IS-IS Traffic Engineering (TE)
Metric LAN ExtensionsHuaweiHuawei Bld., No.156 Beiqing Rd.Beijing100095Chinalichenxi1@huawei.comHuaweiHuawei Bld., No. 156 Beiqing Rd.Beijing100095Chinaxuguoqi@huawei.comHuaweiHuawei Bld., No.156 Beiqing Rd.Beijing100095Chinahuzhibo@huawei.comIn certain networks, network-performance criteria (e.g., latency) are
becoming as critical to data-path selection as other metrics.
This document describes extensions to IS-IS Traffic Engineering (TE)
Metric Extensions (RFC 8570) for LAN subnetworks.
These extensions provide a way to distribute and collect
network-performance information in LAN subnetworks.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 BCP 14
[RFC2119] [RFC8174] when, and only when, they
appear in all capitals, as shown here.In certain networks, network-performance criteria (e.g., latency) are
becoming as critical to data-path selection as other metrics.
This document describes extensions to IS-IS Traffic Engineering (TE)
Metric Extensions (RFC 8570) for LAN subnetworks.
These extensions provide a way to distribute and collect
network-performance information in LAN subnetworks.In LAN subnetworks, the Designated Intermediate System (DIS) is
elected and originates the Pseudonode LSP (PN LSP) including all
neighbors of the DIS. Since, on LANs, each router
only advertises one adjacency to the DIS (and doesn't advertise any
other adjacency), each router should advertise the TE metric for
each of its neighbors. Since the parent TLV is advertising an adjcacency to
the DIS, it is necessary to include the System ID of the physical neighbor
in each TE LAN Sub-TLV.This document registers new IS-IS TE sub-TLVs in the "Sub-TLVs for
TLVs 22, 23, 141, 222, and 223" registry. These new sub-TLVs provides
ways to distribute network-performance information in LAN subnetworks.This document registers new sub-TLVs:This sub-TLV advertises the average link delay between two real
connected IS-IS neighbors in LAN. Each router advertises the average
link delay for each of its neighbors inside a newly defined sub-TLV
that is a part of the TLV advertising the adjacency to the DIS (e.g., TLV-22).
The format of this sub-TLV is shown in the following diagram:Type: TBD (suggested value 41) is to be assigned by IANA.Length: 4 + System-ID length.Neighbor System-ID: IS-IS System-ID of length "ID Length" as
defined in [ISO10589].The other fields are the same as defined in [RFC8570] for
Unidirectional Link Delay Sub-TLV.This sub-TLV is optional. This sub-TLV SHOULD appear only once in each
parent TLV.This sub-TLV advertises the minimum and maximum delay values
between two real connected IS-IS neighbors in LAN. Each router
advertises the minimum and maximum delay for each of its neighbors
inside a newly defined sub-TLV that is a part of the TLV advertising
the adjacency to the DIS (e.g., TLV-22).
The format of this sub-TLV is shown in the following diagram:Type: TBD (suggested value 42) is to be assigned by IANA.Length: 8 + System-ID length.Neighbor System-ID: IS-IS System-ID of length "ID Length" as
defined in [ISO10589].The other fields are the same as defined in [RFC8570] for
Min/Max Unidirectional Link Delay Sub-TLV.This sub-TLV is optional. This sub-TLV SHOULD appear only once in each
parent TLV.This sub-TLV advertises the average link delay variation
between two real connected IS-IS neighbors in LAN. Each router
advertises average link delay variation for each of its neighbors
inside a newly defined sub-TLV that is a part of the TLV advertising
the adjacency to the DIS (e.g., TLV-22).
The format of this sub-TLV is shown in the following diagram:Type: TBD (suggested value 43) is to be assigned by IANA.Length: 4 + System-ID length.Neighbor System-ID: IS-IS System-ID of length "ID Length" as
defined in [ISO10589].The other fields are the same as defined in [RFC8570] for
Unidirectional Delay Variation Sub-TLV.This sub-TLV is optional. This sub-TLV SHOULD appear only once in each
parent TLV.This sub-TLV advertises the loss (as a packet percentage)
between two real connected IS-IS neighbors in LAN. Each router
advertises the link loss for each of its neighbors
inside a newly defined sub-TLV that is a part of the TLV advertising
the adjacency to the DIS (e.g., TLV-22).
The format of this sub-TLV is shown in the following diagram:Type: TBD (suggested value 44) is to be assigned by IANA.Length: 4 + System-ID length.Neighbor System-ID: IS-IS System-ID of length "ID Length" as
defined in [ISO10589].The other fields are the same as defined in [RFC8570] for
Unidirectional Link Loss Sub-TLV.This sub-TLV is optional. This sub-TLV SHOULD appear only once in each
parent TLV.This sub-TLV advertises the residual bandwidth
between two real connected IS-IS neighbors in LAN. Each router
advertises the residual bandwidth for each of its neighbors
inside a newly defined sub-TLV that is a part of the TLV advertising
the adjacency to the DIS (e.g., TLV-22).
The format of this sub-TLV is shown in the following diagram:Type: TBD (suggested value 45) is to be assigned by IANA.Length: 4 + System-ID length.Neighbor System-ID: IS-IS System-ID of length "ID Length" as
defined in [ISO10589].The other fields are the same as defined in [RFC8570] for
Unidirectional Residual Bandwidth Sub-TLV.This sub-TLV is optional. This sub-TLV SHOULD appear only once in each
parent TLV.This sub-TLV advertises the available bandwidth
between two real connected IS-IS neighbors in LAN. Each router
advertises the available bandwidth for each of its neighbors
inside a newly defined sub-TLV that is a part of the TLV advertising
the adjacency to the DIS (e.g., TLV-22).
The format of this sub-TLV is shown in the following diagram:Type: TBD (suggested value 46) is to be assigned by IANA.Length: 4 + System-ID length.Neighbor System-ID: IS-IS System-ID of length "ID Length" as
defined in [ISO10589].The other fields are the same as defined in [RFC8570] for
Unidirectional Available Bandwidth Sub-TLV.This sub-TLV is optional. This sub-TLV SHOULD appear only once in each
parent TLV.This sub-TLV advertises the bandwidth utilization
between two real connected IS-IS neighbors in LAN. Each router
advertises the bandwidth utilization (for each of its neighbors)
inside a newly defined sub-TLV that is a part of the TLV advertising
the adjacency to the DIS (e.g., TLV-22).
The format of this sub-TLV is shown in the following diagram:Type: TBD (suggested value 47) is to be assigned by IANA.Length: 4 + System-ID length.Neighbor System-ID: IS-IS System-ID of length "ID Length" as
defined in [ISO10589].The other fields are the same as defined in [RFC8570] for
Unidirectional Utilized Bandwidth Sub-TLV.This sub-TLV is optional. This sub-TLV SHOULD appear only once in each
parent TLV.This document uses the same principle for announcement thresholds and filters
as described in RFC 8570.This document uses the same principle for announcement suppression as described
in RFC 8570.This document uses the same principle for network stability and announcement periodicity
as described in RFC 8570.Implementations MUST make it possible to enable or disable each sub-TLV
based on configuration.Unrecognized sub-TLVs should be silently ignored.TBD.This document requests that IANA allocates new sub-TLV types
from the "Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223 (Extended
IS reachability, IS Neighbor Attribute, L2 Bundle Member Attributes,
inter-AS reachability information, MT-ISN, and MT IS Neighbor
Attribute TLVs)" registry as specified.These extensions to IS-IS do not add any new security issues
to the existing IGP.