Cisco Bug: CSCuk45735 - Enabling CEFv6 breaks IPv6 tunnels
Feb 03, 2017
- Cisco IOS
Known Affected Releases
12.2(17.10)SWB5 12.2(18)S3 12.2(19.7)SPI4i 12.2S 12.2SPI4
Symptoms: For all IPv6 tunnel modes (that is, 6to4, auto, Intra-Site Automatic Tunnel Addressing Protocol [ISATAP], or manual) connectivity to endpoint destinations that are reachable via the tunnel may fail, preventing any traffic from being forwarded. In addition, when packets that exceed the IPv6 maximum transmission unit (MTU) of the tunnel are forwarded to the tunnel headend router, the headend router may fail to send a "packet too big" Internet Control Message Protocol for IPv6 (ICMPv6) message to the source address of the packet. Conditions: These symptoms are observed on a Cisco router only when Cisco Express Forwarding version 6 (CEFv6) is enabled.
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