Advertising Tunnelling Capability in IS-ISHuaweixuxiaohu@huawei.comOrangebruno.decraene@orange.comBloomberg LProbert@raszuk.netHuaweiuma.chunduri@gmail.comTelefonica I+Dluismiguel.contrerasmurillo@telefonica.comVerizonluay.jalil@verizon.com
Routing Area
ISIS Working GroupSampleDraftSome networks use tunnels for a variety of reasons. A large variety
of tunnel types are defined and the ingress needs to select a type of
tunnel which is supported by the egress. This document defines how to
advertise egress tunnel capabilities in IS-IS Router Capability TLV.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 RFC 2119.Some networks use tunnels for a variety of reasons, such as:Partial deployment of MPLS-SPRING as described in , where IP
tunnels are used between MPLS-SPRING-enabled routers so as to
traverse non- MPLS routers.Partial deployment of MPLS-BIER as described in Section 6.9 of
, where IP tunnels are
used between MPLS-BIER-capable routers so as to traverse non
MPLS-BIER
routers.Partial deployment of IPv6 (resp. IPv4) in IPv4 (resp. IPv6)
networks as described in , where IPvx
tunnels are used between IPvx-enabled routers so as to traverse
non-IPvx routers.Remote Loop Free Alternate repair tunnels as described in , where tunnels are used between the Point of
Local Repair and the selected PQ node.The ingress needs to select a type of tunnel which is supported by
the egress. This document describes how to use IS-IS Router Capability
TLV to advertise the egress tunnelling capabilities of nodes.This memo makes use of the terms defined in .Routers advertises their supported encapsulation type(s) by
advertising a new sub-TLV of the IS-IS Router CAPABILITY TLV , referred to as Encapsulation Capability sub-TLV.
This sub-TLV SHOULD NOT appear more than once within a given IS-IS
Router CAPABILITY TLV. The scope of the advertisement depends on the
application but it is recommended that it SHOULD be domain-wide. The
Type code of the Encapsulation Capability sub-TLV is TBD1, the Length
value is variable, and the Value field contains one or more Tunnel
Encapsulation Type sub-TLVs. Each Encapsulation Type sub-TLVs indicates
a particular encapsulation format that the advertising router
supports.The Tunnel Encapsulation Type sub-TLV is structured as follows:Tunnel Type (1 octets): identifies the type of tunneling
technology being signaled. This document defines the following
types: L2TPv3 over IP : Type code=1;GRE : Type code=2;Transmit tunnel endpoint : Type
code=3;IPsec in Tunnel-mode : Type
code=4;IP in IP tunnel with IPsec Transport Mode : Type code=5;MPLS-in-IP tunnel with IPsec Transport Mode : Type code=6;IP in IP :
Type code=7;VXLAN : Type code=8;NVGRE : Type code=9;MPLS : Type code=10;MPLS-in-GRE : Type code=11;VXLAN GPE : Type
code=12;MPLS-in-UDP : Type code=13;MPLS-in-UDP-with-DTLS : Type
code=14;MPLS-in-L2TPv3 : Type code=15;GTP: Type code=16;Unknown types are to be ignored and skipped upon
receipt.Length (1 octets): unsigned integer indicating the total number
of octets of the value field.Value (variable): zero or more Tunnel Encapsulation Attribute
sub- TLVs as defined in Section 5.The Tunnel Encapsulation Attribute sub-TLV is structured as as
follows:Sub-TLV Type (1 octet): each sub-TLV type defines a certain
property about the tunnel TLV that contains this sub-TLV. The
following are the types defined in this document:Encapsulation Parameters: sub-TLV type = 1; (See Section
5.1)Encapsulated Protocol: sub-TLV type = 2; (See Section
5.2)End Point: sub-TLV type = 3; (See Section 5.3)Color: sub-TLV type = 4; (See Section 5.4)Sub-TLV Length (1 octet): unsigned integer indicating the total
number of octets of the sub-TLV value field.Sub-TLV Value (variable): encodings of the value field depend on
the sub-TLV type as enumerated above. The following sub-sections
define the encoding in detail.Any unknown sub-TLVs MUST be ignored and skipped. However, if
the TLV is understood, the entire TLV MUST NOT be ignored just because
it contains an unknown sub-TLV.If a sub-TLV is erroneous, this specific Tunnel Encapsulation MUST be
ignored and skipped. However, others Tunnel Encapsulations MUST be
considered.This sub-TLV has its format defined in [RFC5512] under the name
Encapsulation sub-TLV.This sub-TLV has its format defined in [RFC5512] under the name
Protocol Type.The value field carries the Network Address to be used as tunnel
destination address.If length is 4, the Address Family (AFI) is IPv4.If length is 16, the Address Family (AFI) is IPv6.The valued field is a 4 octets opaque unsigned integer.The color value is user defined and configured locally on the
routers. It may be used by the service providers to define
policies.This document requests IANA to allocate a new code point from
registry IS-IS Router CAPABILITY TLV.This document requests IANA to create a new registry "IGP Tunnel
Encapsulation Types" with the following registration procedure:
Assignments of Encapsulation Types are via Standards
Action .This document requests IANA to create a new registry "IGP Tunnel
Encapsulation Attribute Types" with the following registration
procedure:Assignments of Encapsulation Attribute Types are via Standards
Action .Security considerations applicable to softwires can be found in the
mesh framework . In general, security issues of
the tunnel protocols signaled through this IGP capability extension are
inherited.If a third party is able to modify any of the information that is
used to form encapsulation headers, to choose a tunnel type, or to
choose a particular tunnel for a particular payload type, user data
packets may end up getting misrouted, misdelivered, and/or dropped.Security considerations for the base IS-IS protocol are covered in
.This document is partially inspired by .The authors would like to thank Carlos Pignataro and Karsten Thomann
for their valuable comments on this draft.