[c-nsp] Multicast in VRF

[Harivishnu Abhilash]

Just check if you have any IP options drops configured. It can drop the IGMP messages(havening Router alert),,

Ta

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Jan Gregor
Sent: Monday, March 19, 2018 10:23 PM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] Multicast in VRF

Hi guys,

I am stumped by a multicast issue on one of my 6500 switches running s72033-adventerprisek9-mz.151-2.SY11.bin code. Actually it is two 6500s in VSS, but it should not matter, correct me if I am wrong.

The topology is fairly simple, a source is connected to one VLAN on 6500, then the receiver is on another VLAN on the same 6500. Both VLANs are in the same VRF. Both VLANs are configured for PIM Sparse mode. 
Multicast routing is enabled for the VRF. Relevant config:
vrf definition TEST
  rd 65000:803
  !
  address-family ipv4
  exit-address-family
!
ip multicast-routing
ip multicast-routing vrf TEST
!
ip pim vrf TEST rp-address 10.0.0.1
!
interface Vlan803
  description SOURCE
  vrf forwarding TEST
  ip address 10.0.0.1 255.255.255.0
  ip pim sparse-mode
  arp timeout 300
!
interface Vlan804
  description RECEIVER
  vrf forwarding TEST
  ip address 192.168.2.1 255.255.255.0
  ip pim sparse-mode
  load-interval 30
  arp timeout 300

I see multicast routing entries in the mroute table for the VRF increasing:
sh ip mroute vrf TEST
...
Outgoing interface flags: H - Hardware switched, A - Assert winner
  Timers: Uptime/Expires
  Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.192.2.196), 00:24:57/stopped, RP 10.0.0.1, flags: SJC
   Incoming interface: Null, RPF nbr 0.0.0.0
   Outgoing interface list:
     Vlan804, Forward/Sparse, 00:24:57/00:02:40

(10.0.0.11, 239.192.2.196), 00:24:57/00:02:57, flags: T
   Incoming interface: Vlan803, RPF nbr 0.0.0.0, RPF-MFD
   Outgoing interface list:
     Vlan804, Forward/Sparse, 00:24:57/00:02:40, H

sh ip mroute vrf TEST count
IP Multicast Statistics
2 routes using 1102 bytes of memory
1 groups, 1.00 average sources per group Forwarding Counts: Pkt Count/Pkts per second/Avg Pkt Size/Kilobits per second Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)

Group: 239.192.2.196, Source count: 1, Packets forwarded: 1503, Packets
received: 1503
   RP-tree: Forwarding: 0/0/0/0, Other: 0/0/0
   Source: 10.0.0.11/32, Forwarding: 1503/1/84/0, Other: 1503/0/0

sh ip mroute vrf TEST count
IP Multicast Statistics
2 routes using 1102 bytes of memory
1 groups, 1.00 average sources per group Forwarding Counts: Pkt Count/Pkts per second/Avg Pkt Size/Kilobits per second Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)

Group: 239.192.2.196, Source count: 1, Packets forwarded: 1510, Packets
received: 1510
   RP-tree: Forwarding: 0/0/0/0, Other: 0/0/0
   Source: 10.0.0.11/32, Forwarding: 1510/1/84/0, Other: 1510/0/0

I am testing it by running ping on the source "ping -t 64 239.192.2.196". I see packets leaving the source as verified by tcpdump. 
However packets are not making it to the receiver as verified by tcpdump.

Funny thing is that when I clear the mroute table on the switch by issuing "clear ip mroute vrf TEST *" I receive EXACTLY ONE ping packet on the receiver, then again nothing:
20:17:02.576050 IP 10.0.0.11 > 239.192.2.196: ICMP echo request, id 11724, seq 625, length 64

Any pointers would be greatly appreciated.

Best regards,

Jan Gregor


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