Hello Gents,
We have an issue with a very basic GRE configuration ; GRE Tunnel is up/up on one side but up/down on the other side.
It's possible to ping tunnel destination from each side, but the tunnel doesn't come up.
Here are router configs :
R1 (Cisco 3945E Version 15.2(4)M4)
interface Loopback3
ip address 10.10.112.97 255.255.255.252
!
interface Tunnel50
ip address 192.168.255.234 255.255.255.252
tunnel source Loopback3
tunnel destination 10.10.108.57
R1#ping 10.10.108.57 source loopback 3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.10.108.57, timeout is 2 seconds:
Packet sent with a source address of 10.10.112.97
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 96/110/168 ms
R1#sh int tunnel 50
Tunnel50 is up, line protocol is down
Hardware is Tunnel
Internet address is 192.168.255.234/30
MTU 17916 bytes, BW 100 Kbit/sec, DLY 50000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation TUNNEL, loopback not set
Keepalive not set
Tunnel source 10.10.112.97 (Loopback3), destination 10.10.108.57
Tunnel Subblocks:
src-track:
Tunnel50 source tracking subblock associated with Loopback3
Set of tunnels with source Loopback3, 3 members (includes iterators), on interface <OK>
Tunnel protocol/transport GRE/IP
Key disabled, sequencing disabled
Checksumming of packets disabled
Tunnel TTL 255, Fast tunneling enabled
Path MTU Discovery, ager 10 mins, min MTU 92
Tunnel transport MTU 1476 bytes
Tunnel transmit bandwidth 8000 (kbps)
Tunnel receive bandwidth 8000 (kbps)
Last input 00:01:23, output 00:01:37, output hang never
Last clearing of "show interface" counters 02:00:10
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
360 packets input, 21764 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
298 packets output, 14304 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
R2 (Cisco 3745 Version 12.4(7))
interface Loopback1
ip address 10.10.108.57 255.255.255.255
end
!
interface Tunnel50
ip address 192.168.255.233 255.255.255.252
tunnel source Loopback1
tunnel destination 10.10.112.97
!
R2#ping 10.10.112.97 source loopback 1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.10.112.97, timeout is 2 seconds:
Packet sent with a source address of 10.10.108.57
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 92/96/104 ms
R2#sh int tunnel 50
Tunnel50 is up, line protocol is up
Hardware is Tunnel
Internet address is 192.168.255.233/30
MTU 1514 bytes, BW 9 Kbit, DLY 500000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation TUNNEL, loopback not set
Keepalive not set
Tunnel source 10.10.108.57 (Loopback1), destination 10.10.112.97
Tunnel protocol/transport GRE/IP
Key disabled, sequencing disabled
Checksumming of packets disabled
Tunnel TTL 255
Fast tunneling enabled
Tunnel transmit bandwidth 8000 (kbps)
Tunnel receive bandwidth 8000 (kbps)
Last input 00:16:02, output 00:04:58, output hang never
Last clearing of "show interface" counters 00:32:16
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
298 packets input, 14304 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
301 packets output, 14448 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
------------------------------------------------------------------------------
For information, routing is all static.
I tried to activate keepalive and i can see that they are correctly received on each side but tunnel on R1 was still line protocol down; so i removed it.
Jan 15 17:32:28: Tunnel50: sending keepalive, 10.10.112.97->10.10.108.57 (len=24 ttl=255), counter=1
Jan 15 17:32:28: Tunnel50: keepalive received, 10.10.112.97->10.10.108.57 (len=24 ttl=244), resetting counter
I have also checked on bug tool search but i couldn't find any bug related to our issue.
If you add any advice, it will be very appreciated ; ) !
Best Regards,
Adrien
