Hi,
I have a problem with an IPv6 tunnel (ipv6ip) on a Cisco 1841 runnining 15.1(4)M4 or 15.1(4)M5.
It appears that a bug was introduced into 15.1(4)M4 and it is related to IPv6 tunnels and IP SLA.
interface Tunnel64
description IPv6 Tunnel to x.x.x.x
ipv6 address 2001:XXXX:XXXX:XXXX::2/64
tunnel source ATM0/1/0.1
tunnel mode ipv6ip
tunnel destination x.x.x.x
!
After reloading the router, I can see the size of the input queue slowly increasing "Input queue: 30/75/0/0". It appears that specific packets are getting stuck in the input queue while still processing the majority of IPv6 packets. After a short period of time the input queue gets wedged "Input queue: 76/75/0/0" and it stops working for IPv6 unless I reload the router.
Tunnel64 is up, line protocol is up
Hardware is Tunnel
Description: IPv6 Tunnel to x.x.x.x
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 x.x.x.x (ATM0/1/0.1), destination x.x.x.x
Tunnel Subblocks:
src-track:
Tunnel64 source tracking subblock associated with ATM0/1/0.1
Set of tunnels with source ATM0/1/0.1, 1 member (includes iterators), on interface <OK>
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 00:00:15, output 00:00:15, output hang never
Last clearing of "show interface" counters never
Input queue: 76/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/0 (size/max)
30 second input rate 0 bits/sec, 0 packets/sec
30 second output rate 0 bits/sec, 0 packets/sec
2253 packets input, 1691254 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
1844 packets output, 730645 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
I also have an IP SLA probe on the router to verify if connectivity is working over the IPv6 tunnel:
ip sla 10
icmp-echo 2001:XXXX:XXXX:XXXX::1
!
ip sla schedule 10 life forever start-time now
It appears that IP SLA return packets are getting stuck in the input queue as the input queue increments every time I receive a response to my IP SLA probe (every 60 seconds). I have tried to change the values in the probe (packet size, tos, etc) without any luck. I am able to ping the same IPv6 address normally from the command line without seeing this behaviour.
Can I deduce that this is a potential buffer leak - I can't find anything on Bug Toolkit relating to this.
Has anyone come across this issue before and know any workarounds?
Thanks in advance,
Chris
