How does the multicast (PIM sparse mode) work with MSDP?

How does the multicast (PIM sparse mode) work with MSDP? 

 

In this post, I will generate the multicast environment with Nx9000v on GNS3. I will handle the multicast with PIM sparse mode.

 

1. Pre-requiste for Test environments

 

I will produce this environment to generate the multicast.

Before I make Multicast environment, I need to prepare NAT for outbound traffic and Multicast test scripts. This is the sample configuration for NAT outbound traffic.

conf t feature dhcp feature nat ! ip nat translation max-entries 1023 ! no ip dhcp relay no ipv6 dhcp relay ! inter eth 1/9 no sw ip add dhcp ip nat out no shut exit inter et 1/7 no sw ip add 100.15.5.17/16 ip nat ins no shut exit inter et 1/8 no sw ip add 100.25.5.18/16 ip nat ins no shut exit ! ip acc 1 10 per ip any any exit ! ip nat inside source list 1 interface et1/9 overload ip route 10.0.0.0/24 100.15.1.17 ip route 10.0.0.0/24 100.25.2.18 ip route 20.0.0.0/24 100.15.1.17 ip route 20.0.0.0/24 100.25.2.18 ip route 100.0.0.0/8 100.15.1.17 ip route 100.0.0.0/8 100.25.2.18 ip route 1.1.1.1/32 100.15.1.17 ip route 1.1.1.1/32 100.25.2.18 ip route 2.2.2.2/32 100.15.1.17 ip route 2.2.2.2/32 100.25.2.18 ip route 3.3.3.3/32 100.15.1.17 ip route 3.3.3.3/32 100.25.2.18 ip route 4.4.4.4/32 100.15.1.17 ip route 4.4.4.4/32 100.25.2.18 end !

Also I attach the multicast example below

mcast-receiver.py

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mcast-sender.py

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2. Configuration for default environment.

 

2-1. Configure Core swtich/router  

 

I will make full-mesh connectivity. There are four switch/router. I will name as s1, s2, s3 and s4. On those switch/router, I will run OSPF routing to announce loopback addresses for Router ID and RP point. 

s1	s2	s3	s4
conf t ! switchname s1 ! feature ospf router ospf 1 router-id 1.1.1.1 exit ! inter lo 0 ip add 1.1.1.1/32 ip router ospf 1 area 0.0.0.0 no shut exit ! inter et 1/7 no sw ip add 100.15.1.17/16 no shut exit ! inter et 1/1 no sw ip add 100.12.1.11/16 ip router ospf 1 area 0.0.0.0 no shut exit ! inter et 1/2 no sw ip add 100.13.1.12/16 ip router ospf 1 area 0.0.0.0 no shut exit ! inter et 1/3 no sw ip add 100.14.1.13/16 ip router ospf 1 area 0.0.0.0 no shut exit ! ip route 0.0.0.0/0 100.15.5.17 ip route 0.0.0.0/0 100.12.2.11 100 end !	conf t ! switchname s2 ! feature ospf router ospf 1 router-id 2.2.2.2 exit ! inter lo 0 ip add 2.2.2.2/32 ip router ospf 1 area 0.0.0.0 no shut exit ! inter et 1/8 no sw ip add 100.25.2.18/16 no shut exit ! inter et 1/1 no sw ip add 100.12.2.11/16 ip router ospf 1 area 0.0.0.0 no shut exit ! inter et 1/2 no sw ip add 100.24.2.12/16 ip router ospf 1 area 0.0.0.0 no shut exit ! inter et 1/3 no sw ip add 100.23.2.13/16 ip router ospf 1 area 0.0.0.0 no shut exit ! ip route 0.0.0.0/0 100.25.5.18 ip route 0.0.0.0/0 100.12.1.11 100 end !	conf t ! switchname s3 ! feature ospf router ospf 1 router-id 3.3.3.3 exit ! inter lo 0 ip add 3.3.3.3/32 ip router ospf 1 area 0.0.0.0 no shut exit ! inter et 1/1 no sw ip add 100.34.3.11/16 ip router ospf 1 area 0.0.0.0 no shut exit ! inter et 1/2 no sw ip add 100.13.3.12/16 ip router ospf 1 area 0.0.0.0 no shut exit ! inter et 1/3 no sw ip add 100.23.3.13/16 ip router ospf 1 area 0.0.0.0 no shut exit ! ip route 0.0.0.0/0 1.1.1.1 ip route 0.0.0.0/0 2.2.2.2 ! vlan 10 name vlan10 exit ! feature interface-vlan inter vlan10 no shut ip add 10.0.0.1/24 exit ! inter et 1/7, et 1/8 sw mode ac sw ac vlan 10 no shut exit ! ---------------------------------- ! conf t ! inter vlan 10 ip router ospf 1 area 0.0.0.0 exit ! ----------------------------------  conf t ! feature pim ! ip pim rp-address 99.99.99.99 ! inter eth 1/1, eth 1/2, eth 1/3 ip pim sparse-mode exit ! inter vlan 10 ip pim sparse-mode exit !	conf t ! switchname s4 ! feature ospf router ospf 1 router-id 4.4.4.4 exit ! inter lo 0 ip add 4.4.4.4/32 ip router ospf 1 area 0.0.0.0 no shut exit ! inter et 1/1 no sw ip add 100.34.4.11/16 ip router ospf 1 area 0.0.0.0 no shut exit ! inter et 1/2 no sw ip add 100.24.4.12/16 ip router ospf 1 area 0.0.0.0 no shut exit ! inter et 1/3 no sw ip add 100.14.4.13/16 ip router ospf 1 area 0.0.0.0 no shut exit ! ip route 0.0.0.0/0 1.1.1.1 ip route 0.0.0.0/0 2.2.2.2 ! vlan 20 name vlan20 exit ! feature interface-vlan inter vlan20 no shut ip add 20.0.0.1/24 exit ! inter et 1/7 sw mode ac sw ac vlan 20 no shut exit ! ---------------------------------- ! conf t ! inter vlan 20 ip router ospf 1 area 0.0.0.0 exit ! ----------------------------------  conf t ! feature pim ! ip pim rp-address 99.99.99.99 ! inter eth 1/1, eth 1/2, eth 1/3 ip pim sparse-mode exit ! inter vlan 20 ip pim sparse-mode exit !

In s1 and s2, there are 2 kinds of loopback addresses. One is for the switch/router ID, the other is for the RP address. For loopback address for RP, I will utilize "ghost loopback address" method. Please look at the loopback interface 1 in s1 and s2.

s1	s2
conf t ! feature pim ! inter lo 1 ip address 99.99.99.99/32 ip router ospf 1 area 0.0.0.0 ip ospf network point ip pim sparse-mode no shutdown exit ! ip pim rp-address 99.99.99.99 ! inter eth 1/1, eth 1/2, eth 1/3 ip pim sparse-mode exit !	conf t ! feature pim ! inter lo 1 ip address 99.99.99.99/24 ip router ospf 1 area 0.0.0.0 ip ospf network point ip pim sparse-mode no shutdown exit ! ip pim rp-address 99.99.99.99 ! inter eth 1/1, eth 1/2, eth 1/3 ip pim sparse-mode exit !

S1 is the main RP server in normal status. However, it will be changed to s2 when S1 is failed without IP address change. Because of this, I need MSDP (Multicast Source Discovery Protocol). I will handle in later. To announce the network with subnet of loopback interface into OSPF, "Point to Point" is necesary. Now I can see the routing table on S3 and S4 switch/router.

s3# show ip route ospf-1

s4# show ip route ospf-1

1.1.1.1/32, ubest/mbest: 1/0     *via 100.13.1.12, Eth1/2, [110/41], 3d00h, ospf-1, intra 2.2.2.2/32, ubest/mbest: 1/0     *via 100.23.2.13, Eth1/3, [110/41], 3d00h, ospf-1, intra 4.4.4.4/32, ubest/mbest: 1/0     *via 100.34.4.11, Eth1/1, [110/41], 3d00h, ospf-1, intra 20.0.0.0/24, ubest/mbest: 1/0     *via 100.34.4.11, Eth1/1, [110/80], 03:33:46, ospf-1, intra 99.99.99.0/24, ubest/mbest: 1/0     *via 100.23.2.13, Eth1/3, [110/41], 00:44:41, ospf-1, intra 99.99.99.99/32, ubest/mbest: 1/0     *via 100.13.1.12, Eth1/2, [110/41], 00:44:41, ospf-1, intra 100.12.0.0/16, ubest/mbest: 2/0     *via 100.13.1.12, Eth1/2, [110/80], 3d00h, ospf-1, intra     *via 100.23.2.13, Eth1/3, [110/80], 3d00h, ospf-1, intra 100.14.0.0/16, ubest/mbest: 2/0     *via 100.13.1.12, Eth1/2, [110/80], 3d00h, ospf-1, intra     *via 100.34.4.11, Eth1/1, [110/80], 3d00h, ospf-1, intra 100.24.0.0/16, ubest/mbest: 2/0     *via 100.23.2.13, Eth1/3, [110/80], 3d00h, ospf-1, intra     *via 100.34.4.11, Eth1/1, [110/80], 3d00h, ospf-1, intra

1.1.1.1/32, ubest/mbest: 1/0     *via 100.14.1.13, Eth1/3, [110/41], 3d00h, ospf-1, intra 2.2.2.2/32, ubest/mbest: 1/0     *via 100.24.2.12, Eth1/2, [110/41], 3d00h, ospf-1, intra 3.3.3.3/32, ubest/mbest: 1/0     *via 100.34.3.11, Eth1/1, [110/41], 3d00h, ospf-1, intra 10.0.0.0/24, ubest/mbest: 1/0     *via 100.34.3.11, Eth1/1, [110/80], 03:34:26, ospf-1, intra 99.99.99.0/24, ubest/mbest: 1/0     *via 100.24.2.12, Eth1/2, [110/41], 00:45:13, ospf-1, intra 99.99.99.99/32, ubest/mbest: 1/0     *via 100.14.1.13, Eth1/3, [110/41], 00:45:13, ospf-1, intra 100.12.0.0/16, ubest/mbest: 2/0     *via 100.14.1.13, Eth1/3, [110/80], 3d00h, ospf-1, intra     *via 100.24.2.12, Eth1/2, [110/80], 3d00h, ospf-1, intra 100.13.0.0/16, ubest/mbest: 2/0     *via 100.14.1.13, Eth1/3, [110/80], 3d00h, ospf-1, intra     *via 100.34.3.11, Eth1/1, [110/80], 3d00h, ospf-1, intra 100.23.0.0/16, ubest/mbest: 2/0     *via 100.24.2.12, Eth1/2, [110/80], 3d00h, ospf-1, intra     *via 100.34.3.11, Eth1/1, [110/80], 3d00h, ospf-1, intra

In red text above, "100.100.100.100" is the RP address for multicast. At this time, the destination should be s1. It will be changed to s2 by "100.100.100.0/24", when s1 is failed.

2-2. Configure the Host (PC, Labtop) network.

 

s3 and s4 is the gateway for each host network. In my scenario, I will use "10.0.0.0/24" for PC1 and "20.0.0.0/24" for PC2.

I have already done for the gateway above.

S3	S4
! conf t ! inter vlan 10 ip router ospf 1 area 0.0.0.0 exit ! inter eth 1/1, eth 1/2, eth 1/3 ip pim sparse-mode exit ! inter vlan 10 ip pim sparse-mode exit !	! conf t ! inter vlan 20 ip router ospf 1 area 0.0.0.0 exit ! inter eth 1/1, eth 1/2, eth 1/3 ip pim sparse-mode exit ! inter vlan 20 ip pim sparse-mode exit !

Now I will configure the PC network interface. In my case I will use "Ubuntu Desktop". In this instruction, I can see how to install "ubuntu" in GNS3. After installation, I can open the console like below.

After login, I can set the network interface like below. I need to update file in "/etc/network/interfaces".

After set both of hosts, I can send ICMP packet each other.

 

However, there is one more thing necessary. To Join and receive the multicast packet. I need to define the IGMP version on Linux host sometimes. This instruction will be helpful.

echo "2" >> /proc/sys/net/ipv4/conf/<interface>/force_igmp_version

In my case, Host 2 and Host 3 will be receiver, therefore it will be like below

 

3. Configuraton for Multicast environment.

 

3-1. Configure for default multicast 

 

In fact, I have already done for multicast routing, if you follow sample configuration. This instruction will be helpful to understand how to configure.

S1	S2	S3	S4
conf t ! feature pim ! inter lo 1 ip address 99.99.99.99/32 ip router ospf 1 area 0.0.0.0 ip ospf network point ip pim sparse-mode no shutdown exit ! ip pim rp-address 99.99.99.99 ! inter eth 1/1, eth 1/2, eth 1/3 ip pim sparse-mode exit !	conf t ! feature pim ! inter lo 1 ip address 99.99.99.99/24 ip router ospf 1 area 0.0.0.0 ip ospf network point ip pim sparse-mode no shutdown exit ! ip pim rp-address 99.99.99.99 ! inter eth 1/1, eth 1/2, eth 1/3 ip pim sparse-mode exit !	conf t ! feature pim ! ip pim rp-address 99.99.99.99 ! inter eth 1/1, eth 1/2, eth 1/3 ip pim sparse-mode exit ! inter vlan 10 ip pim sparse-mode exit !	conf t ! feature pim ! ip pim rp-address 99.99.99.99 ! inter eth 1/1, eth 1/2, eth 1/3 ip pim sparse-mode exit ! inter vlan 20 ip pim sparse-mode exit !

Now, I can test multicast routing with sample script. I can get the result like below.

I success to send multicast traffic. However, I still leave MSDP. "99.99.99.99" is the RP which is S1. I worry the S1 fail situation. MSDP is one of good solution. Please read next step.

 

3-2. Configure for MSDP.

 

Before, I configure for MSDP. Any information was not shared each other. (S1 and S2 are peer connection for MSDP). I run command "show ip msdp route" and "show ip msdp sa-cache".

Because of this, the routing information should be registered again on S2, when S1 is failed. Now, I will follow this instruction. At first, I will MSDP configuration to share source information between s1 and s2.

In above, there is "ip msdp cache-sa-state" command for caching. However, there is no command in Nx9000v in my case. Therefore, my configuration should be below.

s1	s2
feature msdp ip msdp originator-id loopback0 ip msdp peer 1.1.1.2 connect-source loopback0	feature msdp ip msdp originator-id loopback0 ip msdp peer 1.1.1.1 connect-source loopback0

I can check the status with "show ip msdp summary" 

I can also verify the status with again "show ip msdp route" and "show ip msdp sa-cache".

In fact, I can not understand this effect.

 

3-3. Verify the MSDP effect.

 

Before MSDP configuration, I will shutodown loopback 1 (RP) of S1 switch/router. In S2 switch/router, there is no multicast source information.

After sender request, the source information is updated. This is normal case

Now, I will configure MSDP. I will shutdown loopback 1 of switch/router S1 again. In S2,

Multicast routing information is updated directly.

 

Sample Configurations

S1

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S2

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S3

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S4

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S5

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Reference

 

[ 1 ] https://www.osboxes.org/ubuntu/#ubuntu-14_04-vmware

[ 2 ] https://docs.gns3.com/1RpM21DdgL2pCNtIrw6e9Yf52tRjYZIe46LMeESl-jy4/

[ 3 ] https://www.cisco.com/c/en/us/td/docs/ios/12_2/ip/configuration/guide/fipr_c/1cfmsdp.html#wp1000963

[ 4 ] https://createnetech.tistory.com/40?category=672584

[ 5 ] https://pymotw.com/2/socket/multicast.html

[ 6 ] https://sites.google.com/site/miclinuxcorner/technology/multicast-routing

[ 7 ] https://www.cisco.com/c/en/us/support/docs/ip/ip-multicast/9356-48.html#msdp