Multicast traffic over mGRE or DMVPN

[mohammedsalih]

Hi every one,

i have more than 250 site they are connected to  an ASR 1000 Series cisco router

i tried to create dmvpn tunnel the ASR is the hub and the rest of 250 site are the spokes . (without encryption)

the DMVPN is work fine and eigrp up on all sites .but the multicast traffic not working. i have applications on each site work with multicast traffic only.

can anyone explain is that possible or i must create gre tunnel point to point?

[Larry Sullivan]

Did you put PIM and IGMP on Hub and Spoke tunnels?

Likely need the below on tunnels depending on your set up.  Maybe test with Hub and a single spoke.

ip pim nbma-mode

ip pim sparse-dense-mode

ip igmp version 3

[mohammedsalih]

i already do that and its not working, the issue is the Hub not forward the multicast traffic from spoke to spoke or fro spoke to hub

Hub configuration:

ip  add 172.19.2.254 255.255.255.0

no ip redirect

no ip unreachable

no ip proxy-arp

no split-horizon eigrp 77

ip pim nbma-mode

ip pim sparse-dense-mode

ip nhrp network-id 222

ip igmp version 3

tunnel source gi1/0/0.98

tunnel mode multipoint

tunnel key 222

The Spoke configuration:

int tunnel192

ip add 172.19.2.14 255.255.255.0

ip nbar protocol-discovery

ip pim nbma-mode

ip pim sparse-dense-mode

ip nhrp network-id 222

ip igmp version 3

tunnel source gi1/0/0.98

tunnel mode multipoint

tunnel key 222

tunnel source vlan 120

ip nhrp map multicast 10.120.98.17

ip nhrp map 172.19.2.254 10.120.98.17

ip nhrp nhs 172.19.2.254

[Larry Sullivan]

Only difference I see between your config and our working config is our tunnel mode is "tunnel mode gre multipoint".  Multicast isn't allowed over the internet (as well provider layer 3 private leased lines) as is and needs to be encapsulated in a GRE to work in those situations.

[mohammedsalih]

sorry i do a mistake i wrote the tunnel mode incorrectly

the tunnel mode is "tunnel mode gre multipoint"

and issue still the same.

the ASR (HUB) does not allowed the traffic to go accross it .

[David Ruess]

Can you add the command: ip nhrp map multicast dynamic on the HUB?

-David

[Larry Sullivan]

I'll post our working hub config as I do actually see MTU not configured on yours.  Other than that don't think I help beyond this because I can't jump in and start looking into doing multicast troubleshooting to verify that it set up and operating correctly.

interface Tunnel881
description MP_GRE
bandwidth 1000000
ip address 10.90.71.1 255.255.255.0
no ip redirects
no ip unreachables
no ip proxy-arp
ip mtu 1400
ip pim nbma-mode
ip pim sparse-dense-mode
ip nhrp authentication xxx
ip nhrp network-id xxx
ip nhrp holdtime 120
ip nhrp redirect
ip tcp adjust-mss 1360
ip igmp version 3
tunnel source 10.80.71.1
tunnel mode gre multipoint

[mohammedsalih]

the test work form the hub towards the spoke  or the opposite only.

i want spoke to spoke .

i have large number of sites and it not makes sense to configure manually all the sites by doing gre point to point or manually ip nhrp map multicast for each site .

if the dmvpn not work, do you have any idea to do scalable way to make it work?

[MHM Cisco World]

Sorry dmvpn there is no spoke to spoke multicast 

The multicast must be spoke hub spoke.

I read it in cisco doc. Before but contact cisco for more sure about this point.

[mohammedsalih]

thanks for replying ,

do you have any idea for scalable way to make work?

i have more than 250 router and if apply GRE p2p it going to be mess.

[MHM Cisco World]

It not p2p it p2mp.

But yes hub all do all work for multicast to flow between spokes.

I will check and update you If I get something.

MHM

[mohammedsalih]

i already test form spokes toward the the hub and it works fine .

but spoke to spoke through the hub no multicast traffic generated.

also i applied gre p2p and it work fine  , by adding another tunnel p2p form spokes to hub and enable IGP. but it going to be alot of configuration . i need scalable method to reduce configuration and make tshoot easy.

[Larry Sullivan]

OK, so 1) ip nhrp map multicast has to do with dynamic routing protocols and not actual multicast traffic through the tunnel, so isn't needed for multicast to work but is for routing protocols that use multicast.  2) We use BGP, but as long as the hub has "ip nhrp redirect" and spokes have "ip nhrp shortcut" on their tunnels, all you do in BGP at least is do the BGP peering between spokes and then they will dynamically build DMVPN/NHRP peerings and multicast should work between spokes.

[mohammedsalih]

I tried it , bgp peers work fine but the multicast not working even if i peer between spokes. another issue is peering between spokes still down and come up until there is connnection between these spokes because of the nhrp(Phase 3 of DMVPN).

even if this way works, the problem is still present because it is hard to establish bgp neighbors between alot of spokes.

i have an idea is to establish bgp between the hub towards each spokes (without using dmvpn) i think this method will solve the problem.

thank you for your time i really appreciate that.

with regards

[mohammedsalih · Accepted solution]

i finally solved the issue by enable iBGP peers between the hub towards the spokes and make the hub RRS.

the multicast traffic generated between spokes.

thanks alot for helping.