Example for Configuring Inter-AS Multicast by Using Static RPF Peers

You can set up MSDP peer relationships between Rendezvous Points (RPs) in different PIM-SM domains in the same AS or static Reverse Path Forwarding (RPF) relationships between the RPs in different ASs so that hosts can receive multicast data from the source in another PIM-SM domain in the AS or from the source in another AS.

Networking Requirements

As shown in Figure 1, there are two ASs in the network. Each AS contains one or more PIM-SM domains; and each PIM-SM domain has 0 or 1 multicast source or receiver. MSDP peer relationships are required to be set up between PIM-SM domains to share the information about multicast sources.

Figure 1 Networking diagram of configuring inter-AS multicast by using static RPF peers

**Table 1** Data Planning
Device	Interface	IP address
FW_A	GE0/0/1	192.168.5.2/24
FW_B	GE0/0/2	192.168.2.2/24
FW_C	GE0/0/1	192.168.1.1/24
	GE0/0/2	192.168.4.1/24
	Loopback0	1.1.1.1/32
FW_D	GE0/0/1	192.168.3.2/24
FW_D	Loopback0	2.2.2.2/32
FW_E	GE0/0/2	192.168.2.1/24
FW_F	GE0/0/1	192.168.5.1/24
FW_F	Loopback0	3.3.3.3/32

Configuration Roadmap

Solution: set up an MSDP peer on RP in each PIM-SM domain. Set up static RPF peer among MSDP peers. Therefore the transmission of source information across sources is implemented without changing unicast topology. The steps are as follows:

Configure an IP address for each interface, configure OSPF in the ASs, configure External BGP (EBGP) between ASs, and configure BGP and OSPF to import routes into each other.
Enable multicast on each FW and PIM-SM on each interface, enable IGMP on the interface connected to hosts, and configure the positions of Loopback 0 interfaces, the Candidate-BSR (C-BSR), and the Candidate-RP (C-RP). The Loopback 0 interfaces on FW_C, FW_D, and FW_F act as C-BSRs and C-RPs of their PIM-SM domains.
Set up MSDP peer relationships between RPs in each domain, and the MSDP peer relationship between FW_C and FW_D and between FW_C and FW_F.
Specify a static RPF peer for an MSDP peer. The static RPF peers of FW_C are FW_D and FW_F. FW_D and FW_F has only one static RPF peer, that is, FW_C. According to RPF rules, FWs receive Source Active (SA) messages from static RPF peers.

Procedure

Configure an IP address for each interface and a unicast routing protocol.
As shown in Figure 1, configure an IP address and mask for each interface. Configure OSPF in the AS. Configure EBGP between FW_A and FW_F, FW_B, and FW_E. Configure BGP and OSPF to import routes into each other. Ensure the normal communication between FWs on the network layer. Ensure dynamic routing updates between FWs through the unicast routing protocol. The procedures are not mentioned here.
Enable multicast on each FWand PIM-SM on each interface.
# Enable multicast on each FWand enable PIM-SM on each interface. The configurations of the other FWs are similar to that of FW_C, and are not mentioned here.
```
[FW_C] multicast routing-enable
```
```
[FW_C] interface GigabitEthernet 0/0/1
```
```
[FW_C-GigabitEthernet0/0/1] pim sm
```
```
[FW_C-GigabitEthernet0/0/1] quit
```
```
[FW_C] interface GigabitEthernet 0/0/2
```
```
[FW_C-GigabitEthernet0/0/2] pim sm
```
```
[FW_C-GigabitEthernet0/0/2] quit
```
# Configure BSR boundary on GE0/0/1 of FW_A, GE0/0/2 of FW_B, GE0/0/2 of FW_E and GE0/0/1 of FW_F. The configurations of FW_B, FW_E, and FW_F are similar to that of FW_A, and are not mentioned here.
```
[FW_A] interface GigabitEthernet 0/0/1
```
```
[FW_A-GigabitEthernet0/0/1] pim bsr-boundary
```
```
[FW_A-GigabitEthernet0/0/1] quit
```
Configure the Loopback 0 interface, C-BSR, and C-RP.
Configure Loopback 0 interfaces and positions of the C-BSR and C-RP on FW_C, FW_D, and FW_F. The configurations of FW_D and FW_F are similar to that of FW_C, and are not mentioned here.
```
[FW_C] interface loopback 0
```
```
[FW_C-LoopBack0] ip address 1.1.1.1 255.255.255.255
```
```
[FW_C-LoopBack0] pim sm
```
```
[FW_C-LoopBack0] quit
```
```
[FW_C] pim
```
```
[FW_C-pim] c-bsr loopback 0
```
```
[FW_C-pim] c-rp loopback 0
```
```
[FW_C-pim] quit
```

Configure static RPF peers.

# Configure FW_D and FW_F as static RPF peers of FW_C.

[FW_C] ip ip-prefix list-df permit 192.168.0.0 16 greater-equal 16 less-equal 32

[FW_C] msdp

[FW_C-msdp] peer 192.168.3.2 connect-interface GigabitEthernet 0/0/1

[FW_C-msdp] peer 192.168.5.1 connect-interface GigabitEthernet 0/0/2

[FW_C-msdp] static-rpf-peer 192.168.3.2 rp-policy list-df

[FW_C-msdp] static-rpf-peer 192.168.5.1 rp-policy list-df

[FW_C-msdp] quit

# Configure FW_C as the static RPF peer of FW_D and FW_F. The configurations of FW_F are similar to that of FW_D, and are not mentioned here.

[FW_D] ip ip-prefix list-c permit 192.168.0.0 16 greater-equal 16 less-equal 32

[FW_D] msdp

[FW_D-msdp] peer 192.168.1.1 connect-interface GigabitEthernet 0/0/1

[FW_D-msdp] static-rpf-peer 192.168.1.1 rp-policy list-c

Verify the configuration.

# Run the display bgp peer command. You can view the BGP peer relationship between FWs. If there is no output information on FW_C, it indicates that the BGP peer relationship is not set up between FW_C and FW_D, and between FW_C and FW_F.

# Run the display msdp brief command. You can view the MSDP peer relationship between FWs. When S1 in PIM-SM1 domain sends a multicast packet, the receivers in PIM-SM2 and PIM-SM3 domains can receive it. For example, information about MSDP peers on FW_C, FW_D, and FW_F is as follows:

<FW_C> display msdp brief

MSDP Peer Brief Information of VPN-Instance: public net

  Configured   Up           Listen       Connect      Shutdown     Down

  2            2            0            0            0            0

  Peer's Address     State     Up/Down time    AS     SA Count   Reset Count

  192.168.3.2        UP        01:07:08        ?      8          0

  192.168.5.1        UP        00:16:39        ?      13         0

<FW_D> display msdp brief

MSDP Peer Brief Information of VPN-Instance: public net

  Configured   Up           Listen       Connect      Shutdown     Down

  1            1            0            0            0            0

  Peer's Address     State     Up/Down time    AS     SA Count   Reset Count

  192.168.1.1        UP        01:07:09        ?      8          0

<FW_F> display msdp brief

MSDP Peer Brief Information of VPN-Instance: public net

  Configured   Up           Listen       Connect      Shutdown     Down

  1            1            0            0            0            0

  Peer's Address     State     Up/Down time    AS     SA Count   Reset Count

  192.168.4.1        UP        00:16:40        ?      13         0

Configuration Scripts

Configuration script of FW_C is as follows:

 sysname FW_C

 multicast routing-enable

interface GigabitEthernet 0/0/1

 ip address 192.168.1.1 255.255.255.0

 pim sm

interface GigabitEthernet 0/0/2

 ip address 192.168.4.1 255.255.255.0

 pim sm

interface LoopBack0

 ip address 1.1.1.1 255.255.255.255

 pim sm

ospf 1

 area 0.0.0.0

  network 192.168.1.0 0.0.0.255

  network 192.168.4.0 0.0.0.255

  network 1.1.1.1 0.0.0.0

pim

 c-bsr LoopBack0

 c-rp LoopBack0

ip ip-prefix list-df permit 192.168.0.0 16 greater-equal 16 less-equal 32

msdp

 peer 192.168.3.2 connect-interface GigabitEthernet 0/0/1

 peer 192.168.5.1 connect-interface GigabitEthernet 0/0/2

 static-rpf-peer 192.168.3.2 rp-policy list-df

 static-rpf-peer 192.168.5.1 rp-policy list-df

return

The configuration files of FW_D and FW_F are similar to the files mentioned previously, and are not mentioned here.