Multicast Configuration Example using Cisco XRv

Below is a configuration example for multicast (PIM-SM) using cisco XRv.

I have 4 routers with ISIS reachable. Let’s name them xrv1, xrv2, xrv3, xrv4.

The example include BSR and RP election functions

1. Enable multicast routing on loopback and physical interface

multicast-routing
address-family ipv4
interface Loopback0
enable
!
interface Loopback10000
enable
!
interface GigabitEthernet0/0/0/1
enable
!
interface GigabitEthernet0/0/0/2
enable
!
!
!

2.Enable PIM on physical interface to establish PIM neighbor

router pim
address-family ipv4
interface Loopback0
enable
!
interface GigabitEthernet0/0/0/1
enable
neighbor-filter 0001
!
interface GigabitEthernet0/0/0/2
enable
neighbor-filter 0002

Check result

RP/0/0/CPU0:Edge1#show pim neighbor
Mon Apr 17 01:39:25.916 UTC

PIM neighbors in VRF default
Flag: B – Bidir capable, P – Proxy capable, DR – Designated Router,
E – ECMP Redirect capable
* indicates the neighbor created for this router

Neighbor Address Interface Uptime Expires DR pri Flags

3.3.3.24* GigabitEthernet0/0/0/1 1d03h 00:01:24 1 B E
3.3.3.25 GigabitEthernet0/0/0/1 1d03h 00:01:26 1 (DR) B
3.3.3.22* GigabitEthernet0/0/0/2 1d03h 00:01:29 1 B E
3.3.3.23 GigabitEthernet0/0/0/2 1d03h 00:01:28 1 (DR) B
10.127.224.1* Loopback0 03:58:00 00:01:25 1 (DR) B E
200.0.0.3* Loopback10000 1d02h 00:01:27 1 (DR) B E

The reason here configuring neighbor-filter is: Xrv is connected with a “switch” by Vmware, the destination MAC and IP is a multicast MAC. Without the filter, the interface will establish neighbor with all interfaces enabled with PM. This will make result very confused. So an access-list only permit the IP on the other side of interface is configured for the neighbor filter.

3. Configure C-BSR

I configure XRv3 as C-BSR.

router pim
address-family ipv4
bsr candidate-bsr 10.127.224.3 hash-mask-len 30 priority 1

Then check the BSR election on XRv1,2,4

RP/0/0/CPU0:Edge1#show pim bsr election
Mon Apr 17 01:51:42.015 UTC
PIM BSR Election State

Cand/Elect-State Uptime BS-Timer BSR C-BSR

No-Info/Accept-Pref 00:41:08 00:02:03 10.127.224.3 [1, 30] 0.0.0.0 [0, 0]

4. Configure C-RP

I configure XRv4 as RP. Then I need to go to XRv1,2,3 to configure C-RP

router pim
address-family ipv4
bsr candidate-rp 10.127.224.4 group-list rp-group priority 192 interval 60

ipv4 access-list rp-group
10 permit ipv4 239.0.0.0 0.0.1.255 any

Check the result

RP/0/0/CPU0:Edge1#show pim bsr candidate-rp
Mon Apr 17 01:55:02.142 UTC
PIM BSR Candidate RP Info

Cand-RP mode scope priority uptime group-list
10.127.224.4 BD 16 192 00:00:00 rp-group

5. Enable IGMP to build a RPT

router igmp
interface Loopback10000
join-group 239.0.0.1
!

Check the RPT

RP/0/0/CPU0:Edge1#show pim topology
Mon Apr 17 01:57:28.732 UTC

IP PIM Multicast Topology Table
Entry state: (*/S,G)[RPT/SPT] Protocol Uptime Info
Entry flags: KAT – Keep Alive Timer, AA – Assume Alive, PA – Probe Alive
RA – Really Alive, IA – Inherit Alive, LH – Last Hop
DSS – Don’t Signal Sources, RR – Register Received
SR – Sending Registers, SNR – Sending Null Registers
E – MSDP External, EX – Extranet
MFA – Mofrr Active, MFP – Mofrr Primary, MFB – Mofrr Backup
DCC – Don’t Check Connected, ME – MDT Encap, MD – MDT Decap
MT – Crossed Data MDT threshold, MA – Data MDT Assigned
SAJ – BGP Source Active Joined, SAR – BGP Source Active Received,
SAS – BGP Source Active Sent, IM – Inband mLDP, X – VxLAN
Interface state: Name, Uptime, Fwd, Info
Interface flags: LI – Local Interest, LD – Local Dissinterest,
II – Internal Interest, ID – Internal Dissinterest,
LH – Last Hop, AS – Assert, AB – Admin Boundary, EX – Extranet,
BGP – BGP C-Multicast Join, BP – BGP Source Active Prune,
MVS – MVPN Safi Learned, MV6S – MVPN IPv6 Safi Learned

(*,224.0.1.40) DM Up: 1d03h RP: 0.0.0.0
JP: Null(never) RPF: Null,0.0.0.0 Flags:
GigabitEthernet0/0/0/1 1d03h off LI II
GigabitEthernet0/0/0/2 1d03h off LI

(192.168.210.1,232.1.1.1)SPT SSM Up: 1d03h
JP: Join(00:00:41) RPF: GigabitEthernet0/0/0/1,3.3.3.25 Flags:
Loopback10000 1d03h fwd LI II LH

(*,239.0.0.1) SM Up: 00:33:12 RP: 10.127.224.4 
JP: Join(00:00:41) RPF: GigabitEthernet0/0/0/1,3.3.3.25 Flags: LH 
Loopback10000 00:33:12 fwd LI II LH