[c-nsp] Nexus 7K - Multicast Question

[Antonio Soares]

Hello group,

Anyone knows why the "ip igmp join-group" does not work on a physical
interface but it works fine on a loopback interface ?

Here's what I have with the physical interface and a ping multicast from
another nexus doesn't get replies:

-------------------------------------------------------
N7K12# sh ip mroute 
IP Multicast Routing Table for VRF "default"

(*, 232.0.0.0/8), uptime: 00:53:43, pim ip 
  Incoming interface: Null, RPF nbr: 0.0.0.0
  Outgoing interface list: (count: 0)

N7K12# 
N7K12# sh runn int e1/27

!Command: show running-config interface Ethernet1/27
!Time: Sat Oct  1 05:36:39 2011

version 5.1(4)

interface Ethernet1/27
  ip address 10.12.2.1/24
  ip router ospf 1 area 0.0.0.0
  ip pim sparse-mode
  ip igmp join-group 239.1.2.3
  no shutdown

N7K12#
-------------------------------------------------------

When the join is moved to a loopback interface everything works fine:

-------------------------------------------------------
N7K12# sh ip mroute
IP Multicast Routing Table for VRF "default"

(*, 232.0.0.0/8), uptime: 00:57:33, pim ip 
  Incoming interface: Null, RPF nbr: 0.0.0.0
  Outgoing interface list: (count: 0)

(*, 239.1.2.3/32), uptime: 00:00:10, igmp pim ip 
  Incoming interface: Ethernet1/27, RPF nbr: 10.12.2.2
  Outgoing interface list: (count: 1)
    loopback0, uptime: 00:00:10, igmp

(10.12.1.1/32, 239.1.2.3/32), uptime: 00:00:09, ip mrib pim 
  Incoming interface: Ethernet1/27, RPF nbr: 10.12.2.2
  Outgoing interface list: (count: 1)
    loopback0, uptime: 00:00:09, mrib

N7K12# 
N7K12# sh runn int lo0

!Command: show running-config interface loopback0
!Time: Sat Oct  1 05:40:36 2011

version 5.1(4)

interface loopback0
  ip address 2.2.2.2/32
  ip router ospf 1 area 0.0.0.0
  ip pim sparse-mode
  ip igmp join-group 239.1.2.3

N7K12#
-------------------------------------------------------

If I configure again the physical interface, I see this during a couple of
seconds then it goes away:

-------------------------------------------------------
N7K12(config-if)# sh ip mroute
IP Multicast Routing Table for VRF "default"

(*, 232.0.0.0/8), uptime: 01:00:09, pim ip 
  Incoming interface: Null, RPF nbr: 0.0.0.0
  Outgoing interface list: (count: 0)

(*, 239.1.2.3/32), uptime: 00:02:46, pim ip 
  Incoming interface: Ethernet1/27, RPF nbr: 10.12.2.2
  Outgoing interface list: (count: 0)

(10.12.1.1/32, 239.1.2.3/32), uptime: 00:02:46, ip mrib pim 
  Incoming interface: Ethernet1/27, RPF nbr: 10.12.2.2
  Outgoing interface list: (count: 0)

N7K12(config-if)#
-------------------------------------------------------

So the OIL count is 0, that's why it doesn't work. Is this normal behavior
with NXOS ? I never saw this with IOS.


Thanks.

Regards,

Antonio Soares, CCIE #18473 (R&S/SP)
amsoares at netcabo.pt
http://www.ccie18473.net