topic Re: SPBM MULTICAST BETWEEN TWO FABRIC in ExtremeSwitching (VSP/Fabric Engine)

SPBM MULTICAST BETWEEN TWO FABRIC

EF — Mon, 09 Jun 2025 14:16:59 GMT

Hi Team,

I want to configure multicast between two fabric linked by legacy trunk of VLANs, they are two different fabrics not a multiarea fabric.

It´s multicast at L2, igmp snooping , the senders and receivers will be in both fabric distributed aleatory.

Is this topology supported? Any tips to configure it?

For ip igmp snooping inside a single fabric I configure:

At global level:

router isis
spbm 1 multicast enable

At VLAN level:

interface vlan XX
ip igmp proxy
ip igmp snooping

But I dont know how to inyect multicast traffic between them.

Regards

Re: SPBM MULTICAST BETWEEN TWO FABRIC

WillyHe — Tue, 10 Jun 2025 20:16:14 GMT

Hi EF,

A quick and simple way is to statically forward all MCAST's from Fabric 1 to Fabric 2 and from Fabric 2 to Fabric 1, to that you configure static-group membership in the vlan interface towards port(s).
You can specify group address per group address to be forwarded or group address ranges to one or more ports.
Disadvantage is that existing streams are always forwarded over the link.

interface Vlan 1000
ip igmp static-group 239.0.0.1 239.0.0.1 1/9,1/11 static
ip igmp static-group 239.0.0.5 239.0.0.8 1/11 static
exit

regards
WillyHe

Re: SPBM MULTICAST BETWEEN TWO FABRIC

EF — Fri, 13 Jun 2025 06:38:57 GMT

Hi WillyHe,

Thanks for your tips for Im not able configure it, this is my lab:

But SW MAD1 doenst "see" sender or recivers, and if I try configure the statis groups under int vlan (Vlan200);

Thanks in advance for your answers.

Cheers!!

Re: SPBM MULTICAST BETWEEN TWO FABRIC

jerrygen — Sun, 22 Jun 2025 11:26:05 GMT

Hi EF,

Yes, it’s possible, but since they’re separate fabrics linked by legacy VLAN trunks, you’ll likely need multicast routing or IGMP proxying between the cores. IGMP snooping alone won’t forward across fabrics—consider using PIM or a Layer 3 multicast gateway between them.

Regards

Re: SPBM MULTICAST BETWEEN TWO FABRIC

EF — Wed, 25 Jun 2025 06:53:06 GMT

Hi,

yes it works with statics groups, I was using the command incorrectly, GTAC give the solution, for example for 5 groups:

int vlan 200
ip igmp static-group 234.5.6.10 234.5.6.10 1/27 static
ip igmp static-group 234.5.6.11 234.5.6.11 1/27 static
ip igmp static-group 234.5.6.12 234.5.6.12 1/27 static
ip igmp static-group 234.5.6.13 234.5.6.13 1/27 static
ip igmp static-group 234.5.6.14 234.5.6.14 1/27 static
exit

Regards

Re: SPBM MULTICAST BETWEEN TWO FABRIC

WillyHe — Wed, 25 Jun 2025 07:54:32 GMT

Hello EF,

The disadvantage of the static solution is that ALL MCAST traffic (that is statically configured) is forwarded over the trunk to the other fabric and consuming bandwidth, also for which there is no receiver on the other side.

When this bandwidth consumption is a problem then you must setup a SPBM-PIM Gateway between the fabrics.

regards
WillyHe

Re: SPBM MULTICAST BETWEEN TWO FABRIC

EF — Wed, 25 Jun 2025 08:16:47 GMT

Thanks WillyHe,

but one question, and sorry in advance for my lack of knowledge. I understand PIM is used for multicast in L3 topologies and in this solution all members (senders and recivers) are in the same VLAN, or SPBM-PIM Gateway can acts in L2 topology?

Regards

Re: SPBM MULTICAST BETWEEN TWO FABRIC

EF — Wed, 25 Jun 2025 08:30:16 GMT

Q A: SPBM Multicast : What is PIM Gateway ? | Extreme Portal

Re: SPBM MULTICAST BETWEEN TWO FABRIC

WillyHe — Wed, 25 Jun 2025 15:50:14 GMT

What you need to dynamically connect MCAST between two SPBM domains https://extreme-networks.my.site.com/ExtrArticleDetail?an=000096922

regards
WillyHe