[c-nsp] Nexus 7K - Multicast Question

Sat Oct 1 20:34:47 EDT 2011

Interface e1/27 on n7k12 appears to be connected 
to g2/2 on the 6500. I rest my case. ;)

Tim

At 12:40 PM 10/1/2011, Antonio Soares contended:
>Hello Tim,
>
>Very simple setup:
>
>N7K11===CAT6500===N7K12
>
>The RP is the CAT6500. The relevant configs bellow:
>
>CAT6500 (The RP):
>
>ip multicast-routing
>!
>interface Loopback0
>ip address 3.3.3.3 255.255.255.255
>ip pim sparse-mode
>!
>interface GigabitEthernet2/1
>ip address 10.12.1.2 255.255.255.0
>ip pim sparse-mode
>!
>interface GigabitEthernet2/2
>ip address 10.12.2.2 255.255.255.0
>ip pim sparse-mode
>no ip mroute-cache
>!
>ip pim rp-address 3.3.3.3
>!
>
>N7K11 (The source):
>
>feature ospf
>feature pim
>
>interface Ethernet1/27
>   ip address 10.12.1.1/24
>   ip router ospf 1 area 0.0.0.0
>   ip pim sparse-mode
>   no shutdown
>
>ip pim rp-address 3.3.3.3 group-list 224.0.0.0/4
>ip pim ssm range 232.0.0.0/8
>
>N7K12 (The destination)
>
>feature ospf
>feature pim
>
>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
>
>ip pim rp-address 3.3.3.3 group-list 224.0.0.0/4
>ip pim ssm range 232.0.0.0/8
>
>It works if the ip igmp join is moved to the loopback interface on the N7K12.
>
>
>Thanks.
>
>Regards,
>
>Antonio Soares, CCIE #18473 (R&S/SP)
><mailto:amsoares at netcabo.pt>amsoares at netcabo.pt
>http://www.ccie18473.net
>
>
>From: Tim Stevenson [mailto:tstevens at cisco.com]
>Sent: sábado, 1 de Outubro de 2011 16:06
>To: Antonio Soares; Phil Mayers; cisco-nsp at puck.nether.net
>Subject: Re: [c-nsp] Nexus 7K - Multicast Question
>
>Hi Antonio,
>
>Can you please describe the exact topology here? 
>Which interfaces you're using, what they're connected to, and where is the RP?
>
>One thing to be aware of with NXOS is that 
>things only show up in sh ip mroute if the 
>client protocol/process (eg IGMP in this case) 
>has reason to feed them there. sh ip mroute is 
>basically looking at the MRIB view of the world and nothing else.
>
>WRT the ip igmp join-group command, it does two 
>things: one is it causes that interface to send 
>IGMP joins for that group out that interface as 
>if it were a host. The other is that, if the 
>router is PIM DR on that interface, it feeds the 
>*G & the OIF to the MRIB. It's only at that 
>point you'll see the entry in sh ip mroute. 
>Otherwise, you'll only see it in the IGMP group 
>membership table, ie, sh ip igmp group.
>
>My guess here is you're not DR on this 
>interface, so I assume there's another router on 
>the segment that IS the DR. If you check the 
>mrouting there I suspect you'll see the *G entry 
>joined to the RPT (driven by the IGMP joins sent 
>on that segment from the router w/the join-group command).
>
>WRT the loopback "working", what you're seeing 
>is that this router is now the only means by 
>which to reach that 'network segment' (ie, it's 
>obviously going to be DR on its own loopback) so 
>it will report the *G & OIF to the MRIB and then 
>you'll see the entry in sh ip mroute.
>
>Hope that helps,
>Tim
>
>
>At 03:24 AM 10/1/2011, Antonio Soares contended:
>
>
>This is lab environment, I'm just testing basic multicast features with
>nexus.
>
>The command reference says the following:
>
>"When you enter this command, the traffic generated is handled by the device
>CPU, not the hardware."
>
><http://www.cisco.com/en/US/docs/switches/datacenter/sw/5_x/nx-os/multicast/c>http://www.cisco.com/en/US/docs/switches/datacenter/sw/5_x/nx-os/multicast/c 
>
>ommand/reference/mcr_cmds_i.html#wp1230243
>
>The "ip igmp static-group" was replaced by the command:
>
>ip igmp static-oif
>
><http://www.cisco.com/en/US/docs/switches/datacenter/sw/5_x/nx-os/multicast/c>http://www.cisco.com/en/US/docs/switches/datacenter/sw/5_x/nx-os/multicast/c 
>
>ommand/reference/mcr_cmds_i.html#wp1034808
>
>When I have the igmp joing on the physical interface, the (*,G) entry is
>created then it disappears. But I see the (*,G) entry on the RP and I
>verified that the traffic is actually sent to the nexus.
>
>
>Thanks.
>
>Regards,
>
>Antonio Soares, CCIE #18473 (R&S/SP)
>amsoares at netcabo.pt
><http://www.ccie18473.net>http://www.ccie18473.net
>
>
>-----Original Message-----
>From: cisco-nsp-bounces at puck.nether.net
>[ mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Phil Mayers
>Sent: sábado, 1 de Outubro de 2011 10:49
>To: cisco-nsp at puck.nether.net
>Subject: Re: [c-nsp] Nexus 7K - Multicast Question
>
>On 10/01/2011 01:31 AM, Antonio Soares wrote:
> > 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 ?
>
>"ip igmp join-group" is a CPU command; it makes the CPU join the group
>and receive the packets. I imagine this might not work on a hardware
>platform, with an interface which will be processed in hardware.
>
>Are you sure you don't want "ip igmp static-group"?
>
>What's your use case?
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>
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>
>
>
>Tim Stevenson, tstevens at cisco.com
>Routing & Switching CCIE #5561
>Distinguished Technical Marketing Engineer, Cisco Nexus 7000
>Cisco - <http://www.cisco.com/>http://www.cisco.com
>IP Phone: 408-526-6759
>********************************************************
>The contents of this message may be *Cisco Confidential*
>and are intended for the specified recipients only.

Tim Stevenson, tstevens at cisco.com
Routing & Switching CCIE #5561
Distinguished Technical Marketing Engineer, Cisco Nexus 7000
Cisco - http://www.cisco.com
IP Phone: 408-526-6759
********************************************************
The contents of this message may be *Cisco Confidential*
and are intended for the specified recipients only.