multicast troubleshooting
TRANSCRIPT
IBRKIPM-2264
Multicast Troubleshooting
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Housekeeping
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Housekeeping Items
Maintaining a Multicast Network
Quick Review
Troubleshooting Multicast
Agenda
3
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Housekeeping
Cell Phones
“Intermediate” Class
-Assumes Multicast Operational Experience
Slide Format
4
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Housekeeping
New Case to Solve Case Closed One slide Case
Geek - o - meter Geek-o-meter*
* Mr Multicast himself, Beau Williamson
5
Maintaining a Multicast Network
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Maintaining a Multicast Network Challenges
Multicast forwarding state is dynamic
Best Effort Delivery
No Congestion control
-Requires External Monitoring
-Applications may have feedback mechanism (e.g. Tibco, PGM)
“High” on the network food chain
7
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Router
Cards
Interfaces
Routing
Packet
Maintaining a Multicast Network Challenges
Multicast Infrastructure Overlay
Supporting Multicast Configs
PIM Neighbors
Multicast Distribution Trees
Knowledge of RP (root of shared tree)
Knowledge of Source (root of source tree)
Quick Review
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Quick Review PIM-SM Categories
Any Source Multicast (ASM)
-Original (Classic) PIM-SM
-Supports both Shared and Source Trees
Source Specific Multicast (SSM)
-a.k.a. Single Source Multicast
-Supports only Source Trees
No need for RPs, RP Failover, etc.
Bidirectional PIM (Bidir)
-Supports only Shared Trees
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PIM SM
RPF
Source Tree
{S,G}
Quick Review Frequently Used Terms
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Quick Review Frequently Used Terms
RP - Rendezvous Point
MDT - Multicast Distribution Tree
FHR - First Hop Router
LHR - Last Hop Router
IR - Intermediate Router
IGMP - Internet Group Management Protocol http://en.wikipedia.org/wiki/Internet_Group_Management_Protocol
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Quick Review Frequently Used Terms
(*,G) = *,G
= Shared Tree
= RP tree
(S,G) = S,G
= Source Tree
= Shortest Path Tree
Q: What is the Root of the (*,G) Tree?
Q: What is the Root of the (S,G) Tree?
A: RP
A: Source
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Quick Review Frequently Used Terms
IIF = Incoming Interface
OIL = Outgoing interface List
Q: What does the IIF of the (*,G) Tree point towards?
Q: What does the IIF of the (S,G) Tree point towards
A: RP
A: Source
Interface towards the
root of the tree
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Quick Review Sending a Join
Assuming Router A
• Knows the RP
• Has the RP in its RIB via an IGP with B
• Has a PIM neighbor with Router B
IP of the RP? 224.0.0.13?
(All PIM Routers) IP of Router B
(10.4.5.4)
10.4.5.0 .5 .4
PIM Join
A B RP
Q: When Router A sends a PIM (*,G) Join out, what will be the Destination IP?
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Message Type Destination
0 = Hello Multicast to ALL-PIM-ROUTERS
1 = Register Unicast to RP
2 = Register-Stop Unicast to source of Register packet
3 = Join/Prune Multicast to ALL-PIM-ROUTERS
4 = Bootstrap Multicast to ALL-PIM-ROUTERS
5 = Assert Multicast to ALL-PIM-ROUTERS
The PIM header common to all PIM messages is:
PIM Ver
PIM Version number is 2.
Some PIM Types are:
Quick Review Sending a Join
http://www.ietf.org/rfc/rfc4601.txt
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Quick Review Sending a Join
10.4.5.0 .5 .4
PIM Join
A B RP
DIP 224.0.0.13
Q: When Router A sends a PIM (*,G) Join out, what will be the Destination IP?
IP of the RP? 224.0.0.13?
(All PIM Routers) IP of Router B
(10.4.5.4)
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Quick Review Sending a Join
10.4.5.0 .5 .4
A B
RP
C
.1
PIM Join DIP 224.0.0.13
Q: If the destination IP address of the Join is 224.0.0.13 (all PIM Routers), then
how do we keep Router B and Router C from BOTH acting on that join?
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Quick Review Sending a Join
The address of upstream neighbor that is the
target of the message
10.4.5.0 .5 .4
A B
RP
C
.1
http://www.ietf.org/rfc/rfc4601.txt
PIM Join DIP 224.0.0.13
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Quick Review: Sending a Join
Destination IP
224.0.0.13
RP
2.2.2.2
IP address of B
10.4.5.4
10.4.5.0 .5 .4
A B
RP
C
.1
http://www.ietf.org/rfc/rfc4601.txt
PIM Join DIP 224.0.0.13
Geek - o - meter
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FHR
Quick Review Registering a Source***
RP = 2.2.2.2
E0
Register Stop to the FHR
Mcast data Mcast packets now only out the (S,G)
tree
Mcast data
Mcast Data
Mcast packet is encapsulated into unicast
PIM packet:
Destination IP is the RP.
PIM header type is Register Mcast data Dest IP=RP
RP sends PIM (S,G) Join Back Towards Source
if there is an active shared tree for that G
E0 added to the OIL
for (S,G)
Mcast packets now get sent out
twice
1.With Register
2.Out (S,G)
Mcast data
Mcast data Once the RP sees the packets come in
on the (S,G), it sends a unicast Register
Stop
***When a shared MDT is already
active for that group on the RP
Geek - o - meter
PIM
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Designated Router (DR):
A shared-media LAN like Ethernet may have multiple PIM-SM
routers connected to it. A single one of these routers, the
DR, will act on behalf of directly connected hosts with respect
to the PIM-SM protocol. A single DR is elected per interface
(LAN or otherwise) using a simple election process.
What IS a Designated Router?
RE: “Election” of DR ---
Default behavior is for highest IP address on the
LAN to become the DR unless the DR priority
option is configured
Vlan 110 .3
.2
RP
Quick Review: Designated Routers (DRs)
http://www.ietf.org/rfc/rfc4601.txt
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Quick Review: Designated Routers (DRs)
The DR_Priority Option allows a network administrator to give
preference to a particular router in the DR election process by
giving it a numerically larger DR Priority. …. The default priority is 1
What the DR Priority Option?
R4(config-if)# ip pim dr-priority ?
<0-4294967294> DR priority, preference given to larger value
http://www.ietf.org/rfc/rfc4601.txt
Vlan 110 .3
.2
RP
Troubleshooting Multicast
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Troubleshooting Multicast
Troubleshooting Backwards With Multicast
Topologies Overview
ASM Troubleshooting
SSM Specific Troubleshooting
“In solving a problem of this sort, the grand thing is to be able to reason backward. That is a very useful accomplishment, and a very easy one, but people do not practice it much.”
Sherlock Holmes
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Multicast – Troubleshooting ASM
Traffic
Troubleshooting
RP FHR
LHR
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Multicast – Troubleshooting SSM
Traffic
Troubleshooting
FHR
LHR
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Topologies Overview
10.1.2.0
10.2.3.0
10.2.4.0 10.4.5.0
3/1 0/1
0/2
0/3
3/3
2/2 2/4
3/5
3/4
3/5
6500-1 L0: 1.1.1.1
CRS L0: 2.2.2.2
N7K L0: 3.3.3.3
6500-2 L0: 4.4.4.4
4900M L0: 5.5.5.5
10.3.5.0
R1 R2
R3
R4
R5
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R1 R2
R3
R4
R5
Topologies Overview
Source(s)
Receiver(s)
Reference Router
ASM Troubleshooting
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ASM Troubleshooting
R1 R2
R3
R4
(*,G) from LHR towards the RP 1
LHR Cutting over to SPT (S,G)
3
RP FHR
LHR
FHR registers source with RP
RP sends PIM (S,G) Join Towards Source
2
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ASM Troubleshooting: Shared Tree
(*,G) from LHR towards the RP 1
RP
R2
R3
R4
LHR receives
IGMP Membership Report
1a
LHR (R5) sends a PIM (*,G)
To R4
1b
R4 (an IR) sends a PIM (*,G)
To R2 (RP)
1c
LHR
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ASM Troubleshooting: Shared Tree
R2
R3
R4
LHR receives
IGMP Membership Report
1a
LHR
LHR receives
IGMP Membership Report
1a
RP
LHR Receives IGMP Membership Report 1a
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LHR#show ip mroute Is completely empty
LHR#show ip igmp group Is completely empty
LHR#show ip igmp interface Is completely empty
LHR#show ip interface gig1/1 No multicast reserved groups joined
ASM Troubleshooting: Shared Tree
LHR Receives
IGMP Membership Report
1a
Problem:
LHR not seeing an IGMP Membership
Report from Receiver
LHR Receives IGMP Membership Report 1a
R3
R4
R2
RP
Receiver:
100.1.1.100
1/1
LHR
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LHR#show run interface gig1/1 interface GigabitEthernet1/1
no switchport
ip address 100.1.1.1 255.255.255.0
ip pim sparse-mode
ASM Troubleshooting: Shared Tree
LHR Receives
IGMP Membership Report
1a
Problem:
LHR not seeing an IGMP Membership
Report from Receiver
Issue:
PIM not enabled on interface of
Receiver
Other Things to Look For:
Layer 1 issues, Layer 2 issues, Access-lists.
R3
R4
R2
RP
Receiver:
100.1.1.100
LHR
LHR Receives IGMP Membership Report 1a
1/1
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ASM Troubleshooting: Shared Tree
Receiver:
100.1.1.100
LHR Receives
IGMP Membership Report
1a
GigabitEthernet1/1 is up, line protocol is up
Internet address is 100.1.1.1/24
….
Directed broadcast forwarding is disabled
Multicast reserved groups joined: 224.0.0.1 224.0.0.2 224.0.0.22 224.0.0.13
R3
R4
R2
RP
Receiver:
100.1.1.100
LHR
LHR Receives IGMP Membership Report 1a
LHR#show ip interface gig1/1
1/1
Note Difference
Before enabling pim sparse-mode on the
interface, the result of show ip interface
gig1/1 resulted in showing that no multicast
reserved groups were joined.
Now…
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ASM Troubleshooting: Shared Tree
http://www.iana.org/assignments/multicast-addresses/multicast-addresses.xml#multicast-addresses-1
Address(s) Description
224.0.0.0 Base Address
224.0.0.1 All Systems on this Subnet
224.0.0.2 All Routers on this Subnet
….
224.0.0.4 DVMRP Routers [RFC1075]
224.0.0.5 OSPFIGP All Routers [RFC2328]
224.0.0.6 OSPFIGP Designated Routers [RFC2328]
….
224.0.0.9 RIP2 Routers [RFC1723]
224.0.0.10 IGRP Routers
….
224.0.0.13 All PIM Routers
….
224.0.0.18 VRRP
…
224.0.0.22 IGMP
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LHR#show run interface gig1/1 interface GigabitEthernet1/1
no switchport
ip address 100.1.1.1 255.255.255.0
ip pim sparse-mode
ASM Troubleshooting: Shared Tree
LHR receives
IGMP Membership Report
1a
LHR#show ip igmp groups
IGMP Connected Group Membership
Group Address Interface Uptime Expires Last Reporter
239.1.1.1 GigabitEthernet1/1 00:18:35 00:02:31 100.1.1.100
R3
R4
R2
RP
Receiver:
100.1.1.100
1/1
LHR
LHR Receives IGMP Membership Report 1a
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ASM Troubleshooting: Shared Tree
10.4.5.0
10.3.5.0
R2
R3
R4 LHR (R5) sends a PIM (*,G)
To R4
1b
LHR RP
Who?
Where?
RPF Nbr?
LHR (R5) sends a PIM (*,G)
To R4
1b
RP
LHR Sends PIM (*,G) Join 1b
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LHR#show ip mroute (*, 239.1.1.1), 00:01:23/00:02:48, RP 0.0.0.0, flags: SJC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/1, Forward/Sparse, 00:01:23/00:02:48, H
LHR#show ip pim rp 239.1.1.1 Group: 239.1.1.1, RP: 0.0.0.0
ASM Troubleshooting: Shared Tree
Problem:
LHR doesn‘t know who the RP is for
this group.
RP
Who?
Where?
RPF Nbr?
?
?
LHR Sends PIM (*,G) Join 1b
RP 10.4.5.0
2/4
3/5
1/4
1/5
10.3.5.0
R2
R3
1/1
R4
LHR
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LHR(config)#ip pim rp-address 2.2.2.2 ?
<1-99> Access-list reference for group
<1300-1999> Access-list reference for group (expanded range)
WORD IP Named Standard Access list
override Overrides dynamically learnt RP mappings
<cr>
LHR(config)#ip pim rp-address 2.2.2.2 override
ASM Troubleshooting: Shared Tree
• Static
• Auto-rp
• BSR
Note:
RP information can be shared 3 ways
RP
Who?
Where?
RPF Nbr?
LHR Sends PIM (*,G) Join 1b
RP
2.2.2.2
10.4.5.0
2/4
3/5
1/4
1/5
10.3.5.0
R2
R3
1/1
R4
LHR
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RP
Who?
Where?
RPF Nbr?
LHR#sh ip pim rp 239.1.1.1
Group: 239.1.1.1, RP: 2.2.2.2, uptime 00:00:39, expires never
LHR#sh ip pim rp mapping 239.1.1.1
PIM Group-to-RP Mappings
Group(s): 224.0.0.0/4, Static-Override
RP: 2.2.2.2 (?)
ASM Troubleshooting: Shared Tree
LHR Sends PIM (*,G) Join 1b
RP
2.2.2.2
10.4.5.0
2/4
3/5
1/4
1/5
10.3.5.0
R2
R3
1/1
R4
LHR
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RP
Who?
Where?
RPF Nbr?
LHR#show ip mroute (*, 239.1.1.1), 00:08:18/00:02:46, RP 2.2.2.2, flags: SJC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/1, Forward/Sparse, 00:08:18/00:02:46, H
LHR#show ip rpf 2.2.2.2 RPF information for ? (2.2.2.2) failed, no route exists
LHR#show ip route 2.2.2.2 % Network not in table
ASM Troubleshooting: Shared Tree
Problem:
LHR doesn’t know where the RP is for this
group.
Issue:
RP address not in RIB of LHR – routing
problem
LHR Sends PIM (*,G) Join 1b
RP
2.2.2.2
10.4.5.0
2/4
3/5
1/4
1/5
10.3.5.0
R2
R3
1/1
R4
LHR
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RP
Who?
Where?
RPF Nbr?
ASM Troubleshooting: Shared Tree
LHR#show ip route 2.2.2.2 2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/42] via 10.4.5.4, Gig 1/5
[110/42] via 10.3.5.3, Gig 1/4
Note:
Routing problem fixed. LHR now has
2 equal cost paths to the RP.
LHR Sends PIM (*,G) Join 1b
RP
2.2.2.2
10.4.5.0
2/4
3/5
1/4
1/5
10.3.5.0
R2
R3
1/1
R4
LHR
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RP
Who?
Where?
RPF Nbr?
ASM Troubleshooting: Shared Tree
LHR#show ip mroute
(*, 239.1.1.1), 00:08:18/00:02:46, RP 2.2.2.2, flags: SJC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/1, Forward/Sparse, 00:08:18/00:02:46, H
Problem:
LHR doesn’t know who the RPF
neighbor is for the shared tree for this
group.
LHR Sends PIM (*,G) Join 1b
RP
2.2.2.2
10.4.5.0
2/4
3/5
1/4
1/5
10.3.5.0
R2
R3
1/1
R4
LHR
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RP
Who?
Where?
RPF Nbr?
LHR#show ip rpf 2.2.2.2
RPF information for ? (2.2.2.2) failed, no route exists
ASM Troubleshooting: Shared Tree
LHR#show ip pim neighbor No PIM neighbors listed
Problem:
LHR doesn’t know who the RPF neighbor
is for the shared tree for this group.
LHR Sends PIM (*,G) Join 1b
RP
2.2.2.2
10.4.5.0
2/4
3/5
1/4
1/5
10.3.5.0
R2
R3
1/1
R4
LHR
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LHR#show ip pim neighbor
PIM Neighbor Table
Mode: B - Bidir Capable, DR - Designated Router, N - Default DR Priority,
P - Proxy Capable, S - State Refresh Capable
Neighbor Interface Uptime/Expires Ver DR
Address
Prio/Mode
10.3.5.3 GigabitEthernet1/4 00:17:57/00:01:21 v2 1 /
10.4.5.4 GigabitEthernet1/5 00:17:56/00:01:31 v2 1 / S P
ASM Troubleshooting: Shared Tree
Note:
“ip pim sparse-mode” added to
Gig1/4 and Gig1/5 on LHR.
LHR Sends PIM (*,G) Join 1b
RP
2.2.2.2
10.4.5.0
2/4
3/5
1/4
1/5
10.3.5.0
R2
R3
1/1
R4
LHR
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ASM Troubleshooting: Shared Tree
IP Multicast Best Practices for Enterprise Customers
“By default, if ECMP paths are available, the RPF for multicast traffic will be based on the highest IP address. This method is referred to as
the highest PIM neighbor behavior and is consistent with RFC 2362 for PIM Sparse mode but also applies to PIM-Bidir and PIM-SSM.”
http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6552/ps6592/whitepaper_c11-474791.html
Question:
Why was 10.4.5.4 chosen as the RPF neighbor?
Answer:
If ECMP are available, the RPF for the
multicast traffic will be based on highest
IP address for the RPF neighbor
LHR#show ip rpf 2.2.2.2 RPF information for ? (2.2.2.2) RPF interface: GigabitEthernet1/5 RPF neighbor: ? (10.4.5.4) RPF route/mask: 2.2.2.2/32 RPF type: unicast (ospf 1)
LHR Sends PIM (*,G) Join 1b
RP
2.2.2.2
10.4.5.0
2/4
3/5
1/4
1/5
10.3.5.0
R2
R3
1/1
R4
LHR
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RP
Who?
Where?
RPF Nbr?
ASM Troubleshooting: Shared Tree
LHR (R5) sends a PIM
(*,G) To R4
1b
Note:
LHR now has all the information it
needs to send a PIM (*,G) join to its
RPF neighbor.
LHR#show ip mroute
(*, 239.1.1.1), 00:36:39/00:02:56, RP 2.2.2.2, flags: SJC
Incoming interface: Gig 1/5, RPF nbr 10.4.5.4
Outgoing interface list:
Gig 1/1, Forward/Sparse-Dense, 00:08:08/00:02:56, H
*,G
IIF
OIL
RPF nbr
RP flags
LHR Sends PIM (*,G) Join 1b
RP
2.2.2.2
10.4.5.0
2/4
3/5
1/4
1/5
10.3.5.0
R2
R3
1/1
R4
LHR
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ASM Troubleshooting: Shared Tree
RP
R2
R3
R4
R4 (an IR) sends a PIM (*,G)
To R2 (RP)
1c
LHR
RP
Who?
Where?
RPF Nbr?
R4 (an IR) sends a PIM (*,G)
To R2 (RP)
1c
IR Sends PIM (*,G) Join 1c
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LHR#show ip mroute 239.1.1.1
(*, 239.1.1.1), 00:36:39/00:02:56, RP 2.2.2.2, flags: SJC
Incoming interface: GigabitEthernet1/5, RPF nbr 10.4.5.4
Outgoing interface list:
Gig 1/1, Forward/Sparse-Dense, 00:08:08/00:02:56, H
LHR#telnet 10.4.5.4
Trying 10.4.5.4 ... Open
R4#show ip mroute 239.1.1.1
(*, 239.1.1.1), 00:48:49/00:02:33, RP 2.2.2.2, flags: S
Incoming interface: Gig 3/3, RPF nbr 10.2.4.2, RPF-MFD
Outgoing interface list:
Gig 3/5, Forward/Sparse, 00:47:16/00:02:33, H
ASM Troubleshooting: Shared Tree
RP
Who?
Where?
RPF Nbr?
RP = 2.2.2.2 10.2.4.0
10.4.5.0
0/3
3/3 3/5
1/5
R2
R3
1/1
R4
LHR
Note:
Telnetting backwards towards the
root is a good way to troubleshoot.
IR Sends PIM (*,G) Join 1c
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 53 53
R4#telnet 10.2.4.2
Trying 10.2.4.2... Open
R2#show mrib route 239.1.1.1
(*,239.1.1.1) RPF nbr: 2.2.2.2 Flags: C
Up: 00:52:12
Incoming Interface List
Decapstunnel0 Flags: A, Up: 00:52:12
Outgoing Interface List
GigabitEthernet0/0/0/3 Flags: F NS, Up: 00:52:12
ASM Troubleshooting: Shared Tree
R4 (an IR) sent a PIM (*,G)
To R2 (RP)
1c
Note:
R4 had all the information it needed
to send a PIM (*,G) join to its RPF
neighbor. RP = 2.2.2.2
10.2.3.0
10.2.4.0 10.4.5.0
0/2
0/3
3/3
2/2 2/4
3/5
1/4
1/5
10.3.5.0
R2
R3
R4
LHR
IR Sends PIM (*,G) Join 1c
1/1
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 54 54
ASM Troubleshooting: Shared Tree
(*,G) from LHR towards the RP 1
RP
R2
R3
R4
Receiver sends
IGMP Membership Report
1a
LHR (R5) sends a PIM (*,G)
To R4
1b
R4 (an IR) sends a PIM (*,G)
To R2 (RP)
1c
LHR
(*,G) Between RP and LHR
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 55 55
R1 R2
ASM Troubleshooting Source Tree***
FHR receives
Multicast Data
2a
RP FHR
2b
FHR registers source with RP
FHR registers source with RP
RP builds S,G Back Towards Source
2
2c
RP builds S,G Back Towards Source
***When a shared MDT is already active for that group on the RP
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 56 56
R1 R2
ASM Troubleshooting Source Tree
FHR receives
Multicast Data
2a
RP FHR
FHR receives Multicast Data
2a
FHR Receives Multicast Data 2a
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 57 57
10.1.2.0
3/1 0/1 R1 R2
S: 200.1.1.100
G: 239.1.1.1
FHR
R1#show ip mroute Empty
R1#show run interface gig3/2 interface GigabitEthernet3/2
no switchport
ip address 200.1.1.1 255.255.255.0
3/2
ASM Troubleshooting Source Tree
Problem:
FHR not seeing multicast traffic
Issue:
PIM not enabled on interface of Source
FHR receives
Multicast Data
2a
RP
Other Things to Look For:
Layer 1 issues, Layer 2 issues, Access-lists.
FHR Receives Multicast Data 2a
ip pim sparse-mode
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 58 58
R1#show ip mroute (*, 239.1.1.1), 00:02:17/00:00:42, RP 0.0.0.0, flags: SP
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list: Null
Note:
We see that a (*,G) for that group has been
built.
10.1.2.0
3/1 0/1 R1 R2
S: 200.1.1.100
G: 239.1.1.1
FHR
3/21
RP
ASM Troubleshooting Source Tree
FHR Receives Multicast Data 2a
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 59 59
ASM Troubleshooting Source Tree
R1 R2
RP FHR
2b
FHR registers source with RP
2b
FHR registers source with RP
FHR Registers Source with RP 2b
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 60 60
R1#show ip mroute (*, 239.1.1.1), 00:02:17/00:00:42, RP 0.0.0.0, flags: SP
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list: Null
Note:
We see that a (*,G) for that group has been built.
Question:
Why is there no (S,G)?
10.1.2.0
3/1 0/1 R1 R2
S: 200.1.1.100
G: 239.1.1.1
FHR
3/21
RP
ASM Troubleshooting Source Tree
FHR Registers Source with RP 2b
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 61 61
3/21
R1#show ip mroute 239.1.1.1 count
IP Multicast Statistics
2 routes using 1230 bytes of memory
2 groups, 0.00 average sources per group
Forwarding Counts: Pkt Count/Pkts per second/Avg Pkt Size/Kilobits per second
Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)
Group: 239.1.1.1, Source count: 0, Packets forwarded: 0, Packets received: 6027
RP-tree: Forwarding: 0/0/0/0, Other: 6027/6026/1 RPF failed
ASM Troubleshooting Source Tree
FHR
10.1.2.0
3/1 0/1 R1 R2
RP
FHR Registers Source with RP 2b
S: 200.1.1.100
G: 239.1.1.1
Note:
We see that a (*,G) for that group has been built.
Question:
Why is there no (S,G)?
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 62 62
3/21
R1#show ip mroute (*, 239.1.1.1), 00:02:17/00:00:42, RP 0.0.0.0, flags: SP
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list: Null
ASM Troubleshooting Source Tree
FHR
10.1.2.0
3/1 0/1 R1 R2
RP
Problem:
FHR does not know who the RP is for
this group.
RP
Who?
Where?
RPF Nbr?
R1#sh ip rpf 2.2.2.2
RPF information for ? (2.2.2.2) failed, no route exists
FHR Registers Source with RP 2b
S: 200.1.1.100
G: 239.1.1.1
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 63 63
RP
Who?
Where?
RPF Nbr?
3/21
R1#sh ip pim rp mapping 239.1.1.1
PIM Group-to-RP Mappings
Group(s): 224.0.0.0/4, Static-Override
RP: 2.2.2.2 (?)
ip pim rp-address 2.2.2.2 override
R1#show ip mroute (*, 239.1.1.1), 00:02:17/00:00:42, RP 2.2.2.2, flags: SP
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list: Null
ASM Troubleshooting Source Tree
FHR
10.1.2.0
3/1 0/1 R1 R2
RP = 2.2.2.2
• Static
• Auto-rp
• BSR
Note:
RP information can be shared 3 ways
FHR Registers Source with RP 2b
S: 200.1.1.100
G: 239.1.1.1
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 64 64
RP
Who?
Where?
RPF Nbr?
R1#show ip rpf 2.2.2.2 RPF information for ? (2.2.2.2) failed, no route exists
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/2] via 10.1.2.2, 01:11:17, Gig3/1
R1#show ip route 2.2.2.2
R1#show ip pim neighbor No PIM neighbors
ASM Troubleshooting Source Tree
Problem:
FHR doesn’t know who the RPF
neighbor is for the shared tree for this
group.
3/21
FHR
10.1.2.0
3/1 0/1 R1 R2
S: 200.1.1.100
G: 239.1.1.1
RP = 2.2.2.2
FHR Registers Source with RP 2b
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 65 65
R1#show ip mroute
(*, 239.1.1.1), 00:02:45/stopped, RP 2.2.2.2, flags: SPF
Incoming interface: Gig3/1, RPF nbr 10.1.2.2, RPF-MFD
Outgoing interface list: Null
(200.1.1.100, 239.1.1.1), 00:01:34/00:02:59, flags: PFT
Incoming interface: Gig3/21, RPF nbr 0.0.0.0, Registering (data-header), Partial-SC
Outgoing interface list: Null
ASM Troubleshooting Source Tree
Note:
“ip pim sparse-mode” added to Gig3/1 on
FHR (R1) 3/21
FHR
10.1.2.0
3/1 0/1 R1 R2
RP = 2.2.2.2
S: 200.1.1.100
G: 239.1.1.1
FHR Registers Source with RP 2b
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 66 66
R1 R2
ASM Troubleshooting Source Tree
RP FHR
2c
RP builds S,G Back Towards Source
2c
RP builds S,G Back Towards Source
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 67 67
3/21
R1#show ip mroute
(*, 239.1.1.1), 00:02:45/stopped, RP 2.2.2.2, flags: SPF
Incoming interface: Gig3/1, RPF nbr 10.1.2.2, RPF-MFD
Outgoing interface list: Null
(200.1.1.100, 239.1.1.1), 00:01:34/00:02:59, flags: PFT
Incoming interface: Gig3/21, RPF nbr 0.0.0.0, Registering (data-header), Partial-SC
Outgoing interface list: Null
ASM Troubleshooting Source Tree
FHR
10.1.2.0
3/1 0/1 R1 R2
RP
Problem:
(S,G) stuck in “registering” on FHR (R1)
S: 200.1.1.100
G: 239.1.1.1
FHR Registers Source with RP 2b
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 68 68
R1#show proc cpu
(note: 1 mcast stream is being sent at Tx rate of 20Mbps)
CPU utilization for five seconds: 74%/31%; one minute: 73%; five
minutes: 41%
PID 5Sec 1Min 5Min TTY Process
156 42.31% 41.93% 23.57% 0 IP Input
ASM Troubleshooting Source Tree
Note:
Not only is the (S,G) stuck in registering, but
the CPU on FHR is also higher than normal. 10.1.2.0
3/1 0/1 R1 R2
RP FHR
Question:
Is the high CPU related to our (S,G) that is
stuck in registering? S: 200.1.1.100
G: 239.1.1.1
FHR Registers Source with RP 2b
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 69 69
R1#sh int summary | exclude ^
* GigabitEthernet3/1 0 0 0 0 0 0 20079000 2385 0
* GigabitEthernet3/21 24 96 0 0 19614000 2393 0 0 0
There is a space after ^
RXBS: rx rate (bits/sec) TXBS: tx rate (bits/sec)
RXPS: rx rate (pkts/sec) TXPS: tx rate (pkts/sec)
ASM Troubleshooting Source Tree
10.1.2.0
3/1 0/1 R1 R2
RP
Answer:
We actually have only 2 interfaces that are
up/up on R1. So yes, the high CPU is
related to the multicast traffic stream
Question:
Is the high CPU related to our (S,G) that is
stuck in registering?
FHR
S: 200.1.1.100
G: 239.1.1.1
FHR Registers Source with RP 2b
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 70 70
R2#show pim rpf 200.1.1.100
* 200.1.1.100/32 [-1/-1]
via Null with rpf neighbor 0.0.0.0
R2#show route 200.1.1.100
% Network not in table
ASM Troubleshooting Source Tree
FHR
10.1.2.0
3/1 0/1 R1 R2
RP
Question:
Why is the FHR having higher CPU?
Clue:
OIL on FHR for (S,G) is null
Note:
S,G tree will get built backwards from the RP.
So troubleshoot backwards from RP.
FHR
S: 200.1.1.100
G: 239.1.1.1
FHR Registers Source with RP 2b
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 71 71
FHR
ASM Troubleshooting Source Tree***
RP
E0
Register Stop to the FHR
Mcast data Mcast packet is encapsulated into
unicast PIM packet:
Destination IP is the RP.
PIM header type is Register
Mcast data Dest IP=RP
RP sends PIM (S,G) Join Back Towards
Source if there is an active shared tree
for that G
Mcast data Once the RP sees the packets
come in on the (S,G), it sends a
unicast Register Stop
***When a shared MDT is already
active for that group on the RP
Question:
Why is the FHR having higher CPU?
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 72 72
Source
Who?
Where?
RPF Nbr?
R2#show pim rpf 200.1.1.100
* 200.1.1.100/32 [-1/-1]
via Null with rpf neighbor 0.0.0.0
R2#show route 200.1.1.100
% Network not in table
ASM Troubleshooting Source Tree
FHR
10.1.2.0
3/1 0/1 R1 R2
RP
Problem:
RP doesn’t know where the Source
is for this group.
Issue:
Source address not in RIB of RP –
routing problem
FHR
S: 200.1.1.100
G: 239.1.1.1
FHR Registers Source with RP 2b
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 73 73
Source
Who?
Where?
RPF Nbr?
R2#show mrib route
(200.1.1.100,239.1.1.1) RPF nbr: 10.1.2.1 Flags: L
Up: 00:50:36
Incoming Interface List
GigabitEthernet0/1 Flags: A, Up: 00:11:56
Outgoing Interface List
GigabitEthernet0/3 Flags: F NS, Up: 00:49:00
ASM Troubleshooting Source Tree
R2#show pim rpf 200.1.1.100 * 200.1.1.100/32 [110/2]
via Gig /0/1 with rpf neighbor 10.1.2.1
Note:
Fix routing problem. RP now has
Source in its RIB.
FHR
10.1.2.0
3/1 0/1 R1 R2
RP FHR
S: 200.1.1.100
G: 239.1.1.1
FHR Registers Source with RP 2b
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 74 74
10.1.2.0
3/1 0/1 R1 R2
RP
R1#show ip mroute
(*, 239.1.1.1), 00:10:47/stopped, RP 2.2.2.2, flags: SPF
Incoming interface: GigabitEthernet3/1, RPF nbr 10.1.2.2, RPF-MFD
Outgoing interface list: Null
(200.1.1.100, 239.1.1.1), 00:10:47/00:03:20, flags: FT
Incoming interface: GigabitEthernet3/2, RPF nbr 0.0.0.0, RPF-MFD
Outgoing interface list:
GigabitEthernet3/1, Forward/Sparse, 00:03:21/00:03:12, H
ASM Troubleshooting Source Tree
Note:
Going back to FHR (R1) with this issue
fixed we now see that the (S,G) is no
longer stuck in registering and the CPU
is no longer high.
FHR
S: 200.1.1.100
G: 239.1.1.1
FHR Registers Source with RP 2b
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 75 75
R1 R2
CPU utilization for five seconds: 0%/0%
R1#show proc cpu
ASM Troubleshooting Source Tree
Note:
Going back to FHR (R1) with this issue
fixed we now see that the (S,G) is no
longer stuck in registering and the CPU
is no longer high.
10.1.2.0
3/1 0/1
RP FHR
R1 R2
S: 200.1.1.100
G: 239.1.1.1
FHR Registers Source with RP 2b
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 76 76
ASM Troubleshooting Source Tree Wireshark Sniffing*
10.1.2.0
3/1 0/1 S: 200.1.1.100
G: 239.1.1.1
RP FHR
*Not a complete Wireshark capture
** Wireshark reporting inner source/dest
R1 R2
RP Sending Register Stop
PIM Unicast Register w/ encapsulated
mcast data frame**
R2 sending a PIM
Join for (S,G)
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 77 77
ASM Troubleshooting Source Tree Wireshark Sniffing*
PIM Unicast Register w/ Encapsulated mcast Data Frame**
*Not a complete Wireshark capture
** Wireshark reporting inner source/dest
Source IP=10.1.2.1
Dest IP=2.2.2.2
Source IP=10.1.2.100
Dest IP=239.1.1.1
PIM
Register
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 78 78
ASM Troubleshooting Source Tree Wireshark Sniffing*
R2 Sending a PIM Join for (S,G)
*Not a complete Wireshark capture
Source IP=10.1.2.2
Dest IP=224.0.0.13
Group 239.1.1.1
Source 200.1.1.100
RPF Nbr
Geek - o - meter
PIM
Join/Prune
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 79 79
ASM Troubleshooting Source Tree Wireshark Sniffing*
RP Sending Register Stop
*Not a complete Wireshark capture
Source IP=2.2.2.2
Dest IP=10.1.2.1
Group 239.1.1.1
PIM
Register-Stop
Source 200.1.1.100
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 80 80
Case Study Source Registration Doesn‘t Stop
Potential Reasons for “Black Hole”
1. Source not known in IGP at RP or some IR on the way back to the source (this is the situation we just covered)
2. Usual suspects for any kind of packet loss (physical, firewall, ACL, etc)
3. Missing PIM Neighbor Relationship
4. Multicast Boundary Configured for this Multicast Group
S: 200.1.1.100
G: 239.1.1.1
RP FHR Mcast data
RP Wants to Join (S,G)
Registering of Source to the RP
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 81 81
10.1.2.0
3/1 0/1 R1 R2
S: 200.1.1.100
G: 239.1.1.1
RP
(S,G) Between RP and FHR
Registering of Source to the RP
RP building S,G Back Towards Source
2
ASM Troubleshooting Source Tree
FHR
“The default behavior of PIM-SM is that routers with directly connected members will join the shortest path tree as soon as they detect a new multicast source.”
PIM-SM Frequently Forgotten Fact
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 83 83
R1 R2
R3
R4
LHR Cutting over to SPT (S,G)
3
RP FHR
LHR
ASM Troubleshooting Joining the SPT
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 84 84
LHR Cutting over to SPT (S,G)
(PIM (S,G) Joins towards FHR for source
3
10.4.5.0
10.3.5.0
R1 R2
R3
R4
LHR Builds Shortest Path Tree (S,G) Back Towards Source
1. If SPT Threshold is not infinity (default 0), when the mcast stream comes into the LHR it will try to cutover to the shortest path tree
2. LHR Now must answer 3 questions before sending (S,G) Join
Source
Who?
Where?
RPF Nbr?
LHR
FHR RP
LHR Cuts over to the SPT
ASM Troubleshooting Joining the SPT
3
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 85 85
MRT(0): RPF lookup for 200.1.1.100[0.0.0.0] (200.1.1.100) returned Gig3/2 10.1.5.1
MRT(0): (200.1.1.100,239.1.1.1), RPF change from /0.0.0.0 to Gig3/2/10.1.5.1
MRT(0): Reset the z-flag for (200.1.1.100, 239.1.1.1)
MRT(0): Create (200.1.1.100,239.1.1.1), RPF Gig3/2/10.1.5.1
MRT(0): WAVL Insert interface: Gig3/11 in (200.1.1.100,239.1.1.1) Successful
MRT(0): set min mtu for (200.1.1.100, 239.1.1.1) 18010->1500
MRT(0): Add Gig3/11/239.1.1.1 to the olist of (200.1.1.100, 239.1.1.1), Forward state - MAC built
PIM(0): Insert (200.1.1.100,239.1.1.1) join in nbr 10.1.5.1's queue
MRT(0): Set the J-flag for (200.1.1.100, 239.1.1.1)
PIM(0): Building Join/Prune packet for nbr 10.1.5.1
PIM(0): Adding v2 (200.1.1.100/32, 239.1.1.1), S-bit Join
PIM(0): Send v2 join/prune to 10.1.5.1 (Gig3/2)
S: 200.1.1.100
G: 239.1.1.1
3/1 0/1 0/3 3/3
R1 R2 R4
3/5
3/2
FHR
LHR
ASM Troubleshooting Joining the SPT
RP
Geek - o - meter
RPF lookup for Source changes from
/0.0.0.0 to Gig3/2/10.1.5.1
Create the (S,G)
Send the PIM (S,G) Join
LHR Cuts over to the SPT 3
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 87 87
R1 R2
R3
R4
LHR Cutting over to SPT (S,G)
3
RP FHR
LHR
(S,G) Between LHR and FHR
ASM Troubleshooting Joining the SPT
LHR Cuts over to the SPT 3
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 88 88
Vlan 110 .3
.2
RP
(*,G) and (S,G) from LHR DR
The LH DR is responsible for sending the PIM (*,G) Join towards the RP
The LH DR will also be responsible for cutting over to the (S,G) tree
R3
R4
Last Hop Designated Router Responsibilities
ASM Designated Routers Receivers
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 89 89
Multicast DR
R1
R3
R2
R4
.3
.2
Mcast Data 1
FH Designated Router registers Source to the RP
2
The FH DR is responsible for registering the Source/Group with the RP
First Hop Designated Router Responsibilities
RP
ASM Designated Routers Sources
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 90 90
Multicast DR
10.2.3.0
10.2.4.0
R1
R3
R2
R4
.3
.2
Mcast Data 1
FH Designated Router registers Source to the RP
2
Question:
Who will be the RPF neighbor chosen by R2 for this PIM (S,G) Join? (assuming equal cost paths to the source)
RP
ASM Designated Routers Sources
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 91 91
Multicast DR
10.2.3.0
10.2.4.0
R1
R3
R2
R4
.3
.2
Mcast Data 1
Question:
Who will be the RPF neighbor chosen by
R2 for this PIM (S,G) Join? (assuming equal cost paths to the source)
RP
IP Multicast Best Practices for Enterprise Customers
“By default, if ECMP paths are available, the RPF for multicast traffic will be based on the highest IP address. This
method is referred to as the highest PIM neighbor behavior and is consistent with RFC 2362 for PIM Sparse mode but also
applies to PIM-Bidir and PIM-SSM.”
http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6552/ps6592/whitepaper_c11-474791.html
PIM (S,G) Join
3
10.2.3.3 (R3)
10.2.4.4 (R4)
Question: Which one is higher?
FH Designated Router registers Source to the RP
2
ASM Designated Routers Sources
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 92 92
R4 is router passing the traffic
R3#show ip mroute 239.1.1.1
(110.1.1.100/32, 239.1.1.1/32), uptime: 00:03:23, ip pim
Incoming interface: Vlan110, RPF nbr: 110.1.1.100
Outgoing interface list: (count: 0)
R4#show ip mroute 239.1.1.1
(*, 239.1.1.1), 00:01:01/stopped, RP 2.2.2.2, flags: SP
Incoming interface: Gig 3/3, RPF nbr 10.2.4.2, RPF-MFD
Outgoing interface list: Null
(110.1.1.100, 239.1.1.1), 00:01:01/00:03:20, flags: T
Incoming interface: Vlan110, RPF nbr 0.0.0.0, RPF-MFD
Outgoing interface list:
Gig 3/3, Forward/Sparse, 00:01:01/00:03:28, H Notice lack of “F” (register flag) on R4
Multicast DR
10.2.3.0
10.2.4.0
R1
R3
R2
R4
.3
.2
Mcast Data
ASM Designated Routers Sources
Geek - o - meter
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 93 93
R1 R2
R3
R4
(*,G) from LHR towards the RP 1
LHR Cutting over to SPT (S,G)
3
RP FHR
LHR
ASM Troubleshooting
Registering of Source to the RP
RP sends PIM (S,G) Join Towards Source
2
SSM Specific Troubleshooting
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 95 95
R1 R2
R3
R4
(S,G) from LHR towards Source
FHR
LHR
SSM Specific Troubleshooting
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 96 96
SSM Specific Troubleshooting
R1 R2
R3
R4
(S,G) from LHR towards Source
FHR
LHR
LHR receives
IGMPv3 Membership Report
ssm1
LHR (R5) sends a PIM (S,G)
To R4
ssm2
R4 (IR) send (S,G) Join to R2
ssm3
R2 (IR) send (S,G) Join to R1(FHR)
ssm4
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 97 97
SSM Specific Troubleshooting
R1 R2
R3
R4
FHR
LHR
LHR receives
IGMPv3 Membership Report
ssm1
LHR Receives IGMPv3 Membership Report ssm1
LHR receives
IGMPv3 Membership Report
ssm1
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 98 98
SSM Specific Troubleshooting
R1 R2
R3
R4
Receiver:
100.1.1.100
LHR#show ip mroute Shows nothing but the autorp group 224.0.1.40
LHR#show ip igmp group Is completely empty except for 224.0.1.40
G 1/1
LHR#show ip pim interface gig1/1
Address Interface Ver/ Nbr Query DR DR
Mode Count Intvl Prior
100.1.1.1 Gig1/1 v2/S 0 30 1 100.1.1.1
LHR
LHR receives
IGMPv3 Membership Report
ssm1 Problem:
LHR not seeing IGMPv3 Membership Report
from Receiver
LHR Receives IGMPv3 Membership Report ssm1
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 99 99
SSM Specific Troubleshooting
Destination IP
224.0.0.22
IGMP v3
http://www.rfc-editor.org/rfc/rfc3376.txt
R1 R2
R3
R4
G 1/1
LHR
LHR receives
IGMPv3 Membership Report
ssm1 Note:
Sniffer trace of IGMPv3 Membership report
from receiver
Problem:
LHR not seeing
IGMPv3 Membership
Report from Receiver
LHR Receives IGMPv3 Membership Report ssm1
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 100 100
SSM Specific Troubleshooting
LHR#show run interface gig3/11 interface GigabitEthernet3/11
no switchport
ip address 100.1.1.1 255.255.255.0
ip pim sparse-mode
LHR#show ip igmp interface gig3/11
GigabitEthernet3/11 is up, line protocol is up
Internet address is 100.1.1.1/24
IGMP is enabled on interface
Current IGMP host version is 2
Current IGMP router version is 2
<snip>
R1 R2
R3
R4
G 1/1
LHR
Problem:
LHR not seeing IGMPv3
Membership Report
from Receiver
LHR receives
IGMPv3 Membership Report
ssm1
Issue:
IGMPv3 not enabled on interface
Other Things to Look For:
Layer 1 issues, Layer 2 issues, Access-lists.
LHR Receives IGMPv3 Membership Report ssm1
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 101 101
SSM Specific Troubleshooting
LHR#show ip igmp group g3/11
IGMP Connected Group Membership
Group Address Interface Uptime Expires Last Reporter
232.1.1.1 Gig1/1 17:53:07 stopped 100.1.1.100
Note:
“ip igmp version 3” interface command
added under gig3/11 on the LHR
R1 R2
R3
R4
G 1/1
LHR
LHR receives
IGMPv3 Membership Report
ssm1
LHR Receives IGMPv3 Membership Report ssm1
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 102 102
SSM Specific Troubleshooting
R1 R2
R3
R4
FHR
LHR
LHR (R5) sends a PIM (S,G)
To R4
ssm2
LHR (R5) sends a PIM (S,G)
To R4
ssm2
LHR Sends (S,G) Join ssm2
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 103 103
SSM Specific Troubleshooting
LHR#show ip mroute
(*, 232.1.1.1), 17:51:47/00:02:58, RP 2.2.2.2, flags: SJC
Incoming interface: GigabitEthernet3/5, RPF nbr 10.4.5.4
Outgoing interface list:
GigabitEthernet3/11, Forward/Sparse, 17:51:47/00:02:58, H
LHR#show ip mroute ssm Is completely empty
??
Flags:
D - Dense,
S - Sparse,
B - Bidir Group,
s - SSM Group
Mode of Group
ASM
SSM
R1 R2
R3
R4
G 1/1
LHR
Problem:
LHR is configured for this group
to be an ASM group, not an SSM
group.
LHR Sends (S,G) Join ssm2
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 104 104
Mode of Group
ASM
SSM
SSM Specific Troubleshooting
LHR(config)#ip pim ssm ?
default Use 232/8 group range for SSM
range ACL for group range to be used for SSM
LHR(config)#ip pim ssm default
-- http://www.iana.org/assignments/multicast-addresses/
“232.0.0.0-232.255.255.255 (232/8) Source-Specific Multicast Block”
R1 R2
R3
R4
G 1/1
LHR
Note:
Some platforms (XR) have the
232/8 group as SSM by default.
In IOS it must be configured.
If SSM Source
Who?
Where?
RPF Nbr?
LHR Sends (S,G) Join ssm2
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 105 105
SSM Specific Troubleshooting
R1 R2
R3
R4
LHR
Question:
Assuming equal cost paths to the source from the
LHR thru R3 and R4, which router will the LHR use
as its RPF neighbor?
10.4.5.0
2/4
3/5
1/5
10.3.5.0
14
LHR Sends (S,G) Join ssm2
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 106 106
SSM Specific Troubleshooting
LHR#show ip mroute
(200.1.1.100, 232.1.1.1), 00:01:24/00:01:59, flags: sTI
Incoming interface: GigabitEthernet1/5, RPF nbr 10.4.5.4
Outgoing interface list:
GigabitEthernet1/1, Forward/Sparse, 00:01:24/00:01:59, H
s - SSM Group
T - SPT-bit set
I - Received Source Specific Host Report
PIM (S,G)
Join Sent
R1 R2
R3
R4
G1/1
LHR
Mode of Group
ASM
SSM
If SSM Source
Where?
RPF Nbr?
Note:
With this group now an SSM group, the
LHR asks itself where is the Source and
who is the RPF nbr for this source.
Then it sends the (S,G) Join. 10.4.5.0
2/4
3/5
1/5
10.3.5.0
1/4
LHR Sends (S,G) Join ssm2
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 107 107
SSM Specific Troubleshooting
R1 R2
R3
R4
FHR
LHR
R4 (IR) send (S,G) Join to R2
ssm3
R4 (IR) send (S,G) Join to R2
ssm3
IR (R4) Sends (S,G) Join ssm3
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 108 108
SSM Specific Troubleshooting
R4#show ip mroute
(*, 232.1.1.1), 18:13:34/stopped, RP 2.2.2.2, flags: SP
Incoming interface: GigabitEthernet3/3, RPF nbr 10.2.4.2, Partial-SC
Outgoing interface list: Null
(200.1.1.100, 232.1.1.1), 00:00:12/00:03:17, flags:
Incoming interface: GigabitEthernet3/3, RPF nbr 10.2.4.2
Outgoing interface list:
GigabitEthernet3/5, Forward/Sparse, 00:00:12/00:03:17
??
(S,G) Join
Received
R1 R2
R3
R4
LHR
Mode of Group
ASM
SSM
Problem:
IR is configured for this group to be
an ASM group, not an SSM group. 10.4.5.0
3/5 3/3 10.2.4.0
IR (R4) Sends (S,G) Join ssm3
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 109 109
SSM Specific Troubleshooting
R4#show ip mroute
(200.1.1.100, 232.1.1.1), 00:05:41/00:02:44, flags: sT
Incoming interface: GigabitEthernet3/3, RPF nbr 10.2.4.2, RPF-MFD
Outgoing interface list:
GigabitEthernet1/5, Forward/Sparse, 00:05:41/00:02:44, H
R1 R2
R3
R4
G1/1
LHR
Mode of Group
ASM
SSM
If SSM Source
Where?
RPF Nbr?
Note:
With this group now an SSM group, the
IR (R4) asks itself where is the Source
and who is the RPF nbr for this source.
Then it sends the (S,G) Join.
10.4.5.0 3/5 3/3
10.2.4.0
IR (R4) Sends (S,G) Join ssm3
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 110 110
SSM Specific Troubleshooting
R1 R2
R3
R4
FHR
LHR
R2 (IR) send (S,G) Join to R1(FHR)
ssm4
R2 (IR) send (S,G) Join to R1(FHR)
ssm4
IR (R2) Sends (S,G) Join ssm4
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 111 111
SSM Specific Troubleshooting
R2#show pim group-map
IP PIM Group Mapping Table
(* indicates group mappings being used)
(+ indicates BSR group mappings active in MRIB)
Group Range Proto Client Groups RP address Info
224.0.1.39/32* DM perm 0 0.0.0.0
224.0.1.40/32* DM perm 1 0.0.0.0
224.0.0.0/24* NO perm 0 0.0.0.0
232.0.0.0/8* SSM config 1 0.0.0.0
224.0.0.0/4* SM config 0 2.2.2.2 RPF: De0,2.2.2.2
224.0.0.0/4 SM static 0 0.0.0.0 RPF: Null,0.0.0.0
R1 R2
R3
R4
G1/1
LHR
Note:
XR has a very useful command
“show pim group-map”
IR (R2) Sends (S,G) Join ssm4
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 112 112
SSM Specific Troubleshooting
R2#show mrib ipv4 route 232.1.1.1
(200.1.1.100,232.1.1.1) RPF nbr: 10.1.2.1 Flags:
Up: 01:22:22
Incoming Interface List
GigabitEthernet0/1/0/1 Flags: A, Up: 01:22:22
Outgoing Interface List
GigabitEthernet0/1/0/3 Flags: F NS, Up: 01:22:22
R2 sends
PIM (S,G) Join
R1 R2
R3
R4
LHR
Mode of Group
ASM
SSM
If SSM Source
Where?
RPF Nbr?
Note:
IR (R2) asks itself where is the Source
and who is the RPF nbr for this source.
Then it sends the (S,G) Join.
0/1
10.1.2.0
0/3
IR (R2) Sends (S,G) Join ssm4
G1/1
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 113 113
SSM Specific Troubleshooting
R1#show ip mroute 232.1.1.1
(200.1.1.100, 232.1.1.1), 00:00:28/00:03:01, flags: sT
Incoming interface: GigabitEthernet3/21, RPF nbr 0.0.0.0, RPF-MFD
Outgoing interface list:
GigabitEthernet3/1, Forward/Sparse, 00:00:28/00:03:01, H
R1#show ip mroute 232.1.1.1 count
Group: 232.1.1.1, Source count: 1, Pkts forwarded: 0, Pkts received: 0
Source: 200.1.1.100/32, Forwarding: 0/0/0/0, Other: 0/0/0
Note:
(S,G) MDT built all the way from the
LHR to the FHR. But note how no
traffic has yet been sent from the
source.
R2 sends
PIM (S,G) Join
R1 R2
R3
R4
LHR
0/3
3/1
10.1.2.0
G1/1
IR (R2) Sends (S,G) Join ssm4
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 114 114
SSM Specific Troubleshooting
R1 R2
R3
R4
(S,G) from LHR towards Source
FHR
LHR
LHR receives
IGMPv3 Membership Report
ssm1
LHR (R5) sends a PIM (*,G)
To R4
ssm2
R4 (IR) send (S,G) Join to R2
ssm3
R2 (IR) send (S,G) Join to R1(FHR)
ssm4
Questions
BRKIPM- 2264
Recommended Reading
© 2012 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKIPM-2264 117
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