RP Discovery Methods

Load inter-as.multicast.rp.init.cfg

#IOS-XE
config replace flash:inter-as.multicast.rp.init.cfg
 
#IOS-XR
configure
load bootflash:inter-as.multicast.rp.init.cfg
commit replace
y

Routing for IPv4 unicast and BGP IPv4/Multicast is already setup. Configure RPs in each AS as follows:

XR1 should be RP using AutoRP
CSR10 should be RP using BSR
XR2 should be RP using BSR
CSR9 should be RP using static

Configure filtering on the inter-as links so that BSR and AutoRP information does not leak to other domains.

Answer

# AS 9
#
# CSR10
ip pim bsr-candidate lo0
ip pim rp-candidate lo0
!
int GigabitEthernet2.501
 ip pim bsr-border

# CSR6
int GigabitEthernet2.562
 ip pim bsr-border
int GigabitEthernet2.569
 ip pim bsr-border

# AS 8
#
# XR2
router pim
 add ipv4
  bsr candidate-bsr 8.0.0.12 
  bsr candidate-rp 8.0.0.12
!
 int GigabitEthernet0/0/0/0.524
  bsr-border
 int GigabitEthernet0/0/0/0.562
  bsr-border

# AS 7
#
# XR1
router pim
 address-family ipv4
  auto-rp mapping-agent Loopback0 scope 255
  auto-rp candidate-rp Loopback0 scope 255 
!
multicast-routing
 add ipv4
  int GigabitEthernet0/0/0/0.501
   boundary DENY_AUTORP
!
ipv4 access-list DENY_AUTORP
 10 deny ipv4 any host 224.0.1.39
 20 deny ipv4 any host 224.0.1.40
 30 permit ipv4 any any

# XR4
multicast-routing
 add ipv4
  int GigabitEthernet0/0/0/0.524
   boundary DENY_AUTORP
  int GigabitEthernet0/0/0/0.594
   boundary DENY_AUTORP
!
ipv4 access-list DENY_AUTORP
 10 deny ipv4 any host 224.0.1.39
 20 deny ipv4 any host 224.0.1.40
 30 permit ipv4 any any

# R7
ip pim autorp listener

# AS 11
#
# CSR9
ip pim rp-address 11.0.0.9

# XR3
router pim
 address-family ipv4
  rp-address 11.0.0.9

Explanation

You should be familiar with Auto-RP and BSR on IOS-XE devices. If not, INE’s RSv5 workbook has good exercises.

On IOS-XR, you specificy the BSR using the IP address, not the interface:

# XR2
router pim
 add ipv4
  bsr candidate-bsr 8.0.0.12 
  bsr candidate-rp 8.0.0.12

On IOS-XR, the Auto-RP configuration is roughly similar. The Auto-RP groups appear to already be in the “listening” mode by default. The XRv forwards this in dense mode without any extra configuration.

# XR1
router pim
 address-family ipv4
  auto-rp mapping-agent Loopback0 scope 255
  auto-rp candidate-rp Loopback0 scope 255

On the edge routers in the domains running BSR, we must use the bsr-border feature to filter BSR messages in/out of the interface.

# XR2
router pim
 add ipv4
  int GigabitEthernet0/0/0/0.524
   bsr-border
  int GigabitEthernet0/0/0/0.562
   bsr-border

# CSR6
int GigabitEthernet2.562
 ip pim bsr-border
int GigabitEthernet2.569
 ip pim bsr-border

To filter Auto-RP messages, we must filter the multicast traffic for the group itself. Auto-RP is not a control message as in BSR (which uses PIM). We can filter the contents of the Auto-RP message using ip multicast boundary filter-autorp ACL on IOS-XE, but this command does not allow us to filter the messages altogether. Instead, we must use a general multicast boundary filter and deny the Auto-RP groups.

# XR4
multicast-routing
 add ipv4
  int GigabitEthernet0/0/0/0.524
   boundary DENY_AUTORP
  int GigabitEthernet0/0/0/0.594
   boundary DENY_AUTORP
!
ipv4 access-list DENY_AUTORP
 10 deny ipv4 any host 224.0.1.39
 20 deny ipv4 any host 224.0.1.40
 30 permit ipv4 any any