[Isis-wg] comment on draft-ietf-isis-segment-routing-extensions-02

[Chris Bowers <[e-mail]>]

All,

The current text of draft-ietf-isis-segment-routing-extensions-02 does not clearly explain the usage of the Binding TLV for advertising LSPs created using other protocols.  I would like to propose the following text to be included as section 2.5 .

Thanks,
Chris

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2.5 Binding TLV usage examples

This section gives examples of using the Binding TLV to advertise SID/label bindings associated with RSVP-TE, LDP, and BGP labeled-unicast LSPs.  It also includes an example of advertising a context-id for egress node protection.  All of the examples assume that the Binding TLV weight=1 and metric=100.

2.5.1 Advertising an RSVP-TE LSP using the Binding TLV

Assume that R1 has signaled an RSVP-TE LSP to egress router (R4) with router-id=10.4.4.4, with ER0 = (192.1.2.2 [strict], 192.2.3.2 [strict], 192.3.4.2 [strict]). R1 can advertise a locally significant label binding for this LSP (with label value=1099)  using the following values and sub-TLVs in the Binding TLV.

Binding-TLV: F-bit=0, M-bit=0, weight=1, range=1, prefix length=32, FEC prefix=10.4.4.4
SID/Label Sub-TLV: label=1099
ERO Metric sub-TLV: metric=100
IPv4 ERO sub-TLV: L-bit=0, IPv4 address=192.1.2.2
IPv4 ERO sub-TLV: L-bit=0, IPv4 address=192.2.3.2
IPv4 ERO sub-TLV: L-bit=0, IPv4 address=192.3.4.2

2.5.2 Advertising an LDP LSP using the Binding TLV

Assume that R5 has learned a FEC-label binding via LDP for FEC=10.8.8.8/32.  R5 can advertise a locally significant label binding for this LSP (with label value=5099) using the following values and sub-TLVs in the Binding TLV.

Binding TLV: F-bit=0, M-bit=0, weight=1, range=1, prefix length=32, FEC prefix=10.8.8.8
SID/Label Sub-TLV: label=5099
ERO Metric sub-TLV: metric=100
IPv4 ERO sub-TLV: L-bit=1, IPv4 address=10.8.8.8

2.5.3 Advertising a BGP labeled-unicast LSP using the Binding TLV

Assume that R9 has used BGP labeled-unicast to learn a label binding for prefix 10.15.15.15/32 with BGP next-hop=10.12.12.12.   R9 can advertise a locally significant label binding for this LSP (with label value=7099)  using the following values and sub-TLVs in the Binding TLV.

Binding-TLV: F-bit=0, M-bit=0, weight=1, range=1, prefix length=32, FEC prefix=10.15.15.15
SID/Label Sub-TLV: label=7099
ERO Metric sub-TLV: metric=100
IPv4 ERO sub-TLV: L-bit=1, IPv4 address=10.12.12.12

2.5.4 Advertising a context-id for egress node protection using the Binding TLV

Assume that R22 is configured in the protector role to provide egress node protection for R21 using context-id=10.0.0.21.  R22 can advertise the label associated with this context-id (with label value=8099) using the following values and sub-TLVs in the Binding TLV.

Binding TLV: F-bit=0, M-bit=1, weight=1, range=1, prefix length=32, FEC prefix=10.0.0.21 SID/Label Sub-TLV: label=8099

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