RFC4884 ICMPv6 and MPLSv6
RFC 4884 redefines selected ICMP error messages to support multi-part operation.
A multi-part ICMP message carries all of the information that ICMP messages carried previously, as well as additional information that applications may require.
RFC 4884 feature introduces an 8-bit length attribute to the following ICMPv6 messages with extensions.
- Destination Unreachable (type = 1)
- Time Exceeded (type = 3)
As part of RFC 4884 feature, for applications like MPLS/trace route which add extensions to type 1 and type 3 ICMPv6 error messages, original datagram length will be added in ICMPv6 header.
Also, infra is added as part of RFC 4884 support. If any new application is adding extensions it has to call defined registries to be compliant with RFC 4884.
Backward compatibility is also taken care of as part of this feature.
This feature is enabled by default and a CLI [no] ipv6 icmp od-length enable is provided which is enabled by default.
ipv6 icmp od-length enable
RFC4884 ICMP v4 and MPLS v4 extensions will be supported in the IOS-XE 17.6.1 release.