Configure Inter-VRF Multicast without Unicast Inter-VRF Route Leaking

Introduction

This document describes how you can forward a multicast stream that comes in from a source in Virtual Routing and Forwarding (VRF) source and goes towards users in VRF receiver without doing unicast inter-VRF route leaking.

Prerequisites

Requirements

Cisco recommends that you have knowledge of PIM functionality and ASM.

Components Used

The information in this document is based on ASR1000.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, ensure that you understand the potential impact of any command.

Network Diagram

Configurations

Generate UDP multicast stream on the source.

Source#

ip sla 1

udp-echo 239.1.1.1 2000 source-ip 10.1.1.1

ip sla schedule 1 life forever start-time now

The receiver is configured with IGMP and sends IGMP membership reports.

ASR1000 router is doing the inter-vrf multicast traffic forwarding. Loopback 1 in VRF 'source' is the RP for both the VRFs.

ASR1000#

ip vrf source

rd 1:1

!

ip vrf receiver

rd 2:2

!

ip multicast-routing vrf source distributed

ip multicast-routing vrf receiver distributed


ip pim vrf source rp-address 1.1.1.1

ip pim vrf receiver rp-address 1.1.1.1


interface Loopback1

ip vrf forwarding source

ip address 1.1.1.1 255.255.255.255

ip pim sparse-mode


interface GigabitEthernet0/0/0

ip vrf forwarding source

ip address 10.1.1.2 255.255.255.0

ip pim sparse-mode


interface GigabitEthernet0/0/1

ip vrf forwarding receiver

ip address 20.1.1.2 255.255.255.0

ip pim sparse-mode

(S, G) entry is not formed in vrf 'receive' for now.

ASR1002-1#show ip mroute vrf source

IP Multicast Routing Table

Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,

L - Local, P - Pruned, R - RP-bit set, F - Register flag,

T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,

X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,

U - URD, I - Received Source Specific Host Report,

Z - Multicast Tunnel, z - MDT-data group sender,

Y - Joined MDT-data group, y - Sending to MDT-data group,

G - Received BGP C-Mroute, g - Sent BGP C-Mroute,

N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,

Q - Received BGP S-A Route, q - Sent BGP S-A Route,

V - RD & Vector, v - Vector, p - PIM Joins on route,

x - VxLAN group, c - PFP-SA cache created entry,

* - determined by Assert

Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join

Timers: Uptime/Expires

Interface state: Interface, Next-Hop or VCD, State/Mode


(*, 239.1.1.1), 00:05:01/stopped, RP 1.1.1.1, flags: SPF

Incoming interface: Null, RPF nbr 0.0.0.0

Outgoing interface list: Null

(10.1.1.1, 239.1.1.1), 00:05:01/00:02:26, flags: PFT

Incoming interface: GigabitEthernet0/0/0, RPF nbr 0.0.0.0

Outgoing interface list: Null


(*, 224.0.1.40), 00:07:03/00:02:59, RP 1.1.1.1, flags: SJCL

Incoming interface: Null, RPF nbr 0.0.0.0

Outgoing interface list:

Loopback1, Forward/Sparse, 00:07:01/00:02:59

ASR1002-X-1#sh ip mroute vrf receiver
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group,
G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
Q - Received BGP S-A Route, q - Sent BGP S-A Route,
V - RD & Vector, v - Vector, p - PIM Joins on route,
x - VxLAN group, c - PFP-SA cache created entry,
* - determined by Assert, # - iif-starg configured on rpf intf,
e - encap-helper tunnel flag
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode


(*, 239.1.1.1), 00:03:23/00:02:44, RP 1.1.1.1, flags: SJC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet0/0/1, Forward/Sparse, 00:03:23/00:02:44

In order to fix this, you need to do a VRF selection so as to pass the RPF check.

ip access-list standard 1

permit 239.1.1.1 log

exit

ip multicast vrf receiver rpf select vrf source group-list 1

Verify

Use this section to confirm that your configuration works properly.

After you perform the previously mentioned steps, the Multicast feed can be seen on the receiver.

Receiver#show flow monitor test cache format table

Cache type: Normal (Platform cache)

Cache size: 200000

Current entries: 1

High Watermark: 3


Flows added: 50

Flows aged: 49

- Inactive timeout ( 15 secs) 49


IPV4 SRC ADDR IPV4 DST ADDR TRNS SRC PORT TRNS DST PORT INTF INPUT FLOW SAMPLER ID IP TOS IP PROT ip src as ip dst as ipv4 next hop addr ipv4 src mask ipv4 dst mask tcp flags intf output bytes pkts time first time last

=============== =============== ============= ============= ==================== =============== ====== ======= ========= ========= ================== ============= ============= ========= ==================== ========== ========== ============ ============

10.1.1.1 239.1.1.1 57314 1967 Gi0/0/3 0 0x00 17 0 0 0.0.0.0 /0 /0 0x00 Null 80 1 11:09:08.082 11:09:08.082

Packet Capture on the receiver.

(S, G) entry is formed in the VRF receiver.

ASR1002-1#show ip mroute vrf receiver 239.1.1.1 
IP Multicast Routing Table 
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected, L - Local, 
P - Pruned, R - RP-bit set, F - Register flag, T - SPT-bit set, J - Join SPT, 
M - MSDP created entry, E - Extranet, X - Proxy Join Timer Running, 
A - Candidate for MSDP Advertisement, U - URD, I - Received Source Specific Host Report, 
Z - Multicast Tunnel, z - MDT-data group sender, Y - Joined MDT-data group, 
y - Sending to MDT-data group, G - Received BGP C-Mroute, g - Sent BGP C-Mroute, 
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed, 
Q - Received BGP S-A Route, q - Sent BGP S-A Route, V - RD & Vector, v - Vector, 
p - PIM Joins on route, x - VxLAN group, c - PFP-SA cache created entry, 
* - determined by Assert Outgoing interface flags: H - Hardware switched, 
A - Assert winner, p - PIM Join 
Timers: Uptime/Expires 
Interface state: 
Interface, Next-Hop or VCD, State/Mode 

(*, 239.1.1.1), 00:21:36/stopped, RP 1.1.1.1, flags: SJC
Incoming interface: Loopback1, RPF nbr 1.1.1.1, using vrf source
Outgoing interface list:
GigabitEthernet0/0/1, Forward/Sparse, 00:21:36/00:02:43

(10.1.1.1, 239.1.1.1), 00:03:55/stopped, flags: T
Incoming interface: GigabitEthernet0/0/0, RPF nbr 0.0.0.0, using vrf source
Outgoing interface list:
GigabitEthernet0/0/1, Forward/Sparse, 00:03:55/00:02:43


ASR1002-1#show ip mroute vrf source 239.1.1.1
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group,
G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
Q - Received BGP S-A Route, q - Sent BGP S-A Route,
V - RD & Vector, v - Vector, p - PIM Joins on route,
x - VxLAN group, c - PFP-SA cache created entry,
* - determined by Assert
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.1.1.1), 00:22:36/stopped, RP 1.1.1.1, flags: SJCFE
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list: Null

Extranet receivers in vrf receiver:
(*, 239.1.1.1), 00:21:54/stopped, RP 1.1.1.1, OIF count: 1, flags: SJC

(10.1.1.1, 239.1.1.1), 00:04:14/00:02:55, flags: FTE
Incoming interface: GigabitEthernet0/0/0, RPF nbr 0.0.0.0
Outgoing interface list: Null

Extranet receivers in vrf receiver:
(10.1.1.1, 239.1.1.1), 00:04:14/stopped, OIF count: 1, flags: T


ASR1002-1#show ip mfib vrf receiver 239.1.1.1
Entry Flags: C - Directly Connected, S - Signal, IA - Inherit A flag,
ET - Data Rate Exceeds Threshold, K - Keepalive
DDE - Data Driven Event, HW - Hardware Installed
ME - MoFRR ECMP entry, MNE - MoFRR Non-ECMP entry, MP - MFIB
MoFRR Primary, RP - MRIB MoFRR Primary, P - MoFRR Primary
MS - MoFRR Entry in Sync, MC - MoFRR entry in MoFRR Client.
I/O Item Flags: IC - Internal Copy, NP - Not platform switched,
NS - Negate Signalling, SP - Signal Present,
A - Accept, F - Forward, RA - MRIB Accept, RF - MRIB Forward,
MA - MFIB Accept, A2 - Accept backup,
RA2 - MRIB Accept backup, MA2 - MFIB Accept backup

Forwarding Counts: Pkt Count/Pkts per second/Avg Pkt Size/Kbits per second
Other counts: Total/RPF failed/Other drops
I/O Item Counts: HW Pkt Count/FS Pkt Count/PS Pkt Count Egress Rate in pps
VRF receiver
(*,239.1.1.1) Flags: C HW
SW Forwarding: 0/0/0/0, Other: 0/0/0
HW Forwarding: 0/0/0/0, Other: 1/1/0
GigabitEthernet0/0/1 Flags: NS
(10.1.1.1,239.1.1.1) Flags: HW
SW Forwarding: 0/0/0/0, Other: 0/0/0
HW Forwarding: 15/0/94/0, Other: 0/0/0
GigabitEthernet0/0/1 Flags: NS

Also, there is no unicast entry in the VRF receiver RIB for RP and source IP.

ASR1002-1#show ip route vrf receiver 1.1.1.1 
Routing Table: receiver % Network not in table 

ASR1002-1#show ip route vrf receiver 10.1.1.1 
Routing Table: receiver % Network not in table

Thus RPF shows as failed which is expected however, the multicast traffic will be forwarded.

ASR1002-1#show ip rpf vrf receiver 1.1.1.1 
failed, no route exists 
ASR1002-1#show ip rpf vrf receiver 10.1.1.1 
failed, no route exists 

There is another way of achieving this, which is as follows:

ip mroute vrf receiver 10.1.1.0 255.255.255.0 fallback-lookup vrf source 

ip mroute vrf receiver 1.1.1.1 255.255.255.255 fallback-lookup vrf source 

With this, RPF check will be successful.

ASR1002-1#show ip rpf vrf receiver 1.1.1.1
RPF information for ? (1.1.1.1)
RPF interface: Loopback1
RPF neighbor: ? (1.1.1.1) - directly connected
RPF route/mask: 1.1.1.1/32
RPF type: multicast (connected)
Doing distance-preferred lookups across tables
Using Extranet RPF Rule: Static Fallback Lookup, RPF VRF: source
RPF topology: ipv4 multicast base

ASR1002-1#show ip rpf vrf receiver 10.1.1.1
RPF information for ? (10.1.1.1)
RPF interface: GigabitEthernet0/0/0
RPF neighbor: ? (10.1.1.1) - directly connected
RPF route/mask: 10.1.1.0/24
RPF type: multicast (connected)
Doing distance-preferred lookups across tables
Using Extranet RPF Rule: Static Fallback Lookup, RPF VRF: source
RPF topology: ipv4 multicast base

However, you can use either the RPF select or the fallback lookup command, both eventually fulfil our purpose.

Troubleshoot

There is currently no specific troubleshooting information available for this configuration.