Multicast from VPC orphan ports doesn't work in some cases - N5K's & 6509E VSS - please help !

[Shlomy Maron]

I'd like to consult with you with an issue I've been encountered over our Production environment.

We have 6509E VSS Core Switch, running EIGRP.

There are 2 N5K's, that run VPC all of the vlans behind the Nexus, and they are the L3 termination point (interface Vlan is located over the N5K's).

For uplinks the each N5K has dedicated L3 interface running EIGRP, and connected to the same VLAN, and there is a dedicated physical link between them for backup.

Issue is this:

The Listener relays behind the 6509E VSS Core switch.

When Sender B is sending multicast traffic – everything working as it should and the Listener is getting the traffic.

When Sender A is sending the traffic – the traffic does not reach the Listener and its "stuck" over N5K-1.

In order to resolve this issue I've applied the command "ip multicast multipath" on the 6509E VSS – because the RPF points to the highest IP address of the neighbor which is N5K-2 10.62.252.17.

So far so good, but now – I can't get multicast streams from Sender B.

Would you mind to help me and tell me what am I missing ?

Why the 6509E sends PIM JOIN only towards one of the N5K's even after I apply the command "ip multicast multipath" ?

Why isn't N5K-2 sends the multicast traffic from Sender A when the command "ip multicast multipath" is not applied ? (after all the VPC Secondary should always send the Multicast stream from the orphan port towards the VPC Primary)

What am I missing ?

Topology:

[Jon Marshall]

Is a vPC used to connect the N5Ks to the 6500 ?

Jon

[Shlomy Maron]

Hi Jon,

VLAN 112 (where the senders are connected) is a vPC VLAN.

while VLAN 252 is not configured as a vlan over the N5K's and it is not VPC vlan.

It is a Vlan (and interface Vlan) on the Catalyst 6500 to have the ability to connect both N5K's to the same Subnet.

Yet the N5K's uplink is L3 Interface.

[Jon Marshall]

I don't have any direct experience with Nexus but I think that explains the first issue.

Are both N5ks RPs and what version of PIM are you using ?

Because vlan 252 is not extended between the N5Ks when A starts transmitting N5K2 never sees the traffic but N5K2 is the one that received the PIM join from the 6500.

Note I'm not saying to simply extend the vlan because that depends on a lot of other things but I think that is why you are not seeing the traffic on the receiver.

Jon

[Shlomy Maron]

Jon, thanks for your help !

The RP is a router located behind the 6500.

both N5K's uplinks are connected to a Catalyst 4500X (L2 Switch) on the same VLAN (252).

I'm using PIM SM - and on VLAN 252 the 6500 is the DR.

[Jon Marshall]

Sorry you have lost me here.

The RP is a router behind the 6500.

Does that router have any connections to the N5Ks ?

And where do the 4500s come into the picture ?

Are you saying there is a L2 path for vlan 252 between the N5Ks, it is just via another switch.

If so is that connection a vPC ?

Jon

[Shlomy Maron]

The RP, is just a router, reachable via EIGRP to the N5K's, and it located behind the 6500.

the RP has the registered value of the streams - as I mentioned I am able to get the traffic but I can get only traffic from one orphan port (depending on the configuration of multicast multipath).

the L2 path of Vlan 252 is not VPC , the 4500 switch is the L2 path between the N5K's and the 6500 switch. 

as shown in the photo there is a VLAN 252 (shared segment) connecting the L3 interfaces of each N5K ETH1/1 to the interface vlan of the 6500.

[Jon Marshall]

Sorry, my mistake about vlan 252, ignore my first response.

I meant to ask about vlan 112, is that vlan extended between the N5Ks ?

Are the senders connected to the N5Ks and in that vlan directly attached ie. you mentioned orphan ports ?

Jon

[Shlomy Maron]

I've uploaded better topology and better explanation.

Vlan 112 is a VPC VLan, and each Sender is connected as an Orphan port - in each case on a different N5K.

[Reza Sharifi]

Question related to your physical topology;

Are both 6500 switches (VSS) connected to both 5ks?

The drawing shows one connection to each 5k and one connection to VSS.

I am not saying what you have in place is not correct, but they way I have set this up in the past is with /30s and Portchannels.

2 connections from each 5ks (one to one 6500 and the other one to the other 6500 (total 4 connections).

the connections from the first 5k in one Portchannel with a /30 and the connections from the second 5k in a different Portchannel with /30.

HTH

[Shlomy Maron]

apperently there is a missing command.

since we have Multicast being sent on an orphan port the command on both N5K's is needed- 

vpc bind-vrf default vlan 3000

to allow multicast to go via the second N5K.

[Shlomy Maron]

let me write the issue again -

Vlan 112 is a VPC Vlan, there are 2 multicast senders in this VLAN , each of them connected to a different N5K as an orphan ports.

By default I can receive the traffic only from Sender B.

After looking around I've noticed that applying the command "ip multicast multipath" on the 6509E VSS made it possible to receive the multicast traffic from Sender A.

YET – the problem is that now, while I can receive the traffic from sender A – I'm not able to receive multicast traffic from Sender B anymore.

If I remove the command "ip multicast multipath" – I can receive the traffic from Sender B but not from sender A.

VLAN 252 is a shared segment between the N5K's and the 6509E VSS – yet it is not a VPC VLAN, and it is not a vlan over the N5Ks – the N5K use ETH1/1 as no switchport L3 interface.

[Jon Marshall]

Thanks for the clarification.

If we concentrate on the original issue what does a "sh ip mroute" (or equivalent for Nexus) show on both N5Ks when sender A is transmitting and the receiver has registered an interest.

And what does the same output show when sender B is transmitting ?

Jon

[ulrickfr2001]

Hi guys,

I am facing much the same issue but the receiver is an orphan port and the sender is connected to a vPC vlan. The description below.

- RP IP address : 172.19.1.241

 - Receiver IP address : 172.18.66.1

 - There is vPC configured between N5Ks and N7Ks with Vlan tag

 - The interconnections are configured with HSRP (for redundancy)

 - When the IP source address is 172.19.35.5, the stream on multicast group 239.225.1.3 is received but the stream on multicast group 239.225.1.4 is not.

 - When the IP source address is 172.19.35.5 the stream on multicast group 239.225.1.4 is received but the stream on multicast group 239.225.1.3 is not.

Can someone help ?