Multicast in MPLS Backbone Case Study

假設R1(PE)-R2(PE)-R3(P)-R4(PE)為MPLS Backbone AS200的Backbone Routers；R5(CE to R4),R6(CE to R1),R7(C),R8(C)屬於AS100 CE Routers；R9(to R2)屬於AS9 CE Router。

Step 1. 設定AS200中R1,R2,R3,R4啟用multicast，提供MDT transit給MPLS VPN客戶，將不使用shared multicast tree，PIM join將永遠是(S,G)的形式。

R1:

ip multicast-routing
ip pim ssm default
!
interface S0/0
! Connect to R2(PE)
ip pim sparse-mode

R2:
ip multicast-routing
ip pim ssm default
!
interface S0/0
! Connect to R1(PE)
ip pim sparse-mode
!
interface S0/1
! Connect to R3(PE)
ip pim sparse-mode

R3:
ip multicast-routing
ip pim ssm default
!
interface S0/0
! Connect to R2(PE)
ip pim sparse-mode
!
interface S0/1
! Connect to R4(PE)
ip pim sparse-mode

R4:
ip multicast-routing
ip pim ssm default
!
interface S0/0
! Connect to R3(PE)
ip pim sparse-mode

Step 2. 設定AS100 R5,R6,R7,R8啟用multicast，在這些Router之間啟用PIMv2，R5宣告自己成為這些Routers的Rendezvous Point(RP)。

R5:

ip multicast-routing
!
interface Ethernet0/0
! Connect to R4(PE)
ip pim sparse-mode
!
interface Ethernet0/1
! Connect to R7(C)
ip pim sparse-mode
!
ip pim bsr-candidate Loopback0
ip pim rp-candidate Loopback0

R6:
ip multicast-routing
!
interface S0/0
! Connect to R1(PE)
ip pim sparse-mode

R7:
ip multicast-routing
!
interface Ethernet0/0
! Connect to R5(CE)
ip pim sparse-mode
!
interface Ethernet0/1
! Connect to R8(C)
ip pim sparse-mode

R8:
ip multicast-routing
!
interface Ethernet0/0
! Connect to R7(CE)
ip pim sparse-mode

R9:
ip multicast-routing
!
interface ATM1/0.1
! Connect to R2(PE)
ip pim sparse-mode

Step 3. 設定R1,R2,R4支持在AS9和AS100之間的multicast transit，使用group address 232.1.1.1。從R5到R6(通過AS200)資料流若超過50Kbps將不會被R2接收到；這些資料流應該使用232.1.100.0/24這個範圍內的(S,G)。

R1:
ip vrf AS100
mdt default 232.1.1.1
mdt data 232.1.100.0 0.0.0.255 threshold 50
!
interface Loopback0
ip pim sparse-mode
!
interface S0/1
! Connect to R6(CE)
ip pim sparse-mode
!
ip multicast-routing vrf AS100
!
ip mroute 124.1.4.4 255.255.255.255 S0/0
! 如果有多條路由強制封包流向避免RPF check failure

R2:
ip vrf AS9
mdt default 232.1.1.1
!
interface Loopback0
ip pim sparse-mode
!
interface ATM1/0.1
! Connect to R9(CE)
ip pim sparse-mode
!
ip multicast-routing vrf AS9

R4:
ip vrf AS100
mdt default 232.1.1.1
mdt data 232.1.100.0 0.0.0.255 threshold 50
!
interface Loopback 0
ip pim sparse-mode
!
interface Ethernet0/0
! Connect to R5(PE)
ip pim sparse-mode
!
ip multicast-routing vrf AS100
!
ip mroute 124.1.1.1 255.255.255.255 S0/0
! 如果有多條路由強制封包流向避免RPF check failure

Step 4. 進行multicast測試，當R8傳送ICMP echo封包至group address 224.8.8.8時，R6及R9都會回應ICMP echo-replies。

R6:
interface S0/0
! Connect to R1(PE)
ip igmp join-group 224.8.8.8

R9:
interface ATM1/0.1
! Connect to R2(PE)
ip igmp join-group 224.8.8.8