I am trying to configure a GRE tunnel between a CE6850 & a Cisco Catalyst 6509 switch.
However the tunnel will not come up on the 6850, although i have layer 3 connectivity between the source & destination ip address's. Can anyone help?

CE6850 configuration...
interface Tunnel0
 ip address 192.168.121.1 255.255.255.252
 tunnel-protocol gre
 source 10.163.50.14
 destination 10.34.75.2

Cisco 6509 configuration...
interface Tunnel0
 ip address 192.168.121.2 255.255.255.252
 tunnel source 10.34.75.2
 tunnel destination 10.163.50.14

<Huawei-6850>dis int t0
Tunnel0 current state : DOWN (ifindex: 156)
Line protocol current state : DOWN
Route Port,The Maximum Transmit Unit is 1500, Current BW: 65.53Kbps
Internet Address is 192.168.121.1/30
Encapsulation is TUNNEL, loopback not set
Tunnel source 10.163.50.14 (Vlanif1073), destination 10.34.75.2
Tunnel protocol/transport GRE/IP, key disabled
keepalive enable period 10 retry-times 3
Checksumming of packets disabled
Current system time: 2017-08-04 15:05+01:00 DST
    300 seconds input rate 0 bits/sec, 0 packets/sec
    300 seconds output rate 0 bits/sec, 0 packets/sec
    0 seconds input rate 0 bits/sec, 0 packets/sec
    0 seconds output rate 0 bits/sec, 0 packets/sec
    0 packets input,  0 bytes
    0 input error
    0 packets output,  0 bytes
    0 output error
    Input:
      Unicast: 0 packets, Multicast: 0 packets
    Output:
      Unicast: 0 packets, Multicast: 0 packets
    Input bandwidth utilization  : --
    Output bandwidth utilization : --

Cisco-6509#show int t0
Tunnel0 is up, line protocol is up
  Hardware is Tunnel
  Internet address is 192.168.121.2/30
  MTU 17868 bytes, BW 100 Kbit, DLY 50000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation TUNNEL, loopback not set
  Keepalive not set
  Tunnel source 10.34.75.2, destination 10.163.50.14
  Tunnel protocol/transport GRE/IP
    Key disabled, sequencing disabled
    Checksumming of packets disabled
  Tunnel TTL 255, Fast tunneling enabled
  Tunnel transport MTU 1476 bytes
  Last input 03:42:34, output 00:21:58, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/0 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
  L2 Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes
  L3 in Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes mcast
  L3 out Switched: ucast: 0 pkt, 0 bytes mcast: 0 pkt, 0 bytes
     54 packets input, 4660 bytes, 0 no buffer
     Received 0 broadcasts (0 IP multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     4594 packets output, 221652 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 output buffer failures, 0 output buffers swapped out