multicast routing between two sites over GRE tunnel

corycandia · ‎03-23-2017

Experts,

I cannot figure out how to properly configure multicast routing over a GRE tunnel connecting two sites.

Can anyone provide instruction on how to configure routers along a path for DLNA multicast traffic?

The multicast traffic is DLNA traffic UDP port 1900 to address 239.255.255.250. (It's basically an announcement of its existence)

The two sites are connected via a DMVPN GRE between two routers (a 2821 and a 2811).

The topology is this:

Site A (192.168.0.0/24) DLNA device

3750 doing inter-vlan routing

connected via /30

2821

connected via DMVPN GRE over to site B

2811 doing router on a stick

Site B (10.1.1.0/24) DLNA device

I have configured ip multicast-routing on all three routers

I have enabled ip PIM dense-mode on all interfaces (starting with dense mode, then attempting to configure sparse)

I have tried using various combinations of ip igmp static-group 239.255.255.250 entries on the interfaces, and the broadcasts still don't make it across.

The devices sending out the DLNA multicast packets likely don't do IGMP the way a normal receiver would, they just blast out the device announcement that says 'I'm here and a DLNA device', so I imagine that's part of why the broadcasts aren't making it to the other side if the routers aren't being told to join, but I thought the static-group command would over come that.

Can anyone provide some ideas?

Thanks.

Jon Marshall · ‎03-23-2017

Not familiar with DNLA but not clear what you mean when you say the devices sending the stream don't do IGMP like a receiver because it's not the sending devices that send IGMP joins. Not trying to be clever (I can't anyway:)) just trying to understand it.

Anyway what do the mroute tables on all the devices show ?

Jon

corycandia · ‎03-24-2017

Here's the output from show ip mroute on the 3750 at site A (it's the first router and default gateway for all the Site A hosts):

(*, 239.255.255.250), 5d15h/stopped, RP 0.0.0.0, flags: DC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Vlan5, Forward/Dense, 5d15h/00:00:00
GigabitEthernet1/0/2, Forward/Dense, 5d15h/00:00:00

(192.168.0.203, 239.255.255.250), 00:00:38/00:02:26, flags: T
Incoming interface: Vlan5, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0/2, Forward/Dense, 00:00:38/00:00:00

(192.168.0.202, 239.255.255.250), 00:03:01/00:00:06, flags: T
Incoming interface: Vlan5, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0/2, Forward/Dense, 00:03:01/00:00:00

(192.168.0.103, 239.255.255.250), 00:56:37/00:02:59, flags: T
Incoming interface: Vlan5, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0/2, Forward/Dense, 00:56:39/00:00:00

(192.168.0.127, 239.255.255.250), 2d03h/00:02:35, flags: T
Incoming interface: Vlan5, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0/2, Forward/Dense, 2d03h/00:00:00

(192.168.0.26, 239.255.255.250), 5d15h/00:02:55, flags: T
Incoming interface: Vlan5, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0/2, Forward/Dense, 5d15h/00:00:00

(*, 224.0.1.40), 5d15h/00:02:51, RP 0.0.0.0, flags: DCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0/2, Forward/Dense, 5d15h/00:00:00
Vlan5, Forward/Dense, 5d15h/00:00:00

192.168.0.26 is the DLNA server. .202 and .203 are renders (media players). All of them send out the multicast broadcast announcing their presence.

Here's the output of the 2821 at Site A:

(*, 239.255.255.250), 00:24:06/00:02:04, RP 0.0.0.0, flags: D
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0, Forward/Dense, 00:24:06/stopped
Tunnel1, Forward/Dense, 00:24:06/stopped

(*, 224.0.1.40), 7w0d/00:02:55, RP 0.0.0.0, flags: DCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Tunnel1, Forward/Dense, 5d15h/stopped
GigabitEthernet1/0, Forward/Dense, 5d15h/stopped
Vlan21, Forward/Sparse-Dense, 10w5d/stopped

and the output of Site B router:

(*, 239.255.255.254), 5d15h/00:01:59, RP 0.0.0.0, flags: DC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0.1, Forward/Dense, 5d15h/stopped
Tunnel1, Forward/Dense, 5d15h/stopped

(*, 239.0.0.250), 5d15h/00:02:56, RP 0.0.0.0, flags: DC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0.1, Forward/Dense, 5d15h/stopped
Tunnel1, Forward/Dense, 5d15h/stopped

(*, 239.255.255.250), 5d15h/00:02:54, RP 0.0.0.0, flags: DC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0.1, Forward/Dense, 5d15h/stopped
Tunnel1, Forward/Dense, 5d15h/stopped

(*, 224.0.1.40), 5d15h/00:02:56, RP 0.0.0.0, flags: DCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Tunnel1, Forward/Dense, 5d15h/stopped

As you can see, I can't get the broadcasts to make it to the other side.

Jon Marshall · ‎03-24-2017

What does gi1/0/2 on the 3750 connect to, is it the 2821 ?

Where did you add the static join command ie. what interfaces on which devices ?

Jon

corycandia · ‎03-24-2017

"What does gi1/0/2 on the 3750 connect to, is it the 2821?"

Gi1/0/2 on the 3750 connects to Gi1/0 on the 2821, yes sir. (NME-X-23ES-1G-P)

"Where did you add the static join command ie. what interfaces on which devices ?"

I've tried adding it on the inside interface on site B (gi1/0.1, the default gateway for Site B hosts) and I've tried adding it to every interface in the chain/path.

Jon Marshall · ‎03-24-2017

Can you add this to the tunnel interface on the 2811 at site B -

"ip igmp static-group 239.255.255.250 source 192.168.0.26"

and then post the mroute tables again from just the two routers.

Jon

corycandia · ‎03-24-2017

2821 (Site A)

(*, 239.255.255.250), 00:55:44/00:02:35, RP 0.0.0.0, flags: D
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0, Forward/Dense, 00:55:44/stopped
Tunnel1, Forward/Dense, 00:55:44/stopped

(*, 224.0.1.40), 7w0d/00:02:18, RP 0.0.0.0, flags: DCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Tunnel1, Forward/Dense, 5d16h/stopped
GigabitEthernet1/0, Forward/Dense, 5d16h/stopped
Vlan21, Forward/Sparse-Dense, 10w5d/stopped

2811 (Site B)

(*, 239.255.255.254), 5d16h/00:02:17, RP 0.0.0.0, flags: DC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0.1, Forward/Dense, 5d16h/stopped
Tunnel1, Forward/Dense, 5d16h/stopped

(*, 239.0.0.250), 5d16h/00:02:23, RP 0.0.0.0, flags: DC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0.1, Forward/Dense, 5d16h/stopped
Tunnel1, Forward/Dense, 5d16h/stopped

(*, 239.255.255.250), 5d16h/00:02:46, RP 0.0.0.0, flags: DC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet1/0.1, Forward/Dense, 5d16h/stopped
Tunnel1, Forward/Dense, 5d16h/stopped

(*, 224.0.1.40), 5d16h/00:02:11, RP 0.0.0.0, flags: DCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Tunnel1, Forward/Dense, 5d16h/stopped

I found something in all my research I wonder if you can weigh in on regarding this exact action:

http://www.cisco.com/c/en/us/support/docs/ip/ip-multicast/119383-technote-ip-multicast-00.html#anc5

They seem to specify that the routers care about a designated router for PIM?

I wonder if this matters?

The designated router for PIM between the 2821 in Site A and the 2811 in Site B is the 2821. This is the segment that crosses the GRE tunnel.

I confirmed this by running show ip pim interface

Jon Marshall · ‎03-24-2017

The PIM DR is responsible for sending the join message to the RP but you are not using an RP because you are in dense mode at the moment. Whether or not this still applies I am not sure.

From the outputs of the mroute tables it would appear the 3750 is forwarding the stream to the 2821 but that is as far as it gets at the moment.

So you have definitely configured PIM on all the L3 interfaces in the path ?

If so then not sure at the moment. When I get the time I will do a quick lab to test multicast across GRE although I don't think that is the issue and do some testing with the DR.

Jon

corycandia · ‎03-24-2017

3750#debug ip mpacket shows:
5w1d: IP(0): s=192.168.0.202 (Vlan5) d=239.255.255.250 (GigabitEthernet1/0/2) id=0, t tl=3, prot=17, len=300(300), mforward

but I did not see the packet on the 2811 for some reason with same debug enabled.

Not sure how to further debug, but I'll try debugging IGMP and see if I can interpret the output.

THanks your your help and interest Jon.

corycandia · ‎03-24-2017

I might have found the issue which makes me feel a little stupid.

TTL might be set to 1 coming into the first router and then not getting forwarded to the next.

I am capturing packets on the 3750's Gi1/0/2 (routed link between the 3750 and the 2821. The 239.255.255.250 packets get getting forwarded to the 2821, but with a TTL of 1. It can't make it though through the 2821 and 2811 to the other side.

Maybe I need to search being able to modify the TTL with a policy map if that's possible?

Jon Marshall · ‎03-24-2017

That would certainly stop it working and account for the 2821's mroute table but from your debug on the 3750 I thought it said the TTL was 3 or perhaps I am misreading the output.

As for increasing it this is usually done on the device transmitting the stream ie. I have never done it with the actual network devices.

Jon

corycandia · ‎03-24-2017

Here is relevant config info if it helps.