Wednesday, 1 January 2020

PIM Sparse Mode


Same Topology and Same IP address scheme am going to use here.
But the only change is instead of running PIM Dense mode here we are running PIM Sparse mode.
Lets verify it

R1#sh ip pim interface

Address          Interface                Ver/   Nbr    Query  DR     DR
                                          Mode   Count  Intvl  Prior
10.1.17.1        Serial1/0                v2/S   1      30     1      0.0.0.0
10.1.12.1        Serial1/1                v2/S   1      30     1      0.0.0.0
10.1.13.1        Serial1/2                v2/S   1      30     1      0.0.0.0
10.1.14.1        Serial1/3                v2/S   1      30     1      0.0.0.0

That’s it we enabled the PIM Sparse Mode now lets give the Rendezvous  Point  (RP) to each router.

Here I have created a loopback address 0 on R1 with ip 10.1.1.1/24. Since all the router running OSPF all router may be reachable to this IP. And here am going to use R1 as RP.
Note: On R1 also we should give the details of RP or else R1 will pop out the error msg saying the invalid RP address.

R7(config)#ip pim rp-address 10.1.1.1

See we configured on R7 about the RP but R1 popped out this error msg
R1(config)#
*Dec 29 21:05:23.899: %PIM-6-INVALID_RP_JOIN: Received (*, 224.0.1.40) Join from 10.1.17.7 for invalid RP 10.1.1.1

Ok lets configure on all the routers.

 Lets generate some multicast traffic
R7#Ping
Protocol [ip]:
Target IP address: 224.1.1.1
Repeat count [1]: 5
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Interface [All]: loopback0
Time to live [255]:
Source address: 10.7.7.7
Type of service [0]:
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 224.1.1.1, timeout is 2 seconds:
Packet sent with a source address of 10.7.7.7
.....

Since R7 is the source the first hop router R1 will generate the PIM register msg
R1#sh ip mroute 224.1.1.1
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
       L - Local, P - Pruned, R - RP-bit set, F - Register flag,
       T - SPT-bit set, J - Join SPT, M - MSDP created entry,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report,
       Z - Multicast Tunnel, z - MDT-data group sender,
       Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 224.1.1.1), 00:03:11/stopped, RP 10.1.1.1, flags: SP
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list: Null

(10.7.7.7, 224.1.1.1), 00:02:33/00:00:27, flags: P====> Because no receiver
  Incoming interface: Serial1/0, RPF nbr 10.1.17.7
  Outgoing interface list: Null

The other router in the topology dosent know about the source.

R3#sh ip mroute 224.1.1.1
Group 224.1.1.1 not found

Now on R6 am going to simulate the receiver as on loopback 0
R6(config-if)#ip igmp join-group 224.1.1.1
R6 will send the IGMP join msg to R4. We can verify this by

R6#sh ip pim rp
Group: 224.1.1.1, RP: 10.1.1.1, uptime 02:14:00, expires never
Group: 224.0.1.40, RP: 10.1.1.1, uptime 02:54:57, expires never

R6#sh ip rpf 10.1.1.1
RPF information for ? (10.1.1.1)
  RPF interface: FastEthernet1/0
  RPF neighbor: ? (10.1.56.4)
  RPF route/mask: 10.1.1.1/32
  RPF type: unicast (ospf 1)
  RPF recursion count: 0
  Doing distance-preferred lookups across tables

R4#
*Dec 29 21:49:49.867: PIM(0): Building Periodic (*,G) Join / (S,G,RP-bit) Prune message for 224.1.1.1
*Dec 29 21:49:49.867: PIM(0): Insert (*,224.1.1.1) join in nbr 10.1.14.1's queue
*Dec 29 21:49:49.871: PIM(0): Building Join/Prune packet for nbr 10.1.14.1
*Dec 29 21:49:49.871: PIM(0): Adding v2 (10.1.1.1/32, 224.1.1.1), WC-bit, RPT-bit, S-bit Join

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