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Multicast over GRE issue

darron
Level 1
Level 1

Good day!

I've been messing with this configuration for about a week now and cannot figure out where the issue lies.

Site A configured for a GRE tunnel to Site B at a remote location and working great. The issue is that I don't seem to be passing multicast traffic across the tunnel to the remote location.

97.97.97.97 = Gigabit Interface (Site A Public IP- Static)

98.98.98.98 = Gigabit Interface (Site B Public IP- Dynamic)

10.1.1.1 = RP (Site A Loopback0)

10.5.5.1 = Multicast Source

10.5.5.239 = DHCP for Client devices

Site A

interface Tunnel0
description mGRE Tunnel
ip address 172.16.100.1 255.255.255.0
no ip redirects
ip pim sparse-mode
ip nhrp map multicast dynamic
ip nhrp network-id 1234
tunnel source 97.97.97.97
tunnel mode gre multipoint

ip route 10.100.0.0 255.255.255.0 172.16.100.2

Site B

interface Tunnel0
description mGRE Tunnel
ip address 172.16.100.2 255.255.255.0
no ip redirects
ip pim sparse-mode
ip nhrp map multicast dynamic
ip nhrp map 172.16.100.1 97.97.97.97
ip nhrp map multicast 10.1.1.1
ip nhrp network-id 1234
ip nhrp nhs 172.16.100.1
tunnel source GigabitEthernet0/0
tunnel mode gre multipoint

interface Vlan100
ip address 10.100.0.1 255.255.255.0
ip helper-address 10.5.5.239
ip pim sparse-mode

ip route 10.5.5.0 255.255.255.0 172.16.100.1

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

SiteB#sh ip pim rp
Group: 239.255.255.250, RP: 10.1.1.1, uptime 00:15:29, expires never
Group: 239.255.53.10, RP: 10.1.1.1, uptime 00:15:19, expires never
Group: 224.0.1.40, RP: 10.1.1.1, uptime 1d00h, expires never

SiteB#sh ip pim ne
PIM Neighbor Table
Mode: B - Bidir Capable, DR - Designated Router, N - Default DR Priority,
P - Proxy Capable, S - State Refresh Capable, G - GenID Capable
Neighbor Interface Uptime/Expires Ver DR
Address Prio/Mode
172.16.100.1 Tunnel0 1d00h/00:01:16 v2 1 / S P G

SiteB#sh ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group,
G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
Q - Received BGP S-A Route, q - Sent BGP S-A Route,
V - RD & Vector, v - Vector, p - PIM Joins on route,
x - VxLAN group
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.255.255.250), 00:17:06/00:02:46, RP 10.1.1.1, flags: SJC
Incoming interface: GigabitEthernet0/0, RPF nbr 10.1.1.1
Outgoing interface list:
Vlan100, Forward/Sparse, 00:17:06/00:02:46

(*, 239.255.53.10), 00:16:56/00:02:51, RP 10.1.1.1, flags: SJC
Incoming interface: GigabitEthernet0/0, RPF nbr 10.1.1.1
Outgoing interface list:
Vlan100, Forward/Sparse, 00:16:56/00:02:51

(*, 224.0.1.40), 1d00h/00:02:44, RP 10.1.1.1, flags: SJCL
Incoming interface: GigabitEthernet0/0, RPF nbr 10.1.1.1
Outgoing interface list:
Tunnel0, Forward/Sparse, 00:20:26/00:02:44

SiteB#ping 10.5.5.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.5.5.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 60/63/68 ms

SiteB#traceroute 10.5.5.1
Type escape sequence to abort.
Tracing the route to 10.5.5.1 
VRF info: (vrf in name/id, vrf out name/id)
1 172.16.100.1 64 msec 68 msec 68 msec
2 10.254.106.2 72 msec 72 msec 64 msec
3 10.5.5.1 60 msec 60 msec 68 msec

I'm looking for any assistance on this...

4 Replies 4

darron
Level 1
Level 1

Is there more information needed for troublshooting?

Hello.

From site B your RP is reachable via G0/0, but should be over PIM-enabled interface (tunnel).

PS: if it's mGRE - you will need nbma pim behaviour + NHS mush be DR, but if you keep only two devices - migrate to a simple GRE tunnel.

I suspect RFC failure cause the problem, can you please show ip mroute count on both sides?

What is the use of "count" if RPF interface is incorrect?

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