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Multicast receiver not receiving mcast from sender on same vlan

mortonjes
Level 1
Level 1

I have a situation where I have multicast sender and receiver on the same physical switch on the same vlan.

The receiver is not able to join the senders mulitcase group. I do have IGMP snooping enabled and was hoping not to have to disable it. (Not that disabling would work either....)

One thing to note is on the upstream router (I'd call this the multicast router) I've configured sparse-mode and also built a GRE tunnel to get multicast to another location. Receivers at the remote location (On a different subnet) are able to receive all the senders mcast feeds! It seems to be isolated to the sender and receivers on the same subnet off the same switch that can't receive/join groups. Below is part of the config on the router. Nothing special off the switch.

Any help would be appreciated.

Switch: C7000 (inside an HP Blade server chassis)

Router: Cisco 7206

router config:

ip multicast-routing

ip dvmrp interoperability

interface Loopback1

description TUNNEL SOURCE TO XXX FOR MULTICAST

ip address 10.10.254.1 255.255.255.255

ip pim sparse-mode

!

interface Tunnel0

description MULTICAST TUNNEL TO XXX TUNNEL 0

ip address 10.10.253.1 255.255.255.252

ip pim sparse-mode

tunnel source Loopback1

tunnel destination 10.10.254.2

interface GigabitEthernet0/2

no ip address

ip pim sparse-mode

duplex auto

speed auto

media-type rj45

no negotiation auto

!

interface GigabitEthernet0/2.10

description *** LAN, MGMT VLAN ***

encapsulation dot1Q 10

ip address 10.10.0.1 255.255.255.0

ip pim sparse-mode

!

interface GigabitEthernet0/2.12

description *** LAN, SERVERS VLAN ***

encapsulation dot1Q 12

ip address 10.10.2.1 255.255.255.0

ip pim sparse-mode

!

ip pim rp-address 10.10.254.2

ip mroute 192.168.17.0 255.255.255.0 Tunnel0

ip mroute 10.10.254.2 255.255.255.255 Tunnel0

ip mroute 10.10.2.0 255.255.255.0 10.10.0.1

The receiver is 10.10.2.10 & 24 trying to recieve from any of groups 224.1.1.1, .2, or .3

show IP mroute:

(*, 224.1.1.1), 01:19:40/stopped, RP 10.10.254.2, flags: SJCF

Incoming interface: Tunnel0, RPF nbr 10.10.253.2, Mroute

Outgoing interface list:

GigabitEthernet0/2.12, Forward/Sparse, 01:08:26/00:02:20

(10.10.2.20, 224.1.1.1), 01:19:40/00:03:28, flags: FT

Incoming interface: GigabitEthernet0/2.12, RPF nbr 0.0.0.0, Registering (data-header)

Outgoing interface list:

Tunnel0, Forward/Sparse, 01:19:35/00:02:36

(*, 224.1.1.3), 01:19:36/stopped, RP 10.10.254.2, flags: SJCF

Incoming interface: Tunnel0, RPF nbr 10.10.253.2, Mroute

Outgoing interface list:

GigabitEthernet0/2.12, Forward/Sparse, 01:08:27/00:02:20

(10.10.2.20, 224.1.1.3), 01:15:31/00:02:59, flags: PFT

Incoming interface: GigabitEthernet0/2.12, RPF nbr 0.0.0.0, Registering (data-header)

Outgoing interface list: Null

(*, 224.1.1.2), 01:19:41/stopped, RP 10.10.254.2, flags: SJCF

Incoming interface: Tunnel0, RPF nbr 10.10.253.2, Mroute

Outgoing interface list:

GigabitEthernet0/2.12, Forward/Sparse, 01:08:26/00:02:19

(10.10.2.24, 224.1.1.2), 01:16:17/00:02:59, flags: PFT

Incoming interface: GigabitEthernet0/2.12, RPF nbr 0.0.0.0, Registering (data-header)

Outgoing interface list: Null

(*, 224.0.1.40), 01:19:43/00:02:19, RP 10.10.254.2, flags: SJCL

Incoming interface: Tunnel0, RPF nbr 10.10.253.2, Mroute

Outgoing interface list:

Loopback1, Forward/Sparse, 01:19:43/00:02:19

25 Replies 25

Peter Paluch
Cisco Employee
Cisco Employee

Hello,

If the multicast sender and receiver are on the same physical switch and on the same VLAN then the router should indeed not be necessary here.

Can you check and post the output of the "show ip igmp snooping group" of that switch? Also, on which ports are the sender and receiver located? By the way, what is the IGMP version used by the receiver? Can you try to force it to be IGMPv2? Some switches have problems with IGMPv3. Also, do you have any storm control or switchport block configured? Is it perhaps possible to post the configuration of the switch?

Also please be more specific about the IP address of the sender and the individual multicast groups.

Thanks!

Best regards,

Peter

Yes, the receiver and sender are on the same physical switch and on the same vlan.

Show ip igmp snooping group:

C7000-1-SW#sh ip igmp snooping groups

Vlan Group Type Version Port List

-----------------------------------------------------------------------

12 224.1.1.1 igmp v2 Gi2/0/5, Gi2/0/11,

Gi2/0/15, Gi2/0/26

12 224.1.1.2 igmp v2 Gi1/0/10, Gi2/0/11,

Gi2/0/26

12 224.1.1.3 igmp v2 Gi2/0/11, Gi2/0/15,

Gi2/0/26

12 230.230.230.230 igmp v2 Gi2/0/11, Gi2/0/26

C7000-1-SW#

Sender: port g2/0/11

Receiver: port g2/0/15

I dont believe I have any storm control configured unless there is some sort of storm control enabled by default. No switchport blocked. Below is the config of the switch minus interfaces that aren't configured:

version 12.2

no service pad

service timestamps debug datetime msec

service timestamps log datetime msec

service password-encryption

!

hostname C7000-1-SW

!

boot-start-marker

boot-end-marker

!

!witch 1 provision ws-cbs3120g-s

switch 2 provision ws-cbs3120g-s

system mtu routing 1500

vtp mode transparent

ip subnet-zero

ip routing

ip multicast-routing distributed

spanning-tree mode rapid-pvst

spanning-tree extend system-id

!

vlan internal allocation policy ascending

!

vlan 10

name MGMT

!

vlan 12

name SERVERS

!

interface GigabitEthernet1/0/11

switchport access vlan 12

spanning-tree portfast

!

interface GigabitEthernet1/0/12

switchport access vlan 12

spanning-tree portfast

!

interface GigabitEthernet1/0/13

switchport access vlan 12

spanning-tree portfast

!

interface GigabitEthernet1/0/14

switchport access vlan 12

spanning-tree portfast

!

interface GigabitEthernet1/0/15

switchport access vlan 12

spanning-tree portfast

!

interface GigabitEthernet2/0/26

description TRUNK TO 7206 G0/2

switchport mode trunk

spanning-tree portfast

!

interface Vlan10

ip address 10.10.0.2 255.255.255.0

ip pim passive

!

ip route 0.0.0.0 0.0.0.0 10.10.0.1

Thanks for the help!

I noticed that I have the command

"ip multicast-routing distributed" on what I want to use as my switch. (Meaning this device is layer 3 capable but I am using it for layer 2 except for one unrelated connection.)

Could the fact that I have ip multicast-routing distributed configured on this layer 3 switch, be preventing layer 2 multicast functionality?

C7000-1-SW#sh ip igmp snooping querier

Vlan IP Address IGMP Version Port

-------------------------------------------------------------

10 10.10.0.2 v2 Router

12 10.10.2.1 v2 Gi2/0/26

C7000-1-SW#

Vlan 12 is where all multicast is originating from.

Hello Jesse,

an IGMP querier is detected in Vlan12.

However, I would try the following:

create SVI interface Vlan12 with appropriate ip address and enables ip pim sparse mode on it.

your note about ip multicast-routing looks like meaningful.

Hope to help

Giuseppe

Hello Jesse,

As Giuseppe has indicated, removing the "ip multicast-routing" might be worth trying although I would be surprised it if helped.

Giuseppe, can you please confirm my observation that according to the "show ip igmp snooping group", the switch recognizes both the source and the receiver ports and should be forwarding the multicast stream?

Jesse, you have written that the configuration shown above contains the ports that are not left at their default configuration. However, the ports shown in the configuration are Gi1/0/x while the other show commands say about Gi2/0/x - is that just a typo? If not then please let us also see the configuration of the Gi2/0/x interfaces.

Best regards,

Peter

Hi Peter.

To address your question about interfaces indicated in my posts...if I'm understanding you correctly, you're comparing my first post to my second post. If this is correct, my first post reflects my router interfaces while the other configureation represents the switch configuration. I am a bit stumpted (easy to do) as well, because since the sender and receiver are on the same physical switch and vlan, not layer 3 device should be needed to forward the mcast stream.

Any additional thoughts are greatly appreciated.

Jesse

Hi Jesse,

I am referring to this post:

C7000-1-SW#sh ip igmp snooping groups

Vlan Group Type Version Port List

-----------------------------------------------------------------------

12 224.1.1.1 igmp v2 Gi2/0/5, Gi2/0/11,

Gi2/0/15, Gi2/0/26

12 224.1.1.2 igmp v2 Gi1/0/10, Gi2/0/11,

Gi2/0/26

12 224.1.1.3 igmp v2 Gi2/0/11, Gi2/0/15,

Gi2/0/26

12 230.230.230.230 igmp v2 Gi2/0/11, Gi2/0/26

C7000-1-SW#

Sender: port g2/0/11

Receiver: port g2/0/15

A few lines under it, there a configuration snippet of the C7000-1-SW, however, the ports there are Gigabit1/0/x, not Gigabit2/0/x.

Best regards,

Peter

Hello Giuseppe. Thank you for looking at my post. I am not sure how to configure an SVI interface. I will have to read up on it and try it. Am I correct in assuming that the SVI interface should be created on the switch?

Much thanks,

Jesse

Hello Jesse,

yes it should be created on the switch with

conf t

int vlan 12

ip address 10.10.2.x 255.255.255.0

ip pim sparse-mode

no shut

! choice a free ip address in vlan 12 for the SVI

I would also

int vlan10

ip pim sparse-mode

add also the correct

ip pim rp

command

I see on the router a strange mroute regarding ip subnet of vlan12 with a local next-hop that of vlan10.

However, an IGMP querier is detected and sh ip igmp group shows ports for sender, router interface and receiver in vlan12.

Hope to help

Giuseppe

Yes. I see the erroneous staic mroute you mentioned. Hmmm, that shouldn't be there. Thank you for point that out. (I'm not sure if removing that static mroute will fix my issue, but it definitely not be there.)

Thank you

Mohamed Sobair
Level 7
Level 7

Hi Jesse,

Does the Multicast sender and reciever both on vlan 12 or in differnet Vlans? I notice you have ports on vlan 12 while clan 10 is managment right?

If its on the same Vlan, then you should with the current config.

If its on differnt SVI, then enable pim on both layer-3 SVIs with (Ip multicast routing distributed) and you should be good to go.

On the other hand, the command (IP IGMP Snooping) is helpful whenever there is IGMP query from a router or a layer-3 Interface, it allows the switch to build a multicast table tp the appropriate multicast recievers.

HTH

Mohamed

Hi Mohamed. Yes, both sender and receiver in this case are on the same vlan. (vlan 12) You are also correct. I am using Vlan 10 for management. (I dont really need multicast to or from vlan 10)

Thing is, even though this switch is layer 3 capable, I would really like to keep its function as layer 2 device only. So, if possible, I'd like to keep layer 3 functions off. I will build SVI interfaces and enable PIM but do you think I can get around that? (Just use this device as layer 2 only with regards to multicast?)

Thank you all very much for your help so far.

Jesse

Mohamed Sobair
Level 7
Level 7

Hi Jesse,

You dont actually need layer-3 here.

However, if the Multicast sender and reciever on the same vlan , then you dont need extra config and the multicast packet should be forwarded to the all ports of vlan 12 except the port a multicast packet recieved on.

The config suggested by Gui and Peter I believe because of the (sh igmp snooping group) output which shows the reciever and sender detected on different vlans and different ports. If its not in different vlan then you dont need to assign an SVI interface on vlan 12.

HTH

Mohamed

Hello Mohamed,

Can you please re-post the output snippet where you see that the sender and recipient are on different VLANs? I can't find it - I am probably missing something.

Best regards,

Peter

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