07-13-2023 08:05 AM - edited 07-13-2023 08:05 AM
Hi,
Below is my task to do. I have configured as per below network topology. Unicast routing is working from receiver to source and vice versa. But multicast routing is not working. I need to know the reasons for this and also the task question also.Please help me.
Task:
Only BGP is running on the routers. Each router is in its own ASN. Only the LAN networks (where servers are connected) and the loopback0 addresses are advertised via BGP using network statements. BGP synchronization is disabled. Transit networks are not advertised. There are no default networks. PIM sparse mode is configured on all interfaces and the RP is set to 3.3.3.3(Router 3) on all routers.
Router 3 is hitting 100% CPU utilization and dropping packets because of the high CPU. What could be causing this?
Solved! Go to Solution.
07-13-2023 09:17 AM - edited 07-13-2023 09:40 AM
Hi @Cisconew ,
Here's probably what is causing the high CPU on the RP (R3).
1. Multicast traffic coming from Source1 is received on R1
2. R1 encapsulates the multicast packets and send them to R3 (PIM register message with source 192.168.12.1) until it receives a PIM register stop message.
3. R3 receives the encapsulated packets from R1 and tries to send a PIM register stop message to 192.168.12.1, as this is the PIM register message source address.
4. R3 doesn't have a route to 192.168.12.1, as transit interfaces are not advertised in BGP and can't send the PIM register stop message to R1
5. it keeps receiving the PIM register messages and need to decapsulate lots of traffic, which is causing the high CPU.
Regards,
07-13-2023 10:16 AM - last edited on 07-18-2023 12:09 AM by Translator
Hi @Cisconew ,
There is two ways you can fix this issue.
1. use the command
ip pim register-source Loopback0
on R1. You also need to configure
ip pim sparse-mode on lo0
2. Inject the transit subnets in BGP.
I prefer option 1.
Regards,
07-13-2023 08:11 AM - last edited on 07-17-2023 11:29 PM by Translator
I need to See R1 and R4 config
Also
Show ip route
in R1 and R4
07-13-2023 09:10 AM - last edited on 07-17-2023 11:30 PM by Translator
Hi,
Please find below the configurations of R1 and R4
R1:
hostname R1
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
ip multicast-routing
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
redundancy
!
interface Loopback0
ip address 1.1.1.1 255.255.255.255
!
interface GigabitEthernet0/0
ip address 10.10.10.1 255.255.255.0
ip pim sparse-mode
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/1
ip address 192.168.12.1 255.255.255.0
ip pim sparse-mode
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/2
ip address 192.168.14.1 255.255.255.0
ip pim sparse-mode
duplex auto
speed auto
media-type rj45
!
router bgp 100
bgp router-id 1.1.1.1
bgp log-neighbor-changes
network 1.1.1.1 mask 255.255.255.255
network 10.10.10.0 mask 255.255.255.0
neighbor 192.168.12.2 remote-as 200
neighbor 192.168.14.4 remote-as 400
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
ip pim rp-address 3.3.3.3
!
ipv6 ioam timestamp
R4:
hostname R4
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
!
ip multicast-routing
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
redundancy
!
interface Loopback0
ip address 4.4.4.4 255.255.255.255
!
interface GigabitEthernet0/0
ip address 10.100.100.4 255.255.255.0
ip pim sparse-mode
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/2
ip address 192.168.14.4 255.255.255.0
ip pim sparse-mode
duplex auto
speed auto
media-type rj45
!
interface GigabitEthernet0/3
ip address 192.168.34.4 255.255.255.0
ip pim sparse-mode
duplex auto
speed auto
media-type rj45
!
router bgp 400
bgp router-id 4.4.4.4
bgp log-neighbor-changes
network 4.4.4.4 mask 255.255.255.255
network 10.100.100.0 mask 255.255.255.0
neighbor 192.168.14.1 remote-as 100
neighbor 192.168.34.3 remote-as 300
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
ip pim rp-address 3.3.3.3
!
ipv6 ioam timestamp
!
!
!
control-plane
07-13-2023 09:14 AM - last edited on 07-17-2023 11:31 PM by Translator
Show ip route
in R1 and R4
And config of R3
07-13-2023 09:14 AM - last edited on 07-17-2023 11:31 PM by Translator
Please find below the routing tables of R1 and R4
R1:
R1#sh ip route | b Gate
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
2.0.0.0/32 is subnetted, 1 subnets
B 2.2.2.2 [20/0] via 192.168.12.2, 00:46:28
3.0.0.0/32 is subnetted, 1 subnets
B 3.3.3.3 [20/0] via 192.168.14.4, 00:46:29
4.0.0.0/32 is subnetted, 1 subnets
B 4.4.4.4 [20/0] via 192.168.14.4, 00:46:29
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
C 10.10.10.0/24 is directly connected, GigabitEthernet0/0
L 10.10.10.1/32 is directly connected, GigabitEthernet0/0
B 10.100.100.0/24 [20/0] via 192.168.14.4, 00:46:29
192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.12.0/24 is directly connected, GigabitEthernet0/1
L 192.168.12.1/32 is directly connected, GigabitEthernet0/1
192.168.14.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.14.0/24 is directly connected, GigabitEthernet0/2
L 192.168.14.1/32 is directly connected, GigabitEthernet0/2
R4:
R4#sh ip route | b Gate
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
B 1.1.1.1 [20/0] via 192.168.14.1, 00:48:10
2.0.0.0/32 is subnetted, 1 subnets
B 2.2.2.2 [20/0] via 192.168.14.1, 00:47:41
3.0.0.0/32 is subnetted, 1 subnets
B 3.3.3.3 [20/0] via 192.168.34.3, 00:48:10
4.0.0.0/32 is subnetted, 1 subnets
C 4.4.4.4 is directly connected, Loopback0
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
B 10.10.10.0/24 [20/0] via 192.168.14.1, 00:48:10
C 10.100.100.0/24 is directly connected, GigabitEthernet0/0
L 10.100.100.4/32 is directly connected, GigabitEthernet0/0
192.168.14.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.14.0/24 is directly connected, GigabitEthernet0/2
L 192.168.14.4/32 is directly connected, GigabitEthernet0/2
192.168.34.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.34.0/24 is directly connected, GigabitEthernet0/3
L 192.168.34.4/32 is directly connected, GigabitEthernet0/3
07-13-2023 09:25 AM - last edited on 07-17-2023 11:33 PM by Translator
the BGP make path for R1 via R4 to reach R3.
that I think issue here,
you need to Make R1 path not via R4
the simple solution is
router bgp R1
neighbor R4 route-map MHM in
route-map MHM permit 10
set weight 100
07-13-2023 10:28 AM - last edited on 07-17-2023 11:35 PM by Translator
Hi @MHM Cisco World ,
I am not sure why this would be an issue. PIM register messages would still be able to get from R1 to R3. The issue that I explained before would still apply as R1 would send PIM register with a source of 192.168.14.1 and R3 does not know how to reach that address, as transit subnets are not advertised in BGP. Using
ip pim register-source Loopback0
on R1 would fix this issue.
Regards,
07-13-2023 09:45 AM - last edited on 07-17-2023 11:36 PM by Translator
Reciver's configuration;
Receiver#sh run int g 0/0
Building configuration...
Current configuration : 168 bytes
!
interface GigabitEthernet0/0
ip address 10.100.100.10 255.255.255.0
ip pim sparse-mode
ip igmp join-group 229.7.7.7
duplex auto
speed auto
media-type rj45
end
Ping is successful from Source to receiver
Receiver#ping 10.10.10.10
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.10.10.10, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 5/6/9 ms
Receiver#trace 10.10.10.10 num
Type escape sequence to abort.
Tracing the route to 10.10.10.10
VRF info: (vrf in name/id, vrf out name/id)
1 10.100.100.4 2 msec 2 msec 2 msec
2 192.168.14.1 5 msec 3 msec 4 msec
3 10.10.10.10 4 msec * 4 msec
Receiver#mtrace 10.10.10.10
Type escape sequence to abort.
Mtrace from 10.10.10.10 to 10.100.100.10 via RPF
From source (?) to destination (?)
Querying full reverse path...
0 10.100.100.10
-1 10.100.100.10 ==> 10.100.100.10 PIM/Static [default]
-2 10.100.100.4 ==> 192.168.14.4 PIM/MBGP [10.10.10.0/24]
-3 192.168.14.1 ==> 10.10.10.1 PIM_MT [10.10.10.0/24]
-4 10.10.10.10
07-13-2023 09:48 AM
Check my comment above'
You need to change path of R1 to R3.
Do this and check again.
07-13-2023 09:47 AM - last edited on 07-17-2023 11:46 PM by Translator
Source Configuration:
Source#ping 10.100.100.10
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.100.100.10, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/5/6 ms
Source#trace 10.100.100.10
Type escape sequence to abort.
Tracing the route to 10.100.100.10
VRF info: (vrf in name/id, vrf out name/id)
1 10.10.10.1 2 msec 2 msec 2 msec
2 192.168.14.4 4 msec 4 msec 4 msec
3 10.100.100.10 5 msec 5 msec *
Source#mtrace 10.100.100.10
Type escape sequence to abort.
Mtrace from 10.100.100.10 to 10.10.10.10 via RPF
From source (?) to destination (?)
Querying full reverse path...
*Jul 13 16:22:18.816: %SYS-2-BADSHARE: Bad refcount in datagram_done, ptr=E039BE0, count=0
-Traceback= 2222FEz 1C89541z 1C834ADz* switching to hop-by-hop:
0 10.10.10.10
-1
*Jul 13 16:22:30.825: %SYS-2-BADSHARE: Bad refcount in datagram_done, ptr=E03B4B8, count=0
-Traceback= 2222FEz 1C89541z 1C834ADz*
*Jul 13 16:22:33.824: %SYS-2-BADSHARE: Bad refcount in datagram_done, ptr=E03A0D8, count=0
-Traceback= 2222FEz 1C89541z 1C834ADz*
*Jul 13 16:22:36.823: %SYS-2-BADSHARE: Bad refcount in datagram_done, ptr=E03D780, count=0
-Traceback= 2222FEz 1C89541z 1C834ADz* Timed out receiving responses
Perhaps no local router has a route for source, the receiver is not
a member of the multicast group or the multicast ttl is too low.
Source#ping 229.7.7.7 repeat 10000
Type escape sequence to abort.
Sending 10000, 100-byte ICMP Echos to 229.7.7.7, timeout is 2 seconds:
......................................................................
......................................................................
......................................................................
07-13-2023 10:44 AM - last edited on 07-17-2023 11:49 PM by Translator
Hi @Cisconew ,
To fix the issue of not being able to ping the receiver, you need to remove all the multicast configuration from the receiver, except
ip igmp join-group 229.7.7.7
and reload the receiver.
Regards,
07-13-2023 11:28 AM - last edited on 07-17-2023 11:50 PM by Translator
Full configuration of Receiver:
Receiver#sh run
Building configuration...
Current configuration : 3026 bytes
!
version 15.7
!
hostname Receiver
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
ip multicast-routing
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
redundancy
interface GigabitEthernet0/0
ip address 10.100.100.10 255.255.255.0
ip pim sparse-mode
ip igmp join-group 229.7.7.7
duplex auto
speed auto
media-type rj45
!
!
ip default-gateway 10.100.100.4
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
ip route 0.0.0.0 0.0.0.0 10.100.100.4
!
ipv6 ioam timestamp
07-13-2023 11:46 AM - last edited on 07-17-2023 11:53 PM by Translator
Hi @Cisconew ,
As mentioned in my previous post, the receiver should be configured as a host, not a multicast router.
You need to do the following:
no ip routing
ip default-gateway 10.100.100.4
no ip multicast-routing
int gi0/0
no ip pim sparse-mode
It should work after.
Regards,
07-13-2023 11:58 AM - last edited on 07-17-2023 11:58 PM by Translator
Hi,
Do you think I should remove these configurations on Source host too?.Here I have given
rp address
command too.
Source#sh run
Building configuration...
hostname Source
!
!
no ip routing
!
!
!
!
!
!
ip multicast-routing
no ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
!
interface GigabitEthernet0/0
ip address 10.10.10.10 255.255.255.0
ip pim sparse-mode
no ip route-cache
duplex auto
speed auto
media-type rj45
!
ip default-gateway 10.10.10.1
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
ip pim rp-address 3.3.3.3
07-13-2023 12:18 PM - last edited on 07-18-2023 12:00 AM by Translator
Hi @Cisconew ,
The source doesn't need any multicast configuration whatsoever. So you can remove all of it.
no ip routing
no ip multicast-routing
int gi0/0
no ip pim sparse-mode
!
no ip pim rp-address 3.3.3.3
Regards,
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