[Idr] draft-ietf-idr-segment-routing-te-policy Policy Name Sub-TLV considerations
Jeffrey Haas <jhaas@pfrc.org> Wed, 12 February 2020 23:11 UTC
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Date: Wed, 12 Feb 2020 18:17:12 -0500
From: Jeffrey Haas <jhaas@pfrc.org>
To: draft-ietf-idr-segment-routing-te-policy@ietf.org, idr@ietf.org
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Subject: [Idr] draft-ietf-idr-segment-routing-te-policy Policy Name Sub-TLV considerations
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Authors, In draft-ietf-idr-segment-routing-te-policy-08, Section 2.4.6 we have a TLV for Policy Name. Its text is: : 2.4.6. Policy Name Sub-TLV : : An operator MAY set the Policy Name sub-TLV to attach a symbolic name : to the SR Policy candidate path. : : Usage of Policy Name sub-TLV is described in section 2 in : [I-D.ietf-spring-segment-routing-policy]. : : The Policy Name sub-TLV may exceed 255 bytes length due to long : policy name. Therefore a 2-octet length is required. According to : [I-D.ietf-idr-tunnel-encaps], the first bit of the sub-TLV codepoint : defines the size of the length field. Therefore, for the Policy Name : sub-TLV a code point of 128 or higher is used. : : The Policy Name sub-TLV is optional and it MUST NOT appear more than : once in the SR Policy TLV. : : The Policy Name sub-TLV has following format: : : 0 1 2 3 : 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : | Type | Length | RESERVED | : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : // Policy Name // : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : Where: : : Type: 129. : : Length: Variable. : : RESERVED: 1 octet of reserved bits. SHOULD be set to zero on : transmission and MUST be ignored on receipt. : : Policy Name: Symbolic name for the policy. It SHOULD be a string : of printable ASCII characters, without a NULL terminator. draft-ietf-spring-segment-routing-policy-06, Section 2.1 discusses this Sub-TLV: : An implementation MAY allow assignment of a symbolic name comprising : of printable ASCII characters to an SR Policy to serve as a user- : friendly attribute for debug and troubleshooting purposes. Such : symbolic names may identify an SR Policy when the naming scheme : ensures uniqueness. There are two observations I'd like to make: 1. A 65K length isn't very likely in BGP. :-) I suggest that greater guidance for shorter names should be offered. For example, perhaps limit the length to 1K. Alternatively, offer advice such as: "Implementations may choose to truncate long Policy Names". 2. The guidance about "printable ASCII" is rather old-style and likely to run askance of IESG review for internationalization considerations. I'd suggest that the field be encoded in UTF-8 and make reference to print-safety similar to RFC 8203 (BGP Administrative Shutdown) in its Security Considerations. -- Jeff
- [Idr] draft-ietf-idr-segment-routing-te-policy Po… Jeffrey Haas
- Re: [Idr] draft-ietf-idr-segment-routing-te-polic… Ketan Talaulikar (ketant)
- Re: [Idr] draft-ietf-idr-segment-routing-te-polic… Ketan Talaulikar (ketant)
- Re: [Idr] draft-ietf-idr-segment-routing-te-polic… Andrew Alston
- Re: [Idr] draft-ietf-idr-segment-routing-te-polic… Nandan Saha
- Re: [Idr] draft-ietf-idr-segment-routing-te-polic… bruno.decraene
- Re: [Idr] draft-ietf-idr-segment-routing-te-polic… Ketan Talaulikar (ketant)