The IESG has approved the following document:
- 'Maximum Transmission Unit Signalling Extensions for the Label
Distribution Protocol '
<draft-ietf-mpls-ldp-mtu-extensions-03.txt> as an Experimental RFC
This document is the product of the Multiprotocol Label Switching Working
Group.
The IESG contact persons are Alex Zinin and Bill Fenner.
Technical Summary
Proper functioning of RFC 1191 path Maximum Transmission Unit (MTU)
discovery requires that IP routers have knowledge of the MTU for each
link to which they are connected. As currently specified, the Label
Distribution Protocol (LDP) does not have the ability to signal the
MTU for a Label Switched Path (LSP) to the ingress Label Switching
Router (LSR). In the absence of this functionality, the MTU for each
LSP must be statically configured by network operators or by
equivalent, off-line mechanisms.
Working Group Summary
The WG originally submitted the doc for PS. However, since no
implementations have been identified, the target status has been
changed to Experimental.
Protocol Quality
The document has been reviewed for the IESG by Alex Zinin.
RFC Editor Note
1. Disregard the following lines in the document header:
"Updates: 3036"
"Category: Standards Track"
The document target status in Experimental.
2. Second para in Abstract:
OLD:
This document specifies extensions to LDP in support of LSP MTU
discovery.
NEW:
This document specifies experimental extensions to LDP in support
of LSP MTU discovery.
3. Section 5.1 "Interaction With LSRs Which Do Not Support MTU Signalling"
OLD:
Changes in MTU for sections of an LSP may cause intermediate LSRs to
generate unsolicited label Mapping messages to advertise the new MTU.
LSRs which do not support MTU signalling MUST accept these messages,
but MAY ignore them (see Section 2.1).
NEW:
Changes in MTU for sections of an LSP may cause intermediate LSRs to
generate unsolicited label Mapping messages to advertise the new MTU.
LSRs which do not support MTU signalling will, due to message and TLV
processing mechanisms specified in RFC3036 [2] accept the messages
carrying the MTU TLV, but will ignore the TLV and forward the TLV
to the upstream nodes (see Section 2.4).
4. Section "Security Considerations"
OLD:
This mechanism does not introduce any new weaknesses in LDP. It is
possible to spoof TCP packets belonging to an LDP session to
manipulate the LSP MTU, but LDP has mechanisms to thwart these types
of attacks.
NEW:
This mechanism does not introduce any new weaknesses in LDP. It is
possible to spoof TCP packets belonging to an LDP session to
manipulate the LSP MTU, but LDP has mechanisms to thwart these types
of attacks. See section 5 of [2] for more information on security
aspects of LDP.
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