Wednesday 1 January 2020

PIM Sparse Mode (Static RP)



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
1.1.1.1          Loopback0                v2/S   0      30     1      1.1.1.1
155.1.17.1       Serial0/0                v2/S   1      30     1      0.0.0.0
155.1.12.1       Serial0/1                v2/S   1      30     1      0.0.0.0
155.1.13.1       Serial0/2                v2/S   1      30     1      0.0.0.0
155.1.14.1       Serial0/3                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 1.1.1.1/32. 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 2.2.2.2
R7#sh ip pim rp mapping
PIM Group-to-RP Mappings

Group(s): 224.0.0.0/4, Static
    RP: 2.2.2.2 (?)

See we configured on R7 about the RP but R1 popped out this error msg
R1#
*Mar  1 00:40:34.943: %PIM-6-INVALID_RP_JOIN: Received (*, 224.0.1.40) Join from 155.1.17.7 for invalid RP 2.2.2.2.
Like this configure on all the routers.



As soon as we will generate the MULTICAST TRAFFIC the next hop router from the source will generate the Unicast PIM REGISTER MSG to the RP. So lets enable the multicast traffic on R7, since R7 is a PIM Router and it’s the one who generating the multicast traffic hence it will generate the PIM Register msg.
R7#ping
Protocol [ip]:
Target IP address: 224.1.1.1
Repeat count [1]: 100000000
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Interface [All]: loopback0
Time to live [255]:
Source address: 7.7.7.7
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 100000000, 100-byte ICMP Echos to 224.1.1.1, timeout is 2 seconds:
Packet sent with a source address of 7.7.7.7

...............

RP (R2) will ack it with a PIM Register stop msg.



Now on RP (R2)we have a (S,G) entry since we got the source info from the ICMP which is encapsulated in the register msg lets check the RP mroute.

R2#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), 00:07:50/stopped, RP 2.2.2.2, flags: SP
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list: Null

(7.7.7.7, 224.1.1.1), 00:07:50/00:01:09, flags: P
  Incoming interface: Serial0/0, RPF nbr 155.1.12.1
  Outgoing interface list: Null

Note: IF the Router is DR and its generate the multicast traffic  then the PIM Register msg will not be generated by the DR. DR will be knowing the (S,G) entry.
Because the DR Will check only the incoming multicast traffic on the interface.

Now since the PIM Register msg sent by R7 and passed via R1 but still R1 will not have the (S,G) entry
R1#sh ip mroute 224.1.1.1
Group 224.1.1.1 not found

Lets have a client for a group 224.1.1.1 on R6.





R6(config)#int lo0
R6(config-if)#ip igmp join-group 224.1.1.1

Reply to request 841 from 155.1.45.6, 204 ms
Reply to request 842 from 155.1.45.6, 200 ms
Reply to request 843 from 155.1.45.6, 208 ms
Reply to request 844 from 155.1.45.6, 236 ms
Reply to request 845 from 155.1.45.6, 192 ms
Reply to request 846 from 155.1.45.6, 152 ms
Reply to request 847 from 155.1.45.6, 228 ms
Reply to request 848 from 155.1.45.6, 144 ms


R6 generate the (*,G ) PIM Join and





Now R6---R4---R1---R7 has (*,G)

R6#sh ip rpf 7.7.7.7
RPF information for ? (7.7.7.7)
  RPF interface: FastEthernet0/0
  RPF neighbor: ? (155.1.45.4)
  RPF route/mask: 7.7.7.7/32
  RPF type: unicast (ospf 1)
  RPF recursion count: 0
  Doing distance-preferred lookups across tables

R4#sh ip rpf 7.7.7.7
RPF information for ? (7.7.7.7)
  RPF interface: Serial0/0
  RPF neighbor: ? (155.1.14.1)
  RPF route/mask: 7.7.7.7/32
  RPF type: unicast (ospf 1)
  RPF recursion count: 0
  Doing distance-preferred lookups across tables

R1#sh ip rpf 7.7.7.7
RPF information for ? (7.7.7.7)
  RPF interface: Serial0/0
  RPF neighbor: ? (155.1.17.7)
  RPF route/mask: 7.7.7.7/32
  RPF type: unicast (ospf 1)
  RPF recursion count: 0
  Doing distance-preferred lookups across tables

R1#sh ip mroute
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), 00:26:09/00:03:01, RP 2.2.2.2, flags: S
  Incoming interface: Serial0/1, RPF nbr 155.1.12.2
  Outgoing interface list:
    Serial0/3, Forward/Sparse, 00:19:21/00:03:01

(7.7.7.7, 224.1.1.1), 00:26:09/00:03:26, flags: T
  Incoming interface: Serial0/0, RPF nbr 155.1.17.7
  Outgoing interface list:
    Serial0/3, Forward/Sparse, 00:19:21/00:03:01

(*, 224.0.1.40), 01:35:52/00:03:13, RP 2.2.2.2, flags: SJCL
  Incoming interface: Serial0/1, RPF nbr 155.1.12.2
  Outgoing interface list:
    Serial0/0, Forward/Sparse, 01:34:58/00:02:44
    Serial0/3, Forward/Sparse, 01:35:26/00:03:13
    Loopback0, Forward/Sparse, 01:35:52/00:02:03

R1#


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