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)
|
iBGP peers
|
eBGP peers
|
|
R3----R1
|
R3----R4
|
|
R3----R2
|
R3----R8
|
|
R4----R6
|
R8----R4
|
|
R6----R5
|
R6 RR, R5 Client
|
|
R6----R7
|
R6 RR, R7 Non
Client
|
|
R8----R9
|
|
Inter AS Multicast
Routing uses MSDP and PIM
- MSDP to advertise source
- PIM to build the tree and do the RPF Check
Note: To do inter AS
multicast transit over the internet all hops must run multicast.
Here R3, R4 and R8
going to be the RP. But as we already know the RP info can be populate via
static and dynamic.
In AS100 , AS200 and
AS300 RP populated via dynamic BSR. But this RP info should not pass the AS.
Lets do that.
In AS100 R2 is the
BSR and R3 is the RP.
R3(config)#ip pim
rp-candidate loopback 0
R2(config)#ip pim
bsr-candidate loopback 0
R3(config)#int s2/0
R3(config-if)#ip pim
bsr-border
R3(config-if)#int
fa1/0
R3(config-if)#ip pim
bsr-border
Lets check about the
RP info
R3#show ip pim rp
mapping
PIM Group-to-RP
Mappings
This system is a
candidate RP (v2)
Group(s) 224.0.0.0/4
RP 3.3.3.3 (?), v2
Info source: 2.2.2.2 (?), via bootstrap,
priority 0, holdtime 150
Uptime: 00:02:24, expires: 00:01:54
R3#
In AS300 we are
going to configure the RP info statically
R8#show ip pim rp
mapping
PIM Group-to-RP
Mappings
Group(s):
224.0.0.0/4, Static
RP: 8.8.8.8 (?)
R9#show ip pim rp
mapping
PIM Group-to-RP
Mappings
Group(s):
224.0.0.0/4, Static
RP: 8.8.8.8 (?)
In AS200 R5 is the
BSR and R4 is the RP.
R5(config)#ip pim
bsr-candidate loopback 0
R4(config)#ip pim
rp-candidate loopback 0
R4(config)#int s3/0
R4(config-if)#ip pim
bsr-border
R4(config-if)#int
s3/1
R4(config-if)#ip pim
bsr-border
Configure the
Multicast feed Source 1
R1#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:
1.1.1.1
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 1.1.1.1
....
As soon as we
configured the Source R1 router RP should be known the (S,G)
R3#show 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),
00:04:39/stopped, RP 3.3.3.3, flags: SP
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list: Null
(1.1.1.1,
224.1.1.1), 00:04:39/00:02:10, flags: P
Incoming interface: FastEthernet0/0, RPF nbr
155.1.23.2
Outgoing interface list: Null
To pass the Source
info we have MSDP protocol. Lets have R3, R4 and R8 as the MSDP peer. As MSDP
are the unicast TCP session based peer we should have the loopback address
reachable. To have the reachability we are going to advertise the loopback in
BGP.
R3(config)#router
bgp 100
R3(config-router)#net
3.3.3.3 mask 255.255.255.255
R4(config)#router
bgp 200
R4(config-router)#net
4.4.4.4 mask 255.255.255.255
R8(config)#router
bgp 300
R8(config-router)#net
8.8.8.8 mask 255.255.255.255
R3#ping 8.8.8.8
source 3.3.3.3
Type escape sequence
to abort.
Sending 5, 100-byte
ICMP Echos to 8.8.8.8, timeout is 2 seconds:
Packet sent with a
source address of 3.3.3.3
!!!!!
Success rate is 100
percent (5/5), round-trip min/avg/max = 36/370/664 ms
R3#ping 4.4.4.4 source 3.3.3.3
Type escape sequence
to abort.
Sending 5, 100-byte
ICMP Echos to 4.4.4.4, timeout is 2 seconds:
Packet sent with a
source address of 3.3.3.3
!!!!!
Success rate is 100
percent (5/5), round-trip min/avg/max = 356/550/656 ms
R3#
Lets have a source
R5
R5(config)#int lo0
R5(config-if)#ip
igmp join-group 224.1.1.1
R4#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),
00:02:50/00:02:38, RP 4.4.4.4, flags: S
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
FastEthernet1/0, Forward/Sparse,
00:02:50/00:02:38
(1.1.1.1,
224.1.1.1), 00:02:50/00:03:20, flags: MT
Incoming interface: Serial3/0, RPF nbr
155.1.34.3
Outgoing interface list:
FastEthernet1/0, Forward/Sparse,
00:02:50/00:02:40
Lets check the path
which it took from R5 to R1.
R5#mtrace 5.5.5.5
1.1.1.1
Type escape sequence
to abort.
Mtrace from 5.5.5.5
to 1.1.1.1 via RPF
From source (?) to
destination (?)
Querying full
reverse path...
0
1.1.1.1
-1 155.1.12.1 PIM [5.5.5.5/32]
-2 155.1.12.2 PIM [5.5.5.5/32]
-3 155.1.23.3 PIM [5.5.5.5/32]
-4 155.1.34.4 PIM [5.5.5.5/32]
-5 155.1.45.5 PIM [5.5.5.5/32]
-6 5.5.5.5
R5#traceroute
1.1.1.1 sou 5.5.5.5
Type escape sequence
to abort.
Tracing the route to
1.1.1.1
1 155.1.45.4 352 msec 92 msec 244 msec
2 155.1.34.3 644 msec 656 msec 420 msec
3 155.1.23.2 868 msec 924 msec 1092 msec
4 155.1.12.1 1268 msec 1180 msec 1236 msec
R5#
Here Multicast feed
and unicast path taking the same path. If we want to have a different path we
can use BGP attribute and change but it will effect both the unicast and as
well as unicast.
Multicast BGP is a
solution which is used to alter the path for the multicast feed without
effecting the unicast. But this cause the RPF check fail. Hence the solution
they provided is RPF check is checked first if the path available via multicast
BGP table then unicast table.
Multicast BGP is not
the routing protocol its just an BGP extension to support path alteration in
multicast tree.
We can alter the
multicast feed path from R1----R2----R3----R4----R5 to
R1----R2----R3----R8----R4---R5.
To do this we should
enable the Multicast BGP extension capability between the routers R3, R4 and
R8.
R3(config)#router
bgp 100
R3(config-router)#address-family
ipv4 multicast
R3(config-router-af)#nei
8.8.8.8 activate
R8(config)#router
bgp 100
R8(config-router)#address-family
ipv4 multicast
R8(config-router-af)#nei
3.3.3.3 activate
R8(config-router-af)#nei
4.4.4.4 activate
R4(config)#router
bgp 100
R4(config-router)#address-family
ipv4 multicast
R4(config-router-af)#nei
8.8.8.8 activate
R3#show ip bgp sum |
be Nei
Neighbor V
AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
1.1.1.1 4
100 228 237
18 0 0 03:41:49 1
2.2.2.2 4
100 174 186
18 0 0 02:49:15 0
4.4.4.4 4
200 224 231
18 0 0 02:13:39 4
8.8.8.8 4
300 257 235
18 0 0 00:10:12 4
R3#show bgp ipv4
multicast summary | be Nei
Neighbor V
AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
8.8.8.8 4
300 258 235
1 0 0 00:10:49 0
R3#
It means that we
have established the capability and no route are updated in Multicast BGP.
R3#sh ip bgp
neighbors 8.8.8.8 | in Address family
Address family IPv4 Unicast: advertised and
received
Address family IPv4 Multicast: advertised
and received
Now we must
advertise the source for which we are going to change source path.
R3(config)#router
bgp 100
R3(config-router)#address-family
ipv4 multicast
R3(config-router-af)#net
1.1.1.1 mask 255.255.255.255
R4(config)#router
bgp 200
R4(config-router)#address-family
ipv4 multicast
R4(config-router-af)#net
5.5.5.5 mask 255.255.255.255
Through the
multicast BGP all the RP will be populated with.
R3#sh bgp ipv4 mu |
be Net
Network Next Hop Metric LocPrf Weight Path
*>
1.1.1.1/32 155.1.23.2 3 32768 i
*>
5.5.5.5/32 8.8.8.8 0 300 200 i
R3#
R8#sh bgp ipv4 mu |
be Net
Network Next Hop Metric LocPrf Weight Path
*>
1.1.1.1/32 3.3.3.3 3 0 100 i
*>
5.5.5.5/32 4.4.4.4 2 0 200 i
R8#
R4#sh bgp ipv4 mu |
be Net
Network Next Hop Metric LocPrf Weight Path
*>
1.1.1.1/32 8.8.8.8 0 300 100 i
*>
5.5.5.5/32 155.1.45.5 2 32768 i
R4#
Now we check the
multicast path and unicast both will be different.
Multicast
Path
R5#mtrace 5.5.5.5
1.1.1.1
Type escape sequence
to abort.
Mtrace from 5.5.5.5
to 1.1.1.1 via RPF
From source (?) to
destination (?)
Querying full
reverse path...
0
1.1.1.1
-1 155.1.12.1 PIM [5.5.5.5/32]
-2 155.1.12.2 PIM [5.5.5.5/32]
-3 155.1.23.3 PIM/MBGP [5.5.5.5/32]
-4 155.1.38.8 PIM/MBGP [5.5.5.5/32]
-5 155.1.48.4 PIM [5.5.5.5/32]
-6 155.1.45.5 PIM [5.5.5.5/32]
-7 5.5.5.5
Unicast
Path
R5#traceroute
1.1.1.1 source 5.5.5.5
Type escape sequence
to abort.
Tracing the route to
1.1.1.1
1 155.1.45.4 804 msec 1100 msec 260 msec
2 155.1.34.3 1384 msec 1200 msec 1104 msec
3 155.1.23.2 1200 msec 1304 msec 1388 msec
4 155.1.12.1 1736 msec 1860 msec 1780 msec
R5#
Since the multicast
feed through which its receiving but its unicast to the source is not the same
hence the RPF check should fail. This can be avoided by multicast BGP.
Multicast BGP is like static route but dynamic upgrade.
Note: We can create
the MSDP group its used to avoid the SA msg reliable.
R3(config)#ip msdp
mesh-group RP_Group 4.4.4.4
R8(config)#ip msdp
mesh-group RP_Group 4.4.4.4
R8(config)#ip msdp
mesh-group RP_Group 3.3.3.3
R4(config)#ip msdp
mesh-group RP_Group 3.3.3.3
Update received from
mesh-group will not be sent back to the mesh-group routers. Mesh-Group is used
to avoid the Source Active msg loop.
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