Multicast: Configuring Source Specific Multicast:
·
PIM-SSM
is the protocol required for configuring Source Specific Multicast.
·
IGMPv3
is required to do source specific filtering
·
As
per RFC 4607, IPv4 uses 232.0.0.0 to 232.255.255.255 for Source specific
multicast destination addresses and are reserved for use by source-specific
applications and protocols.
·
SSM
configuration steps:
·
We
need to enable SSM by using “ip pim ssm default”, that means it uses default
range 232.0.0.0/8
·
If
we want to specify a specific range, we can use “ip pim ssm range <ACL>”
command
·
Then
we need specify IGMPv3 under the client.
·
Let
me take a small topology to configure SSM:
R1----Ser1/0--------10.1.12.0/24-------Ser1/0-----R2
·
Let me configure SSM with default range first:
R1(config)#ip
multicast-routing
R1(config)#ip
pim ssm default
R1(config)#
R1(config)#int
loop0
R1(config-if)#ip
pim sparse-dense-mode
R1(config-if)#ip
igmp version 3
R1(config-if)#int
ser1/0
R1(config-if)#ip
pim sparse-dense-mode
R1(config-if)#
R2(config)#ip
multicast-routing
R2(config)#ip
pim ssm default
R2(config)#
R2(config)#int
loop0
R2(config-if)#ip
pim sparse-dense-mode
R2(config-if)#ip
igmp version 3
R2(config-if)#ip
igmp join-group 232.2.2.2 source 1.1.1.1
R2(config-if)#
R2(config-if)#int
ser1/0
R2(config-if)#ip
pim sparse-dense-mode
·
Now, let me verify multicast connectivity by initiating the ping
from server 1.1.1.1:
R1#ping
232.2.2.2 source 1.1.1.1
Type
escape sequence to abort.
Sending
1, 100-byte ICMP Echos to 232.2.2.2, timeout is 2 seconds:
Packet
sent with a source address of 1.1.1.1
Reply
to request 0 from 10.1.12.2, 52 ms
Reply
to request 0 from 10.1.12.2, 52 ms
R1#
Observation:
·
Multicast
functionality is working fine.
·
Now, let me create SSM with acess-list:
R1#show run |
i access-li
access-list
1 permit 231.3.3.3
access-list
1 permit 231.2.2.2
R1#
R1#show
run | i ssm
ip pim ssm range 1
R1#
R2#show run |
i access-li
access-list
1 permit 231.3.3.3
access-list
1 permit 231.2.2.2
R2#
R2#show
run | i ssm
ip pim ssm range 1
R2#
R2#show
run int loop0
Building
configuration...
Current
configuration : 372 bytes
!
interface
Loopback0
ip address 2.2.2.2 255.255.255.255
ip pim sparse-mode
ip igmp join-group 232.2.2.2 source 1.1.1.1
ip igmp join-group 232.3.3.3 source 1.1.1.1
ip igmp join-group 232.4.4.4 source 1.1.1.1
ip igmp join-group 231.2.2.2 source 1.1.1.1
ip igmp join-group 235.2.2.2 source 1.1.1.1
ip igmp join-group 231.3.3.3 source 1.1.1.1
ip igmp version 3
end
R2#
·
Now, let me verify multicast connectivity by initiating the ping
from server 1.1.1.1:
R1#ping
231.2.2.2 source 1.1.1.1
Type
escape sequence to abort.
Sending
1, 100-byte ICMP Echos to 231.2.2.2, timeout is 2 seconds:
Packet
sent with a source address of 1.1.1.1
Reply
to request 0 from 10.1.12.2, 20 ms
Reply
to request 0 from 10.1.12.2, 20 ms
R1#
R1#ping
231.3.3.3 source 1.1.1.1
Type
escape sequence to abort.
Sending
1, 100-byte ICMP Echos to 231.3.3.3, timeout is 2 seconds:
Packet
sent with a source address of 1.1.1.1
Reply
to request 0 from 10.1.12.2, 40 ms
Reply
to request 0 from 10.1.12.2, 60 ms
R1#
Observation:
·
Multicast
functionality is working fine for the source addresses that were matched with
the access-list.
·
Now,
let me try pining from the other addresses, that were not matched by the ACL:
R1#ping 232.2.2.2 source 1.1.1.1
Type
escape sequence to abort.
Sending
1, 100-byte ICMP Echos to 232.2.2.2, timeout is 2 seconds:
Packet
sent with a source address of 1.1.1.1
.
R1#ping 232.3.3.3 source 1.1.1.1
Type
escape sequence to abort.
Sending
1, 100-byte ICMP Echos to 232.3.3.3, timeout is 2 seconds:
Packet
sent with a source address of 1.1.1.1
.
R1#ping 235.2.2.2 source 1.1.1.1
Type
escape sequence to abort.
Sending
1, 100-byte ICMP Echos to 235.2.2.2, timeout is 2 seconds:
Packet
sent with a source address of 1.1.1.1
.
R1#
Observation:
·
Multicast
functionality is is failing for the source addresses that were not matched with
the access-list.
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