IPv6 – Setting up a connection to a Tunnel Broker (Part 7)

If you have been following this series, we have a functional Tunnel Broker connection at this point. Now is a good time to learn a few troubleshooting commands to help build a baseline of when things are working right or arent working.

show ipv6 route – This shows up what IPv6 routes are currently present on the Tunnel Broker router. Since we are using a static default route, what you should see would be something like this –

IPv6 Routing Table – Default – 6 entries
Codes: C – Connected, L – Local, S – Static, U – Per-user Static route
B – BGP, M – MIPv6, R – RIP, D – EIGRP
EX – EIGRP external
O – OSPF Intra, OI – OSPF Inter, OE1 – OSPF ext 1, OE2 – OSPF ext 2
ON1 – OSPF NSSA ext 1, ON2 – OSPF NSSA ext 2
S ::/0 [1/0]
via Tunnel0, directly connected
C 2001:470:1F10:102::/64 [0/0]
via Tunnel0, directly connected
L 2001:470:1F10:102::2/128 [0/0]
via Tunnel0, receive
C 2001:470:1F11:102::/64 [0/0]
via Vlan1, directly connected
L 2001:470:1F11:102::1/128 [0/0]
via Vlan1, receive
L FF00::/8 [0/0]
via Null0, receive

show ipv6 interface brief – This shows is that the Tunnel interface is up –

Vlan1 [up/up]
Tunnel0 [up/up]

show interfaces tunnel 0
– This confirms how the tunnel is configured, that there is traffic passing and some other good pieces of info to have if you are troubleshooting problems.

Tunnel0 is up, line protocol is up
Hardware is Tunnel
Description: Hurricane Electric IPv6 Tunnel Broker
MTU 17920 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 (FastEthernet1), destination
Tunnel protocol/transport IPv6/IP
Tunnel TTL 255
Tunnel transport MTU 1480 bytes
Tunnel transmit bandwidth 8000 (kbps)
Tunnel receive bandwidth 8000 (kbps)
Last input 3d17h, output 01:00:54, output hang never
Last clearing of “show interface” counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 3
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
11390 packets input, 11803712 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
10004 packets output, 1513696 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out

sh ipv6 routing protocols – This shows us what type of routing protocols are running on our router –

IPv6 Routing Protocol is “connected”
IPv6 Routing Protocol is “static”

debug ipv6 packet detail – This shows you the traffic going over the IPv6 tunnel connection

003814: Feb 10 18:56:47: IPv6-Fwd: Sending on Vlan1
003815: Feb 10 18:56:47: IPv6: Looking up 2001:470:1F11:102:5AB0:35FF:FE88:D4C6 [Source 2001:470:1F11:102::1] in FIB
003816: Feb 10 18:56:47: IPv6: FIB lookup for 2001:470:1F11:102:5AB0:35FF:FE88:D4C6 succeeded. if=Vlan1, nexthop 2001:470:1F11:102:5AB0:35FF:FE88:D4C6
003817: Feb 10 18:56:47: IPV6: source 2001:470:1F11:102::1 (local)
003818: Feb 10 18:56:47: dest 2001:470:1F11:102:5AB0:35FF:FE88:D4C6 (Vlan1)
003819: Feb 10 18:56:47: traffic class 192, flow 0x0, len 620+0, prot 6, hops 255, originating

There are other commands that you can use if you had a routing protocol running such as if you had additional IPv6 subnets assigned from your Tunnel Broker endpoint such as sh ip ospf neighbor and sh ipv6 rip to mention just a couple of the options.

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