0
S1
S0
S2
Multicast Packet arrives with
TTL=5
12© 2002, Cisco Systems, Inc. IP Multicast Basics
H3
• Host sends IGMP Report to join group
• There are several IGMP versions – 1,2,3
• Useful on routers for testing multicast forwarding
– Specify “ip igmp join-group X” on a loopback interface to
simulate a receiver
H3224.1.1.1
Report
H1 H2
Joining a Group
Receivers Announce Their PresenceReceivers Announce Their Presence
13© 2002, Cisco Systems, Inc. IP Multicast Basics
Shortest Path or Source Distribution Tree
Receiver 1
B
E
A D F
Source 1Notation: (S, G) S = Source G = Group
C
Receiver 2
Source 2
Multicast Routing – High LevelMulticast Routing – High Level
14© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast Routing – High LevelMulticast Routing – High Level
Shared Distribution Tree
Receiver 1
B
E
A F
Notation: (*, G) * = All Sources G = Group
C
Receiver 2
(RP) PIM Rendezvous Point
Shared Tree
D (RP)
15© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast Routing – High LevelMulticast Routing – High Level
Shared and Source Trees
Receiver 1
B
E
A F
Source 1 Notation: (*, G) * = All Sources G = Group
C
Receiver 2
Source 2
(RP) PIM Rendezvous Point
Shared Tree
Source Tree
D (RP)
16© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast Routing – High LevelMulticast Routing – High Level
• Source or Shortest Path trees
Uses more memory O(S x G) but you get optimal
paths from source to all receivers; minimizes delay
• Shared trees
Uses less memory O(G) but you may get sub-
optimal paths from source to all receivers; may
introduce extra delay
CharacteristicsCharacteristics of Distribution Trees
17© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast Routing – High LevelMulticast Routing – High Level
• What is RPF?What is RPF?A router forwards a multicast datagram only if received on the up stream interface to the source (i.e. it follows the distribution tree).
• The RPF CheckThe RPF Check• The routing table used for multicasting is checked against the “source” IP address in the packet.
• If the datagram arrived on the interface specified in the routing table for the source address; then the RPF check succeeds.
• Otherwise, the RPF Check fails.
Reverse Path Forwarding (RPF)
18© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast Routing – High LevelMulticast Routing – High Level
Source151.10.3.21
Example: RPF Checking RPF Checking
Mcast Packets
RPF Check FailsRPF Check Fails Packet arrived on wrong interface!Packet arrived on wrong interface!
19© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast Routing – High LevelMulticast Routing – High Level
RPF Check Fails!
Unicast Route TableUnicast Route Table
NetworkNetwork Interface Interface
151.10.0.0/16151.10.0.0/16 S1S1
198.14.32.0/24198.14.32.0/24 S0S0
204.1.16.0/24204.1.16.0/24 E0E0
A closer look: RPF Check Fails RPF Check Fails
Packet Arrived on Wrong Interface!
E0
S1
S0
S2
S1S1
Multicast Packet fromSource 151.10.3.21
XDiscard Packet!
20© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast Routing – High LevelMulticast Routing – High Level
A closer look: RPF Check SucceedsRPF Check Succeeds
RPF Check Succeeds!
Unicast Route TableUnicast Route Table
NetworkNetwork Interface Interface
151.10.0.0/16151.10.0.0/16 S1S1
198.14.32.0/24198.14.32.0/24 S0S0
204.1.16.0/24204.1.16.0/24 E0E0
E0
S1
S0
S2
Multicast Packet fromSource 151.10.3.21
Packet Arrived on Correct Interface!S1S1
Forward out all outgoing interfaces.(i. e. down the distribution tree)
21© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast Routing – High LevelMulticast Routing – High Level
Why do RPF Checks?
E0
S1
S0
S2
• Avoid receiving duplicate packets
• Happens with PIM-DM flooding
• Avoid loops
• Ensures fan-out from source
•multicasting forwarding AWAY from the source
• RPF interface always leads back to the source Non-RPF Interface
RPF Interface
22© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast Routing – High LevelMulticast Routing – High Level
•Dense-mode• Uses “Push” Model
• Traffic Flooded throughout network
• Pruned back where it is unwanted
• Flood & Prune behavior (typically every 3 minutes)
• Sparse-mode
• Uses “Pull” Model
• Traffic sent only to where it is requested
• Explicit Join behavior
23© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast Routing – High LevelMulticast Routing – High Level
• Currently, there are four multicast routing protocols:
– PIM-Dense Mode (Internet-draft)
– PIM-Sparse Mode (RFC 2362- v2)
– PIM-Source Specific Multicast
– Bidirectional PIM
– Others (DVMRP, MOSPF, etc.)
• What “Protocol Independent” means
– Doesn’t care how the unicast routing table has been
built• DVMRP cares – it builds its own !!
24© 2002, Cisco Systems, Inc. IP Multicast Basics
Source
Initial Flooding
Receiver
Multicast Packets
(S, G) State created inevery every router in the network!
PIM-DM Flood and PrunePIM-DM Flood and Prune
25© 2002, Cisco Systems, Inc. IP Multicast Basics
Source
Pruning Unwanted Traffic
Receiver
Multicast Packets
Prune Messages
PIM-DM Flood and PrunePIM-DM Flood and Prune
26© 2002, Cisco Systems, Inc. IP Multicast Basics
Results After Pruning
Source
Receiver
Multicast Packets
Flood and Prune processFlood and Prune processrepeats every 3 minutes!!!repeats every 3 minutes!!!
(S, G) State still exists inevery every router in the network!
PIM-DM Flood and PrunePIM-DM Flood and Prune
27© 2002, Cisco Systems, Inc. IP Multicast Basics
PIM-DM — EvaluationPIM-DM — Evaluation
• Most effective for small pilot networks• Advantages:
– Easy to configure—two commands– Simple flood and prune mechanism
• Potential issues...– Inefficient flood and prune behavior– Complex Assert mechanism
– Mixed control and data planes
•Results in (S, G) state in every router in the network
•Can result in non-deterministic topological
behaviors– No support for shared trees
28© 2002, Cisco Systems, Inc. IP Multicast Basics
PIM-SM (RFC 2362)PIM-SM (RFC 2362)
• Supports both source and shared trees– Assumes no hosts want multicast traffic unless they
specifically ask for it – PULL MODEL
• Uses a Rendezvous Point (RP)– Senders and Receivers “rendezvous” at this point to learn of
each others existence.
• Senders are “registered” with RP by their first-hop router.
• Receivers are “joined” to the Shared Tree (rooted at the RP) by their local Designated Router (DR).
• Appropriate for…– Wide scale deployment for both densely and sparsely
populated groups in the enterprise– Optimal choice for all production networks regardless of size
and membership density.
29© 2002, Cisco Systems, Inc. IP Multicast Basics
PIM-SM Shared Tree JoinPIM-SM Shared Tree Join
Receiver
RP
(*, G) Join
Shared Tree
(*, G) State created onlyalong the Shared Tree.
Router knows IP address of RPIf the last of the receivers behind thisrouter leaves, then its (*.G) OIL is empty (NULL). The router will send (*,G) Prune towards RP.
30© 2002, Cisco Systems, Inc. IP Multicast Basics
PIM-SM Sender RegistrationPIM-SM Sender Registration
Receiver
RP
(S, G) Join
Source
Shared Tree
(S, G) Register (unicast)
Source Tree
2. (S, G) State created onlyalong the Source Tree.
3. Source requests RP to build a tree to it1. Source sends multicast data
encapsulated in PIM-SM (S,G) Register to RP - unicast
4. RP sends packet on shared tree
5. RP sends (S,G) Jointowards Source
6. RP now has an SPT to the source
7. RP sends a (S,G) Register-Stop towards Source
8. Traffic flows SPT to RP and Shared Tree to Receiver
31© 2002, Cisco Systems, Inc. IP Multicast Basics
PIM-SM SPT SwitchoverPIM-SM SPT Switchover
Receiver
RP
(S, G) Join
Source
Source Tree
Shared Tree1. Last-hop router joins the Source Tree.
2. Additional (S, G) State is created along new part of the Source Tree.
Traffic Flow
3. Router is receiving duplicate packets – SPT and Shared TreeRouter send (S,G) RP-bit Prune toward RP
(S,G) RP-bit Prune
(S,G) Prune4. RP sends (S.G) Prune towards Source
32© 2002, Cisco Systems, Inc. IP Multicast Basics
PIM-SM State RefreshPIM-SM State Refresh
Receiver
RP
(*, G) State created onlyalong the Shared Tree.
Receiver
RTR Y sends (*,G) and (S,G) Joins to RTR X every 1 minute
RTR X
RTR Y
RTR X waits for 3 minute Before flushing the interface from the (S,G) or (*,G) OIL
Source
33© 2002, Cisco Systems, Inc. IP Multicast Basics
PIM-SM—EvaluationPIM-SM—Evaluation
•Effective for sparse or dense distribution of multicast receivers
•Advantages:
– Traffic only sent down “joined” branches
– Can switch to optimal source-trees for high traffic
sources dynamically
– Unicast routing protocol-independent
34© 2002, Cisco Systems, Inc. IP Multicast Basics
PIM SSMPIM SSM
• Assume a One-to-Many Multicast Model.– Example: Video/Audio broadcasts, Stock Market data
• Why does PIM-SM need a Shared Tree?– So that hosts and 1st hop routers can learn who the active
source is for the group.
• What if this was already known?– Hosts could use IGMPv3 to signal exactlyexactly which (S,G) SPT
to join.
– The Shared Tree & RP wouldn’t be necessary.
– Different sources could share the same Group address and not interfere with each other.
• Result: Source Specific Multicast (SSM)
35© 2002, Cisco Systems, Inc. IP Multicast Basics
PIM SSMPIM SSM
•SSM Advantages
– Allows immediate use of shortest forwarding
path to a specific source, without need to
create shared tree.
– Eliminates dependence on MSDP for finding
sources.
– Simplifies address allocation for global, single
source groups when combined with
elimination of shared trees.
36© 2002, Cisco Systems, Inc. IP Multicast Basics
Receiver 1
Source
Out-of-band Source DirectoryExample: Web Server
Receiver learns of source, group/port
IGMPv3 (S, G) Join
Receiver sends IGMPv3 (S,G) Join
(S, G) Join
First-hop send PIM s,g join directly toward Source
BA C D
FD
PIM Source Specific ModePIM Source Specific Mode
37© 2002, Cisco Systems, Inc. IP Multicast Basics
PIM Source Specific ModePIM Source Specific Mode
Receiver 1
B
F
A C D
Source
E
Result: Shortest Path Tree rootedat the Source, with NO Shared Tree.
38© 2002, Cisco Systems, Inc. IP Multicast Basics
Rendezvous Point – High LevelRendezvous Point – High Level
• RP is key to the operation of PIM-SM• How do the multicast routers know about the RP?• Three methods are popular
– Static RP• Statically configure the RP address on all multicast routers
• Can have a separate RPs for different groups
– Auto-RP• Routers that want to be RPs announce to Mapping Agents
• Mapping Agents determine RP and inform all routers
• Uses dense mode groups 224.0.1.39 and 224.0.1.40 to achieve this
– BSR• Similar to Auto-RP – Candidate RPs announce their intention
• But Candidate BSRs don’t determine the RPs – they send all the RP
information to all routers and let them decide.
39© 2002, Cisco Systems, Inc. IP Multicast Basics
AgendaAgenda
• Part 1 - Basic IP Multicast– Multicast Applications, Network Components,
Addressing, IGMP
– Multicast Routing at a High Level
• Part 2 - Configuration Example
• Part 3 – RP Details– Auto-RP, BSR, Anycast
40© 2002, Cisco Systems, Inc. IP Multicast Basics
Configuration SetupConfiguration Setup
R1
R6
10.0.1/24
192.168.1/3010.0.2/24
PE and P L0 = 12.0.0.N / 32
R9(PE)
1.1.1.1/32
R7
R8-RR
R3 - RR
R2(PE)
R5R4(PE)
s3/0
s2/0
s3/0
s2/0
s2/0
s2/0
e0/0
e0/0
e0/0e1/0
e0/0
s1/0
s1/0
s1/0
e0/0
s4/0
s3/0
s3/0
s3/0
s2/0s1/0
s4/0s2/0
s1/0
5.5.5.5/32
10.0.3/2410.0.4/24
10.0.5/24
10.0.6/2410.0.7/24
10.0.8/24
10.0.9/24
192.168.3/30
192.168.2/30
AS 13979
ip igmp join-group 239.1.1.1
Multiple Loops
pinging 239.1.1.1
41© 2002, Cisco Systems, Inc. IP Multicast Basics
Config and Show Commands - 1Config and Show Commands - 1
• All interfaces on PE and P routers are enabled for PIM. For instance, interface Serial1/0 ip address 10.0.1.2 255.255.255.0 ip pim sparse-dense-mode
– including loopback0
• What interfaces are enabled for PIM?– R2#sh ip pim int
Address Interface Ver/ Nbr Query DR DR Mode Count Intvl Prior12.0.0.2 Loopback0 v2/SD 0 30 1 12.0.0.210.0.1.2 Serial1/0 v2/SD 1 30 1 0.0.0.010.0.2.2 Serial2/0 v2/SD 1 30 1 0.0.0.010.7.0.2 Serial4/0 v2/SD 0 30 1 0.0.0.0
42© 2002, Cisco Systems, Inc. IP Multicast Basics
Config and Show Commands - 2Config and Show Commands - 2
• To check PIM on the customer interface
– R2#sh ip pim vrf test1 intAddress Interface Ver/ Nbr Query DR DR Mode Count Intvl Prior
192.168.1.2 Ethernet0/0 v2/SD 1 30 1 192.168.1.2
12.0.0.2 Tunnel0 v2/SD 2 30 1 12.0.0.9
R2#
• To check PIM adjacencyR2#sh ip pim neiPIM Neighbor Table
Neighbor Interface Uptime/Expires Ver DR
Address Priority/Mode
10.0.1.7 Serial1/0 00:26:45/00:01:38 v2 1 /
10.0.2.3 Serial2/0 00:26:45/00:01:43 v2 1 /
R2#~
43© 2002, Cisco Systems, Inc. IP Multicast Basics
Config and Show Commands - 3Config and Show Commands - 3
• To check PIM adjacency on the customer interfaceR2#sh ip pim vrf test1 neiPIM Neighbor TableNeighbor Interface Uptime/Expires Ver DRAddress Priority/Mode192.168.1.1 Ethernet0/0 00:28:37/00:01:42 v2 1 /12.0.0.9 Tunnel0 00:25:27/00:01:24 v2 1 / DR12.0.0.4 Tunnel0 00:28:26/00:01:29 v2 1 /R2#
• Check what is the RP for this groupR2#sh ip pim rp mapPIM Group-to-RP MappingsGroup(s): 224.0.0.0/4, Static RP: 12.0.0.3 (?)R2#
• For customer facing, R2#sh ip pim vrf test1 rp mapPIM Group-to-RP MappingsGroup(s): 224.0.0.0/4, Static RP: 5.5.5.5 (?)R2#
44© 2002, Cisco Systems, Inc. IP Multicast Basics
Config and Show Commands - 4Config and Show Commands - 4
• Is the AT&T RP reachable?R2#ping 12.0.0.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 12.0.0.3, timeout is 2 seconds:
!!!!!
• Is the customer RP reachable?R2#ping vrf test1 5.5.5.5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2
seconds:
!!!!!
45© 2002, Cisco Systems, Inc. IP Multicast Basics
Config and Show Commands - 5Config and Show Commands - 5
• Let’s make R2 a receiverR2(config)#int loop0R2(config-if)#ip igmp join-group 239.2.2.2R2#sh ip igmp gIGMP Connected Group MembershipGroup Address Interface Uptime Expires Last Reporter239.1.1.1 Loopback0 02:21:17 stopped 0.0.0.0239.2.2.2 Loopback0 00:01:43 00:02:12 12.0.0.2224.0.1.40 Loopback0 02:21:18 00:02:06 12.0.0.2
• R2 sends *G Join to RP (R3)R2#sh ip mro 239.2.2.2(*, 239.2.2.2), 00:03:50/00:02:08, RP 12.0.0.3, flags: SJCL Incoming interface: Serial2/0, RPF nbr 10.0.2.3 Outgoing interface list: Loopback0, Forward/Sparse-Dense, 00:03:50/00:02:08
• What does the RP (R3) think about 239.2.2.2?R3#sh ip mro 239.2.2.2 (*, 239.2.2.2), 00:14:12/00:02:35, RP 12.0.0.3, flags: S Incoming interface: Null, RPF nbr 0.0.0.0 Outgoing interface list: Serial1/0, Forward/Sparse-Dense, 00:14:12/00:02:35
46© 2002, Cisco Systems, Inc. IP Multicast Basics
Config and Show Commands - 6Config and Show Commands - 6
• Let’s have a source behind R4 send to 239.2.2.2R4#ping 239.2.2.2
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 239.2.2.2, timeout is 2 seconds:
Reply to request 0 from 10.0.2.2, 48 ms
Reply to request 0 from 10.0.2.2, 100 ms
Reply to request 0 from 10.0.2.2, 100 ms
R4#
• Why three responses?
– ping to multicast sends pings on all interfaces
– can control this via extended ping
– response to ping is unicast
• What states do the routers show?
47© 2002, Cisco Systems, Inc. IP Multicast Basics
Config and Show Commands - 7Config and Show Commands - 7
• Look at the state on R4 – first hop router
(*, 239.2.2.2), 00:03:41/stopped, RP 12.0.0.3, flags: SPF
Incoming interface: Serial4/0, RPF nbr 10.0.4.7
Outgoing interface list: Null
(10.0.6.4, 239.2.2.2), 00:03:41/00:00:26, flags: FT
Incoming interface: Serial3/0, RPF nbr 0.0.0.0, Registering
Outgoing interface list:
Serial4/0, Forward/Sparse-Dense, 00:03:41/00:03:24
(12.0.0.4, 239.2.2.2), 00:03:41/00:00:32, flags: FT
Incoming interface: Loopback0, RPF nbr 0.0.0.0, Registering
Outgoing interface list:
Serial4/0, Forward/Sparse-Dense, 00:03:41/00:03:24
48© 2002, Cisco Systems, Inc. IP Multicast Basics
Multicast TraceMulticast Trace
R1#mtrace 1.1.1.1 5.5.5.5 ? Hostname or A.B.C.D Group to trace route via <cr>
R1#mtrace 1.1.1.1 5.5.5.5 Type escape sequence to abort.Mtrace from 1.1.1.1 to 5.5.5.5 via RPFFrom source (?) to destination (?)Querying full reverse path... 0 5.5.5.5-1 192.168.3.5 PIM [1.1.1.1/32]-2 0.0.0.0 None Admin. Prohibited !RPF!192.168.3.4 [default]-3 0.0.0.0 PIM [1.1.1.1/32]-4 192.168.1.1 PIM [1.1.1.1/32]R1#
49© 2002, Cisco Systems, Inc. IP Multicast Basics
AgendaAgenda
• Part 1 - Basic IP Multicast– Multicast Applications, Network Components,
Addressing, IGMP
– Multicast Routing at a High Level
• Part 2 - Configuration Example
• Part 3 – RP Details– Auto-RP, BSR, Anycast
50© 2002, Cisco Systems, Inc. IP Multicast Basics
Rendezvous Points (RPs)Rendezvous Points (RPs)
• Meeting Place for Source and Receivers
• Last hop routers join the RP
• First hop routers register towards RP– Designated routers send Register Messages towards RP
• RPs can be– Manually configured - Static RPs
– Dynamic via Cisco’s Auto-RP
– Dynamic via BSR
• One RP can support several groups
• A single group cannot have more than one active RP
• If RP is not known, group will become dense
51© 2002, Cisco Systems, Inc. IP Multicast Basics
Static RP’sStatic RP’s
• Hard-coded RP address
– When used, must be configured on every router
– All routers must have the same RP address
– RP fail-over not possible (except if Anycast RPs are used)
• Commandip pim rp-address <address> [group-list <acl>] [override]
– Optional group list specifies group range
• Which multicast groups should this RP be used for?
• Default is all – 224.0.0.0/4
– Override keyword “overrides” Auto-RP information
• w/o override - Auto-RP learned info takes precedence
52© 2002, Cisco Systems, Inc. IP Multicast Basics
Auto-RP OverviewAuto-RP Overview
• A way to let routers in a PIM domain dynamically learn about active RPs
• Basic Idea– Routers wishing to be RPs for a group(s) multicast a
Candidate RP message
• To group address 224.0.1.39 (Cisco-RP-Announce)
– A Mapping Agent (MA) gets these and selects one
– MA multicasts this RP info to all other routers
• To group address 224.0.1.40 (Cisco-RP-Discovery)
– Routers cache this Group-to-RP mapping
– 224.0.1.39 and 224.0.1.40 operate in dense mode
53© 2002, Cisco Systems, Inc. IP Multicast Basics
Auto-RP—From 10,000 FeetAuto-RP—From 10,000 Feet
Announce Announce
An
no
un
ceA
nn
ou
nce
Announce Announce
An
no
un
ceA
nn
ou
nce
Announce
RP-Announcements multicast to theCisco Announce (224.0.1.39) group
AA
CC DDC-RP
1.1.1.1C-RP
2.2.2.2
BB
MA MA
54© 2002, Cisco Systems, Inc. IP Multicast Basics
CC DDC-RP
1.1.1.1C-RP
2.2.2.2
Auto-RP—From 10,000 FeetAuto-RP—From 10,000 Feet
Discovery
RP-Discoveries multicast to theCisco Discovery (224.0.1.40) group
MA MADiscovery
Discovery
Dis
cove
ry
Dis
cove
ry
AA
Discovery
Discovery
Dis
cove
ry
Dis
cove
ry
BB
55© 2002, Cisco Systems, Inc. IP Multicast Basics
Redundancy via Auto-RPRedundancy via Auto-RP
• Mapping Agent selects an RP with the highest IP address
• More than one candidate RP is announced for a group– If primary fails, then the candidate with next highest
IP address becomes the RP for that group
56© 2002, Cisco Systems, Inc. IP Multicast Basics
Sparse-Dense ModeSparse-Dense Mode
• Problem – Chicken & Egg– Mapping agent sends RP announcements to group 224.0.1.40
– Routers need to send joins to Auto-RP group 224.0.1.10 to receive this announcement
– They have to send *G Join to the RP
– But they need to know the RP to be able to that
• Same issue applies to C-RP announcements• Solution – sparse-dense
– Configure interfaces to be sparse-dense
– If RP is known, interface uses sparse-mode
– If RP is not known, interface uses dense mode
• This allows Auto-RP groups to run in dense mode and all other groups in sparse-mode
57© 2002, Cisco Systems, Inc. IP Multicast Basics
Auto-RP ConfigurationAuto-RP Configuration
• ip pim send-rp-discovery loopback0 scope 16– Makes this router a mapping agent
– Need to configure pim in the loopback interface
• ip pim send-rp-announce loopback0 scope 16 – Makes this router a Candidate RP
– Scope is a TTL value
• You can specify an ACL with send-rp-announce• ACL specifies group range for which this router is C-
RP
58© 2002, Cisco Systems, Inc. IP Multicast Basics
BSR OverviewBSR Overview
• A single Bootstrap Router (BSR) is elected– Multiple Candidate BSR’s (C-BSR) can be configured
• Provides backup in case currently elected BSR fails
– C-RP’s send C-RP announcements to the BSR
• C-RP announcements are sent via unicast
• BSR stores ALL C-RP announcements in the “RP-set”
– BSR periodically sends BSR messages to all routers
• BSR Messages contain entire RP-set and IP address of BSR
• Messages are flooded hop-by-hop throughout the network away from the BSR
– All routers select the RP from the RP-set
• All routers use the same selection algorithm; select same RP
59© 2002, Cisco Systems, Inc. IP Multicast Basics
PIMv2 Sparse Mode
PIMv2 Sparse Mode
C-RP C-RP
D
E
F
G
A
BSR—From 10,000 feetBSR—From 10,000 feet
C-RP A
dvertisement
(unicast)
C-RP Advertisement
(unicast)
B C
BSRBSR
60© 2002, Cisco Systems, Inc. IP Multicast Basics
PIMv2 Sparse Mode
PIMv2 Sparse Mode
C-RP C-RP
D
E
F
G
A
BSR—From 10,000 feetBSR—From 10,000 feet
BS
R M
sg
s
BSR MsgsBSR Msgs
BS
R M
sg
s
BSR Msgs Flooded Hop-by-Hop
B C
BSRBSR
61© 2002, Cisco Systems, Inc. IP Multicast Basics
MSDP ConceptMSDP Concept
•Simple but elegant
– Utilize inter-domain source trees
– Reduces problem to locating
active sources
– RP or receiver last-hop can join
inter-domain source tree
62© 2002, Cisco Systems, Inc. IP Multicast Basics
MSDP ConceptsMSDP Concepts
•Works with PIM-SM only– RP’s knows about all sources in a domain
•Sources cause a “PIM Register” to the RP
•Can tell RP’s in other domains of its sources– Via MSDP SA (Source Active) messages
– RP’s know about receivers in a domain•Receivers cause a “(*, G) Join” to the RP
•RP can join the source tree in the peer domain– Via normal PIM (S, G) joins
63© 2002, Cisco Systems, Inc. IP Multicast Basics
Domain C
Domain B
Domain D
Domain E
SA
SA
SA SA
SA
SA
Source ActiveMessages
SA
Domain A
SA Message192.1.1.1, 224.2.2.2
SA Message192.1.1.1, 224.2.2.2
r
MSDP Peers
RP
RP
RP
RP
MSDP OverviewMSDP Overview
Join (*, 224.2.2.2)
sRP
Register192.1.1.1, 224.2.2.2
MSDP Example
64© 2002, Cisco Systems, Inc. IP Multicast Basics
Domain C
Domain B
Domain D
Domain E
Domain A
RP
RP
RP
RP
r
MSDP Peers
Join
(S
, 224
.2.2
.2)
RP
MSDP OverviewMSDP Overview
s
MSDP Example
65© 2002, Cisco Systems, Inc. IP Multicast Basics
Domain C
Domain B
Domain D
Domain E
Domain A
RP
RP
RP
RP
r
MSDP Peers
Multicast Traffic RP
MSDP OverviewMSDP Overview
s
MSDP Example
66© 2002, Cisco Systems, Inc. IP Multicast Basics
Domain C
Domain B
Domain D
Domain E
Domain A
RP
RP
RP
RP
r
MSDP Peers
Multicast Traffic RP
MSDP OverviewMSDP Overview
s
Join
(S, 224.2.2.2)
MSDP Example
67© 2002, Cisco Systems, Inc. IP Multicast Basics
Domain C
Domain B
Domain D
Domain E
Domain A
RP
RP
RP
RP
r
MSDP Peers
Multicast Traffic RP
MSDP OverviewMSDP Overview
s
MSDP Example
68© 2002, Cisco Systems, Inc. IP Multicast Basics
Anycast RP – OverviewAnycast RP – Overview
•Uses single statically defined RP address– Two or more routers have same RP address
• RP address defined as a Loopback Interface.• Loopback address advertised as a Host route.
– Senders & Receivers Join/Register with closest RP• Closest RP determined from the unicast routing table.
– Can never never fall back to Dense mode.• Because RP is statically defined.
•MSDP session(s) run between all RPs– Informs RPs of sources in other parts of network– RPs join SPT to active sources as necessary
69© 2002, Cisco Systems, Inc. IP Multicast Basics
Anycast RP – OverviewAnycast RP – Overview
MSDPMSDP
RecRecRecRec RecRecRecRec
SrcSrc SrcSrc
SA SAAA
RP1
10.1.1.1BB
RP2
10.1.1.1
XX
70© 2002, Cisco Systems, Inc. IP Multicast Basics
Anycast RP – OverviewAnycast RP – Overview
RecRecRecRec RecRecRecRec
SrcSrcSrcSrc
AA
RP1
10.1.1.1BB
RP2
10.1.1.1
XX
71© 2002, Cisco Systems, Inc. IP Multicast Basics
Anycast RP ConfigurationAnycast RP Configuration
ip pim rp-address 10.1.1.1 ip pim rp-address 10.1.1.1
Interface loopback 0 ip address 10.0.0.2 255.255.255.255
Interface loopback 1 ip address 10.1.1.1 255.255.255.255!ip msdp peer 10.0.0.1 connect-source loopback 0ip msdp originator-id loopback 0
Interface loopback 0 ip address 10.0.0.1 255.255.255.255
Interface loopback 1 ip address 10.1.1.1 255.255.255.255!ip msdp peer 10.0.0.2 connect-source loopback 0ip msdp originator-id loopback 0
MSDPMSDPBB
RP2
AA
RP1
XX YY
72© 2002, Cisco Systems, Inc. IP Multicast Basics
• White Papers
• Web and Mailers
• Cisco Press
CCO Multicast page:http://www.cisco.com/go/ipmulticast
Questions:[email protected]
Customer Support Mailing List: [email protected]
More InformationMore Information
RTFB = “Read the Fine Book”