MPLS
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...
This document defines how to encapsulate an MPLS label stack and its
payload inside the L2TPv3 ...
... L2TPv3 tunnel payload. After defining the MPLS
over L2TPv3 encapsulation procedure, other MPLS ...
... IPsec
are discussed in context with MPLS over L2TPv3 in an Applicability
section. This document only describes encapsulation ...
... section. This document only describes encapsulation and does not
concern itself with all possible MPLS-based applications that may be
enabled over L2TPv3.
...
... L2TPv3 encapsulation
defined in [RFC3931]. The MPLS Label Stack and payload are carried
in their entirety following IP ...
... MPLS Label Stack |
+-+-+-+-+-+-+-+-+-+-+
| MPLS Payload |
+-+-+-+-+-+-+-+-+-+-+
...
...
The L2TPv3 encapsulation carrying a single MPLS label stack entry is
as follows:
...
... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Entry
Figure 2.2 MPLS over L2TPv3 encapsulation
...
... Label Stack Entry
An MPLS label stack entry as defined in [RFC3032].
...
... The optional L2-Specific Sublayer (defined in [RFC3931]) is generally
not present for MPLS over L2TPv3.
...
... bits, etc. are the same as
the "Common Procedures" for IP encapsulation of MPLS defined in
Section 5 of [RFC4023] and are not reiterated here.
...
... signaling protocol. This document concerns itself only with the
encapsulation of MPLS over L2TPv3; thus, the particular method of
...
... MPLS-IPSEC], and this document all
describe methods for carrying MPLS over an IP network. Cases where
MPLS ...
... MPLS over an IP network. Cases where
MPLS over L2TPv3 is comparable to other alternatives are discussed in
this section.
...
... It is generally simpler to have one's border routers refuse to accept
an MPLS packet than to configure a router to refuse to accept certain
MPLS packets ...
... MPLS packet than to configure a router to refuse to accept certain
MPLS packets carried in IP or GRE to or from certain IP ...
... destinations. Thus, the use of IP or GRE to carry MPLS packets
increases the likelihood that an MPLS label-spoofing ...
... header with a value that is very difficult to spoof.
MPLS over L2TPv3 may be advantageous compared to [RFC4023], if:
...
... L2TPv3 tunnel
established for some other reason, and wish to exchange MPLS
packets over that adjacency.
Implementation considerations ...
...
Implementation considerations dictate the use of MPLS over L2TPv3.
For example, a hardware device ...
... L2TPv3 tunnel payload. MPLS can carry a number of different
protocols as payloads. When an MPLS ...
... MPLS can carry a number of different
protocols as payloads. When an MPLS/L2TPv3 flow carries IP-based ...
... mechanisms to ensure that the offered load is reduced appropriately
during periods of congestion. The MPLS/L2TPv3 flow should not exceed
...
... filtering does not provide effective protection
at all unless the decapsulator of MPLS over L2TPv3 validates the IP
source address ...
... purpose.
The MPLS over L2TPv3 encapsulated packets should be considered as
originating at the tunnel ...
... authentication and
integrity. (Note that the authentication and integrity provided will
apply to the entire MPLS packet, including the MPLS label stack.)
...
... authentication and integrity provided will
apply to the entire MPLS packet, including the MPLS label stack.)
Consequently, the implementation MUST support Encapsulating Security
Payload ...
... Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Encoding", RFC 3032prop, January 2001. ...
... Worster, T., Rekhter, Y., and E. Rosen, "Encapsulating MPLS in IP or Generic Routing Encapsulation (GRE ...