BFD StabilityCiena Corporation3939 North 1st StreetSan JoseCA95134USAmishra.ashesh@gmail.comwww.ciena.comCiena Corporation3939 North 1st StreetSan JoseCA95134USAmjethanandani@gmail.comwww.ciena.comCiena Corporation3939 North 1st StreetSan JoseCA95134USAankurpsaxena@gmail.comJuniper NetworksJuniper Networks, Exora Business ParkBangaloreKarnataka560103India+santoshpk@juniper.netHuaweimach.chen@huawei.com
Network
Routing Working GroupInternet-DraftThis document describes extensions to the Bidirectional Forwarding
Detection (BFD) protocol to measure BFD stability. Specifically, it
describes a mechanism for detection of BFD frame loss.The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in <xref
target="RFC2119">RFC 2119</xref>.The Bidirectional Forwarding Detection (BFD) protocol operates by
transmitting and receiving control frames, generally at high frequency,
over the datapath being monitored. In order to prevent significant data
loss due to a datapath failure, the tolerance for lost or delayed frames
(the Detection Time as described in RFC 5880) is set to the smallest
feasible value. This document proposes a mechanism to detect lost frames in a BFD
session in addition to the datapath fault detection mechanisms of BFD.
Such a mechanism presents significant value with the ability to measure
the stability of BFD sessions and provides data to the operators.The functionality proposed for BFD stability measurement is achieved
by appending the Null-Authentication TLV to the BFD control frame.The Null-Authentication TLV (called 0-Auth in this document) extends
the existing BFD Authentication TLV structure by adding a new Auth-Type
of <IANA Assigned>. This TLV carries the Sequence Number for frame
loss measurement.where:Auth Type: The Authentication Type, which in this case is <IANA
assigned> (Null Authentication).Auth Len: The length of the Authentication Section, in bytes. Set to
12. Auth Key ID: The Authentication Key ID in use for this packet. This
MUST be set to zero on transmit, and ignored on receipt.Reserved: This byte MUST be set to zero on transmit, and ignored on
receipt.Reserved for Future: For future extensions. MUST be set to 0 if not
used. Sequence Number: This indicates the sequence number for this packet
and MUST be present in every 0-Auth TLV. This value is incremented by 1
for every frame transmitted while the session state is UP. A value of 0
indicates a request by sender to reset the sequence number correlation
logic at the receiver. The first frame transmitted by the sender MAY set
this field to 0.This mechanism allows operator to measure the loss of BFD CC frames.
This measurement counts the number of BFD control frames missed at
the receiver due to a transient change in the network such as
congestion. Frame-loss is detected by comparing the Sequence Number
field in the 0-Auth TLV in successive BFD CC frames. The Sequence Number
in each successive control frame generated on a BFD session by the
transmitter is incremented by one.The first BFD Loss-Delay TLV processed by the receiver that has a
non-zero sequence number is used for bootstrapping the logic. Each
successive frame after this is expected to have a Sequence Number that
is one greater than the Sequence Number in the previous frame.IANA is requested to assign new Auth-Type for the Null-Authentication
TLV for BFD Stability Measurement. The following number is
suggested.Value Meaning6 Null-Authentication TLVSince this method uses an authentication TLV to achive the
functionality, usage of this TLV will prevent the use of other
authentication TLVs.Nobo Akiya, Jeffery Haas, Peng Fan, Dileep Singh, Basil Saji, Sagar
Soni and Mallik Mudigonda also conributed to this document.