Here we are going to
assign R2 ad R3 as the candidate RP and
R1 as the mapping agent.
Note all the router
preconfigured with the ipv4 address and OSPF is used as the routing protocol,
all routers are in area 0. PIM sparse dense mode it running.
IP ADDRESS: Fast
Ethernet 155.1.XY.X/24
Loopback X.X.X.X/32
Where X & Y is
the router host number.(X <Y)
R2(config)#ip pim
send-rp-announce loopback 0 scope 255
Once the R2
configured as the candidate R2 will be having the mroute as (S,G)
(2.2.2.2,224.0.1.39)
R2#show ip mroute
2.2.2.2 224.0.1.39 | be Inter
Interface state: Interface, Next-Hop or VCD,
State/Mode
(2.2.2.2,
224.0.1.39), 00:09:33/00:02:28, flags: PT
Incoming interface: Loopback0, RPF nbr
0.0.0.0
Outgoing interface list: Null
Now lets configure the R3 box
R3(config)#ip pim
send-rp-announce loopback 0 scope 255
R3#smr 3.3.3.3
224.0.1.39 | be Int
Interface state: Interface, Next-Hop or VCD,
State/Mode
(3.3.3.3,
224.0.1.39), 00:03:27/00:02:33, flags: PT
Incoming interface: Loopback0, RPF nbr
0.0.0.0
Outgoing interface list: Null
Lets move to the
mapping agent. R4 will be the mapping agent here. Am keeping the mapping agent
one hop away form the candidate RP. Its because the directly connected routers
will about the candidate RP.
R4(config)#ip pim
send-rp-discovery loopback 0 scope 255
As we know the egg
and the chicken problem. Since R2 and R3 are the candidate RP they should
register themselves to the mapping agent but to register they need to join
224.0.1.40 group for that they should know the RP. So solve this method we have
three solution
- PIM Sparse-Dense Mode
- Auto RP listener
- PIM dense mode for
224.0.1.39/40 other sparse
Auto listener
feature we should enable on all the routers.
Rx(config)#ip pim
autorp listener
Lets check the
mapping agent.
R4#sh ip pim rp
mapping
PIM Group-to-RP
Mappings
This system is an
RP-mapping agent (Loopback0)
Group(s) 224.0.0.0/4
RP 3.3.3.3 (?), v2v1
Info source: 3.3.3.3 (?), elected via
Auto-RP
Uptime: 00:03:04, expires: 00:02:53
RP 2.2.2.2 (?), v2v1
Info source: 2.2.2.2 (?), via Auto-RP
Uptime: 00:03:00, expires: 00:01:59
R4#
The above details
say that for all the multicast group R3 and R2 are the candidate RP's. In both
of them R3 is the Winner due to the highest IP.
The ? Is for the DNS
lookup. So lets configure the DNS lookup.
R4(config)#ip host
R3 3.3.3.3
R4(config)#ip host
R2 2.2.2.2
R4#sh ip pim rp
mapping
PIM Group-to-RP
Mappings
This system is an
RP-mapping agent (Loopback0)
Group(s) 224.0.0.0/4
RP 3.3.3.3 (R3), v2v1
Info source: 3.3.3.3 (R3), elected via
Auto-RP
Uptime: 00:09:38, expires: 00:02:20
RP 2.2.2.2 (R2), v2v1
Info source: 2.2.2.2 (R2), via Auto-RP
Uptime: 00:09:33, expires: 00:02:28
R4#
Lets have a source
for 224.1.1.1
R7#ping
Protocol [ip]:
Target IP address:
224.1.1.1
Repeat count [1]:
10000000
Datagram size [100]:
Timeout in seconds
[2]:
Extended commands
[n]: yes
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 10000000,
100-byte ICMP Echos to 224.1.1.1, timeout is 2 seconds:
Packet sent with a
source address of 7.7.7.7
..
R7 will generate
the multicast feed and as the first hop router receive the feed its checks for
the RP info. So lets check the RP info on R1.
R1#sh ip pim rp
mapping
PIM Group-to-RP
Mappings
Group(s)
224.0.0.0/4
RP 3.3.3.3 (?), v2v1
Info source: 4.4.4.4 (?), elected via
Auto-RP
Uptime: 00:26:28, expires: 00:02:15
R1 details say that
R4(4.4.4.4) update the RP(3.3.3.3) via Auto-RP.
(S,G) entry will be
seen only on R1 and R3.
R3#smr 7.7.7.7
224.1.1.1 | be Inter
Interface state: Interface, Next-Hop or VCD,
State/Mode
(7.7.7.7, 224.1.1.1),
00:23:07/00:01:55, flags: P
Incoming interface: Serial1/1, RPF nbr
155.1.13.1
Outgoing interface list: Null
As we don’t have
any receivers for the group 224.1.1.1 the OIL is NULL. Lets have a client
asking for the 224.1.1.1 group
R6(config)#int lo0
R6(config-if)#ip
igmp join-group 224.1.1.1
We are getting
reply from R6.
R6#mtrace 7.7.7.7
Type escape
sequence to abort.
Mtrace from 7.7.7.7
to 155.1.146.6 via RPF
From source (?) to
destination (?)
Querying full
reverse path...
0
155.1.146.6
-1 155.1.146.6 PIM [7.7.7.7/32]
-2 155.1.146.4 PIM [7.7.7.7/32]
-3 155.1.14.1 PIM [7.7.7.7/32]
-4 155.1.17.7 PIM [7.7.7.7/32]
-5 7.7.7.7
From trace we found
like multicast feed coming from R7---R1---R4----R6 but as we know we have a R3
as RP. Lets check why R3 is not used
R3#smr 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),
00:33:09/00:03:08, RP 3.3.3.3, flags: S
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Serial1/1, Forward/Sparse,
00:07:15/00:03:08
(7.7.7.7,
224.1.1.1), 00:33:09/00:01:53, flags: PT==========> PT is the reason
Incoming interface: Serial1/1, RPF nbr
155.1.13.1
Outgoing interface list: Null
R1 will check, its
waste of bandwidth to pass the feed to R3 and again R3 anyhow send back the
feed to R1. So R1 will send a special PIM Prune msg with RP bit set and switch
to shortest path tree.
We can assign the
RP/Group. To do this just create the access-list and match the multicast group.
R2(config)#access-list
1 permit 224.0.0.0 0.255.255.255
R2(config)#ip pim
send-rp-announce loopback 0 scope 255 group-list 1
R3(config)#access-list
1 permit 239.0.0.0 0.255.255.255
R3(config)#ip pim
send-rp-announce lo0 scope 255 group-list 1
R4#sh ip pim rp
mapping
PIM Group-to-RP
Mappings
This system is an
RP-mapping agent (Loopback0)
Group(s)
224.0.0.0/8
RP 2.2.2.2 (R2), v2v1
Info source: 2.2.2.2 (R2), elected via
Auto-RP
Uptime: 00:03:01, expires: 00:01:56
Group(s)
239.0.0.0/8
RP 3.3.3.3 (R3), v2v1
Info source: 3.3.3.3 (R3), elected via
Auto-RP
Uptime: 00:01:50, expires: 00:02:08
In Mapping agent it
don’t have any security to find whose and which multicast group it should have
the RP/Group.
To Provide this
feature cisco has RP-announce filter option
R4#sh ip
access-lists
Standard IP access
list Any
10 deny
any
Standard IP access
list Ay+Group
10 deny
any
Standard IP access
list R2
10 permit 2.2.2.2
Standard IP access
list R2_Group
10 permit 224.0.0.0, wildcard bits
0.255.255.255
Standard IP access
list R3
10 permit 3.3.3.3
Standard IP access
list R3_Group
10 permit 239.0.0.0, wildcard bits
0.255.255.255
R4(config)#ip pim
rp-announce-filter rp-list R3 group-list R3_Group
R4(config)#ip pim
rp-announce-filter rp-list R2 group-list R2_Group
R4(config)#ip pim
rp-announce-filter rp-list Any group-list Any_Group
To check this lets
do debugging
R4#
*May 31
01:09:13.083: Auto-RP(0): Received RP-announce, from 5.5.5.5, RP_cnt 1, ht 181
*May 31
01:09:13.083: Auto-RP(0): Filtered 224.0.0.0/4 for RP 5.5.5.5
*May 31
01:09:13.083: Auto-RP(0): Received RP-announce, from 5.5.5.5, RP_cnt 1, ht 181
*May 31
01:09:13.083: Auto-RP(0): Filtered 224.0.0.0/4 for RP 5.5.5.5
R4#
See R5 is been
filtered :)
R4#sh ip pim rp
mapping
PIM Group-to-RP
Mappings
This system is an
RP-mapping agent (Loopback0)
Group(s)
224.0.0.0/8
RP 2.2.2.2 (R2), v2v1
Info source: 2.2.2.2 (R2), elected via
Auto-RP
Uptime: 00:00:12, expires: 00:02:44
Group(s)
239.0.0.0/8
RP 3.3.3.3 (R3), v2v1
Info source: 3.3.3.3 (R3), elected via
Auto-RP
Uptime: 00:00:44, expires: 00:02:12
R4#
