Configure Multicast Service Reflection on Nexus 3000

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Updated:July 26, 2023

Document ID:218187

Bias-Free Language

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Introduction

This document describes how to configure and verify the Service Reflection feature on the Cisco Nexus 3000 (regular mode) series switches.

Prerequisites

Requirements

General recommendations that you have knowledge of these topics:

Protocol Independent Multicast (PIM)
Open Shortest Path First (OSPF)
Network Address Translation (NAT)
Internet Group Management Protocol (IGMP)

Components Used

The information in this document is based on these software and hardware versions:

Sw1#	N9K-C93180YC-FX	NXOS: version 9.3(5)
Sw2#	N3K-C3548P-XL	NXOS: version 7.0(3)I7(9)
Sw3#	N3K-C3172TQ-10GT	NXOS: version 7.0(3)I7(9)

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.

Background Information

Supported Cisco Nexus 3k Platforms

The multicast service reflection feature is supported only on Cisco Nexus 3548-X platforms from Release 7.0(3)I7(2).

Supported Methods of Service Reflection

Regular Mode Multicast NAT

In regular mode, the packets incoming as the S1, G1 interfaces are translated to S2, G2 interfaces and the destination Media Access Control (MAC) address of the outgoing packet is translated as the multicast MAC address of the G2 interface (for example, the translated group).

Fast-pass and Fast-pass with No-rewrite Multicast NAT

In fast-pass mode, the S1, G1 interfaces are translated to S2, G2 interfaces and the destination MAC address of the outgoing packet has the multicast MAC address that corresponds to the G1 interface (for example, the MAC address of the pre-translated group).

Configure

Topology

Native Group: 239.194.169.1 (G1)

Translated Group: 233.193.40.196 (G2)

Original Source: 10.11.11.1 (S1)

Translated Source: 172.16.0.1. (S2)

Configuration

Switch 1 Config (Sender)

SW1# show run int eth1/47

interface Ethernet1/47
no switchport
ip address 10.11.11.1/24
ip ospf network point-to-point
ip router ospf 1 area 0.0.0.0
ip pim sparse-mode


SW1# show run ospf
feature ospf
router ospf 1
router-id 192.168.1.1
interface Ethernet1/47
ip ospf network point-to-point
ip router ospf 1 area 0.0.0.0

SW1# show run pim
feature pim
ip pim rp-address 10.10.10.10 group-list 239.194.169.1/32
ip pim ssm range 232.0.0.0/8
interface Ethernet1/47
ip pim sparse-mode

Switch 2 Config (Translator)



SW2# show run int eth 1/23,eth1/47
interface Ethernet1/23
no switchport
ip address 10.0.0.1/24
ip ospf network point-to-point
ip router ospf 1 area 0.0.0.0
ip pim sparse-mode
no shutdown

interface Ethernet1/47
  no switchport
  ip address 10.11.11.2/24
  ip ospf network point-to-point
  ip router ospf 1 area 0.0.0.0
  ip pim sparse-mode
  no shutdown


SW2# show run int lo0,lo411
interface loopback0
ip address 10.10.10.10/32
ip router ospf 1 area 0.0.0.0
ip pim sparse-mode

interface loopback411
ip address 172.16.0.1/32
ip router ospf 1 area 0.0.0.0
ip pim sparse-mode
ip igmp join-group 239.194.169.1


SW2# show run ospf
feature ospf
router ospf 1
router-id 192.168.1.2

interface loopback0
ip router ospf 1 area 0.0.0.0

interface loopback411
ip router ospf 1 area 0.0.0.0

interface Ethernet1/23
ip ospf network point-to-point
ip router ospf 1 area 0.0.0.0

interface Ethernet1/47
ip ospf network point-to-point
ip router ospf 1 area 0.0.0.0

SW2# show run pim
feature pim

ip pim rp-address 10.10.10.10 group-list 239.194.169.1/32
ip pim rp-address 172.16.0.1 group-list 233.193.40.196/32
ip pim ssm range 232.0.0.0/8

interface loopback0
ip pim sparse-mode

interface loopback411
ip pim sparse-mode

interface Ethernet1/23
ip pim sparse-mode

interface Ethernet1/47
ip pim sparse-mode

ip service-reflect mode regular
ip service-reflect destination 239.194.169.1 to 233.193.40.196 mask-len 32 source 172.16.0.1
hardware profile multicast service-reflect port 7

Switch 3 Config (Receiver)

SW3# show run int eth 1/24
interface Ethernet1/24
ip address 10.0.0.2/24
ip ospf network point-to-point
ip router ospf 1 area 0.0.0.0
ip pim sparse-mode
ip igmp join-group 233.193.40.196
no shutdown


SW3# show run ospf
feature ospf
router ospf 1
router-id 192.168.1.3

interface Ethernet1/24
ip ospf network point-to-point
ip router ospf 1 area 0.0.0.0


SW3# show run pim

feature pim
ip pim rp-address 172.16.0.1 group-list 233.193.40.196/32
ip pim ssm range 232.0.0.0/8

interface Ethernet1/24
ip pim sparse-mode

Verify

Use this section in order to confirm that your configuration works properly.

Verify Service Reflection Feature

Switch 1 Verification

SW1# show ip mroute
IP Multicast Routing Table for VRF "default"

(*, 232.0.0.0/8), uptime: 3w6d, pim ip
  Incoming interface: Null, RPF nbr: 0.0.0.0
  Outgoing interface list: (count: 0)

(10.11.11.1/32, 239.194.169.1/32), uptime: 00:06:57, pim ip
  Incoming interface: Ethernet1/47, RPF nbr: 10.11.11.1
  Outgoing interface list: (count: 1)
  Ethernet1/47, uptime: 00:06:57, pim, (RPF)

Switch 2 Verification


SW2# show ip mroute
IP Multicast Routing Table for VRF "default"

(*, 232.0.0.0/8), uptime: 00:04:39, pim ip
  Incoming interface: Null, RPF nbr: 0.0.0.0
  Outgoing interface list: (count: 0)

(*, 233.193.40.196/32), uptime: 00:04:11, pim ip
  Incoming interface: loopback411, RPF nbr: 172.16.0.1  <-- Translation (ingress) Loopback interface
  Outgoing interface list: (count: 1)
  Ethernet1/23, uptime: 00:03:59, pim    <-- Egress interface for S2,G2 


(172.16.0.1/32, 233.193.40.196/32), uptime: 00:00:15, ip mrib pim
  Incoming interface: loopback411, RPF nbr: 172.16.0.1
  Outgoing interface list: (count: 1)
  Ethernet1/23, uptime: 00:00:15, pim

(*, 239.194.169.1/32), uptime: 00:04:34, static pim ip  <-- (The NAT router would pull the traffic by using a (*,G) join on loopback )
  Incoming interface: loopback0, RPF nbr: 10.10.10.10
  Outgoing interface list: (count: 1)
 loopback411, uptime: 00:04:34, static    <-- Translation (egress) Loopback interface 

(10.11.11.1/32, 239.194.169.1/32), uptime: 00:00:17, ip mrib pim
  Incoming interface: Ethernet1/47, RPF nbr: 10.11.11.1, internal     <-- Ingress interface for S1,G1 
  Outgoing interface list: (count: 1)
  loopback411, uptime: 00:00:17, mrib



SW2# show ip mroute sr   <-- (Only SR nat routes) 
IP Multicast Routing Table for VRF "default"

(*, 239.194.169.1/32), uptime: 00:09:29, static pim ip
    NAT Mode: Ingress
    NAT Route Type: Pre
    Incoming interface: loopback0, RPF nbr: 10.10.10.10
    Translation list: (count: 1)
    SR: (172.16.0.1, 233.193.40.196)

(10.11.11.1/32, 239.194.169.1/32), uptime: 00:05:12, ip mrib pim
    NAT Mode: Ingress
    NAT Route Type: Pre
    Incoming interface: Ethernet1/47, RPF nbr: 10.11.11.1, internal
    Translation list: (count: 1)
    SR: (172.16.0.1, 233.193.40.196)

Switch 3 Verification

SW3# show ip mroute
IP Multicast Routing Table for VRF "default"
(*, 232.0.0.0/8), uptime: 02:45:09, pim ip
Incoming interface: Null, RPF nbr: 0.0.0.0
Outgoing interface list: (count: 0)

(*, 233.193.40.196/32), uptime: 01:47:02, ip pim igmp
Incoming interface: Ethernet1/24, RPF nbr: 10.0.0.1
Outgoing interface list: (count: 1)
Ethernet1/24, uptime: 01:43:27, igmp, (RPF)

(172.16.0.1/32, 233.193.40.196/32), uptime: 00:02:59, ip mrib pim
Incoming interface: Ethernet1/24, RPF nbr: 10.0.0.1
Outgoing interface list: (count: 1)
Ethernet1/24, uptime: 00:02:59, mrib, (RPF)

Troubleshoot

This section provides information you can use in order to troubleshoot your configuration.

If S2 and G2 do not get created or the user faces random translation issues, you can check these points:

1. Once the traffic is received (pre-translated), post-translated entries are created based on pkt punted in mcastfwd.

2. If you do not see pkt punted in mcastfwd, you can check if you get the requested traffic on the ingress interface via ACL.

3 If you see increased counters in ACL, check same traffic hits CPU via ethanalyzer.

4 Can also check translation in MRIB event-history:


SW2# show system  internal  mfwd ip mroute  --> Packets Punted in Mcast Forwarding. 
MCASTFWD Multicast Routing Table for VRF "default"
(0.0.0.0/0, 232.0.0.0/8)
  Software switched packets: 0, bytes: 0
  RPF fail packets: 0, bytes: 0
(0.0.0.0/0, 233.193.40.196/32)
  Software switched packets: 1, bytes: 84
  RPF fail packets: 0, bytes: 0
(172.16.0.1/32, 233.193.40.196/32), data-alive
  Software switched packets: 1, bytes: 84
  RPF fail packets: 8, bytes: 672
(0.0.0.0/0, 239.194.169.1/32)
  Software switched packets: 1, bytes: 84
RPF fail packets: 0, bytes: 0
(10.11.11.1/32, 239.194.169.1/32), data-alive
Software switched packets: 10, bytes: 840
RPF fail packets: 0, bytes: 0


SW2# show ip access-lists test
IP access list test
        statistics per-entry
        10 permit ip any 239.194.169.1/32 [match=105] <-- Intrested traffic hitting ingress interface 
        20 permit ip any any [match=11]       

interface Ethernet1/47
  no switchport
  ip access-group test in  <-- ACL applied on ingress interface 
  ip address 10.11.11.2/24
  ip ospf network point-to-point
  ip router ospf 1 area 0.0.0.0
  ip pim sparse-mode
  no shutdown


SW2# ethanalyzer loca int inband display-filter "ip.addr == 239.194.169.1" limit-captured-frames 0  --> Confirm (S1,G1) seen on CPU
Capturing on inband
wireshark-cisco-mtc-dissector: ethertype=0xde09, devicetype=0x0
2022-09-18 04:21:37.840227 10.11.11.1 -> 239.194.169.1 ICMP Echo (ping) request
2022-09-18 04:21:37.841275 10.11.11.1 -> 239.194.169.1 ICMP Echo (ping) request
2022-09-18 04:21:37.860153 10.11.11.1 -> 239.194.169.1 ICMP Echo (ping) request
2022-09-18 04:21:37.861199 10.11.11.1 -> 239.194.169.1 ICMP Echo (ping) request
2022-09-18 04:21:37.880072 10.11.11.1 -> 239.194.169.1 ICMP Echo (ping) request
2022-09-18 04:21:37.881113 10.11.11.1 -> 239.194.169.1 ICMP Echo (ping) request


SW2# ethanalyzer local  interface  inband capture-filter  "host 172.16.0.1" limit-captured-frames 0 --> Confirm (S2,G2) seen on CPU
Capturing on inband
wireshark-cisco-mtc-dissector: ethertype=0xde09, devicetype=0x0
2022-09-18 03:12:51.423484 172.16.0.1 -> 233.193.40.196 ICMP Echo (ping) request
2022-09-18 03:12:51.423978 10.0.0.2 -> 172.16.0.1 ICMP Echo (ping) reply
2022-09-18 03:12:53.425754 172.16.0.1 -> 233.193.40.196 ICMP Echo (ping) request
2022-09-18 03:12:53.425761 10.0.0.2 -> 172.16.0.1 ICMP Echo (ping) reply
2022-09-18 03:12:55.426719 172.16.0.1 -> 233.193.40.196 ICMP Echo (ping) request
2022-09-18 03:12:55.426726 10.0.0.2 -> 172.16.0.1 ICMP Echo (ping) reply
2022-09-18 03:12:57.428669 172.16.0.1 -> 233.193.40.196 ICMP Echo (ping) request
2022-09-18 03:12:57.429175 10.0.0.2 -> 172.16.0.1 ICMP Echo (ping) reply
2022-09-18 03:12:59.429890 172.16.0.1 -> 233.193.40.196 ICMP Echo (ping) request
2022-09-18 03:12:59.430386 10.0.0.2 -> 172.16.0.1 ICMP Echo (ping) reply
10 packets captured


SW2# show ip pim event-history  mrib --> Event history to confirm that the translation is being done
2022 Sep 18 04:28:39.970688: E_DEBUG    pim [19433]:  Sending ack: xid: 0xeeee00d2
2022 Sep 18 04:28:39.970255: E_DEBUG    pim [19433]:  MRIB Join notify for (10.11.11.1/32, 239.194.169.1/32)
2022 Sep 18 04:28:39.968875: E_DEBUG    pim [19433]:  MRIB sr route type notif for (10.11.11.1/32, 239.194.169.1/32) : 1
2022 Sep 18 04:28:39.968859: E_DEBUG    pim [19433]:  pim_process_mrib_rpf_notify: MRIB RPF notify for (10.11.11.1/32, 239.194.169.1/32), old RPF info: 10.11.11.1 (Ethernet1/47), new RPF info: 10.11.11.1 (Ethernet1/47). LISP source RLOC address
: 0.0.0.0, route-type 1
2022 Sep 18 04:28:39.968307: E_DEBUG    pim [19433]:  Copied the flags from MRIB for route (10.11.11.1/32, 239.194.169.1/32), (before/after): att F/F, sta F/F, z-oifs T/F, ext F/F, fabric F/F, fabric_src: F/F mofrr F/F
2022 Sep 18 04:28:39.968301: E_DEBUG    pim [19433]:  MRIB Join notify for (10.11.11.1/32, 239.194.169.1/32)
2022 Sep 18 04:28:39.968294: E_DEBUG    pim [19433]: Received a notify message from MRIB xid: 0xeeee00cf for 1 mroutes
2022 Sep 18 04:28:35.904652: E_DEBUG    pim [19433]:  Sending ack: xid: 0xeeee00cc
2022 Sep 18 04:28:35.904625: E_DEBUG    pim [19433]:  pim_process_mrib_rpf_notify: MRIB RPF notify for (172.16.0.1/32, 233.193.40.196/32), old RPF info: 172.16.0.1 (loopback411), new RPF info: 172.16.0.1 (loopback411). LISP sourc
e RLOC address: 0.0.0.0, route-type 0
2022 Sep 18 04:28:35.904484: E_DEBUG    pim [19433]:  pim_process_mrib_rpf_notify: After copying the values for route (0.0.0.0/32, 233.193.40.196/32) we got RPF info: 172.16.0.1 (loopback411). LISP source RLOC address: 0.0.0.0, route-t
ype 0
2022 Sep 18 04:28:35.904476: E_DEBUG    pim [19433]:  pim_process_mrib_rpf_notify: MRIB RPF notify for (0.0.0.0/32, 233.193.40.196/32), old RPF info: 0.0.0.0 ((null)), new RPF info: 172.16.0.1 (loopback411). LISP source RLOC address: 0
.0.0.0, route-type 0
2022 Sep 18 04:28:35.904400: E_DEBUG    pim [19433]:  MRIB Join notify for (172.16.0.1/32, 233.193.40.196/32)
2022 Sep 18 04:28:35.904343: E_DEBUG    pim [19433]:  MRIB Join notify for (0.0.0.0/32, 233.193.40.196/32)
2022 Sep 18 04:27:49.862827: E_DEBUG    pim [19433]:  pim_process_mrib_rpf_notify: After copying the values for route (*, 239.194.169.1/32) we got RPF info: 10.10.10.10 (loopback0). LISP source RLOC address: 0.0.0.0, route-type 0
2022 Sep 18 04:27:49.862812: E_DEBUG    pim [19433]:  pim_process_mrib_rpf_notify: MRIB RPF notify for (*, 239.194.169.1/32), old RPF info: 0.0.0.0 ((null)), new RPF info: 10.10.10.10 (loopback0). LISP source RLOC address: 0.0.0.0, route-
type 0
2022 Sep 18 04:27:49.862798: E_DEBUG    pim [19433]:  MRIB Join notify for (*, 239.194.169.1/32)
2022 Sep 18 04:27:49.862795: E_DEBUG    pim [19433]:  MRIB Join notify for (172.16.0.1/32, 233.193.40.196/32)
2022 Sep 18 04:27:49.862789: E_DEBUG    pim [19433]:  MRIB Join notify for (0.0.0.0/32, 233.193.40.196/32)
2022 Sep 18 04:27:49.861870: E_DEBUG    pim [19433]:  Creating PIM route for (*, 239.194.169.1/32)
2022 Sep 18 04:27:49.861868: E_DEBUG    pim [19433]:  MRIB Join notify for (*, 239.194.169.1/32)

Summary

In Regular mode, traffic hits the original S, G entry in the first pass and recirculates due to Outgoing Interface List (OIFL) which has only the loopback port. In the second pass, it derives the destination MAC for the rewrite.
In the third pass, the multicast route lookup happens on the translated S, G and the packet is forwarded to the corresponding translated group OIFL ports.
Added static join on loopback to force the traffic to be received on the NAT box.
When first packet is received for (s1, g1), switch would program (s1,g1) with new SR flag (s1, g ---> s2 ,g2) .
The switch would use this metadata to do recircle of the packet and punt the packet for g2. Once (S2, G2) packet is punted to sup, FHR (first-hop router) functionality would be triggered on NAT box for s2,g2.
Once the traffic is received ie pre-translated and post-translated entries would be created based on pkt punted in mcastfwd.
If you don’t see the packet punted in mcastfwd for respective group, you can use the mentioned troubleshoot process to confirm if interested traffic hits the switch

Related Information

Cisco Technical Support & Downloads

Revision History

Revision	Publish Date	Comments
2.0	26-Jul-2023	Updated and republished.
1.0	21-Sep-2022	Initial Release

Contributed by Cisco Engineers

Deepak Keshwani
Cisco TAC Engineer

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