Extended TCP Options and IPv6 Extension Headers IPFIX Information Elements

1.1. ipv6ExtensionHeaders Issues

The specification of ipv6ExtensionHeaders IPFIX IE does not:¶

• Cover the full extension headers range (Section 4 of [RFC8200]).¶
• Specify the procedure to follow when all bits are exhausted.¶
• Specify a means to export the number of occurences of a given extension header.¶
• Specify how to automatically update the IANA IPFIX registry ([IANA-IPFIX]) when a new value is assigned in [IANA-EH].¶

The last issue is now solved in [I-D.ietf-opsawg-ipfix-fixes] which defines a new IANA registry entitled "ipv6ExtensionHeaders Bits" under the IANA IPFIX registry group [IANA-IPFIX].¶

Section 3 addresses three first issues.¶

1.2. tcpOptions Issues

The specification of tcpOptions IPFIX IE does not:¶

• Describe how any observed TCP option in a packet can be exported using IPFIX. Only TCP options having a kind =< 63 can be exported in a tcpOptions IPFIX IE.¶
• Support means to report the observed Experimental Identifiers (ExIDs) that are carried in shared TCP options (kind=253 or 254) [RFC6994].¶

Section 4 addresses these issues.¶

3.1. ipv6ExtensionHeadersFull Information Element

Name:

ipv6ExtensionHeadersFull¶

ElementID:

TBD1¶

Description:

IPv6 extension headers observed in packets of this Flow. The information is encoded in a set of bit fields. For each IPv6 extension header, there is a bit in this set. The bit is set to 1 if any observed packet of this Flow contains the corresponding IPv6 extension header. Otherwise, if no observed packet of this Flow contained the respective IPv6 extension header, the value of the corresponding bit is 0. The IPv6 extension header associated with each bit is provided in [NEW_IPFIX_IPv6EH_SUBREGISTRY].¶

The value should be encoded in fewer octets as per the guidelines in Section 6.2 of [RFC7011].¶

Abstract Data Type:

unsigned¶

Data Type Semantics:

flags¶

Additional Information:

See the assigned bits to each IPv6 extension header type in [NEW_IPFIX_IPv6EH_SUBREGISTRY].¶

See Section 4 of [RFC8200] for the general definition of IPv6 extension headers and [IANA-EH] for assigned extension header types.¶

Reference:

This-Document¶

• Note to the RFC Editor: Please replace [NEW_IPFIX_IPv6EH_SUBREGISTRY] with the link to the "ipv6ExtensionHeaders Bits" registry created by [I-D.ietf-opsawg-ipfix-fixes].¶

3.2. ipv6ExtensionHeaderCount Information Element

Name:

ipv6ExtensionHeaderCount¶

ElementID:

TBD2¶

Description:

As per [RFC8200], IPv6 nodes must accept and attempt to process extension headers in occurring any number of times in the same packet. This Information Element echoes the order and number of occurences of the same extension header instance in an IPv6 packet.¶

IPFIX reduced-size encoding as per Section 6.2 of [RFC7011] is used as required.¶

 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 ...
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |  EH Type#1    |   Count       |...|  EH Type#n      |   Count       |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Abstract Data Type:

unsigned64¶

Data Type Semantics:

identifier¶

Additional Information:

See the assigned IPv6 extension header types in [IANA-EH].¶

See [RFC8200] for the general definition of IPv6 extension headers.¶

Reference:

This-Document¶

4.1. tcpOptionsFull Information Element

This section specifies a new Information Element to cover the full TCP options range.¶

Name:

tcpOptionsFull¶

ElementID:

TBD3¶

Description:

TCP options in packets of this Flow. The information is encoded in a set of bit fields. For each TCP option, there is a bit in this set. The bit is set to 1 if any observed packet of this Flow contains the corresponding TCP option. Otherwise, if no observed packet of this Flow contained the respective TCP option, the value of the corresponding bit is 0.¶

Options are mapped to bits according to their option numbers. Option number X is mapped to bit position X. TCP option numbers are maintained by IANA.¶

The value should be encoded in fewer octets as per the guidelines in Section 6.2 of [RFC7011].¶

Abstract Data Type:

unsigned¶

Data Type Semantics:

flags¶

Additional Information:

See the assigned TCP option kinds at [IANA-TCP].¶

See [RFC9293] for the general definition of TCP options.¶

Reference:

This-Document¶

4.2. New Information Elements for Shared TCP Options

ExIDs can be either 2 or 4 bytes in length [RFC6994]. Two new IPFIX IEs are defined to accomodate these two lengths without introducing extra complexity in mixing both types in the same IPFIX IE.¶