Re: [Isis-wg] questions about draft-ietf-idr-ls-distribution-11

[Hannes Gredler <[e-mail]>]

hi peng,

On Thu, Jul 02, 2015 at 10:13:57AM +0800, [e-mail] wrote:
|    hi hannes & other authors
| 
|    As described in [Link-State Info Distribution using BGP] (see Section
|    3.2.2, ¡°Link Descriptors¡±), the IP address TLVs (TLV code 259-262) or
|    the link local/remote Identifier TLV (TLV code 258) are included in the
|    link descriptor.
|    ¡°The information about a link present in the LSA/LSP originated by the
|    local node of the link determines the set of TLVs in the Link Descriptor
|    of the link.
|          If interface and neighbor addresses, either IPv4 or IPv6, are
|    present, then the IP address TLVs are included in the link descriptor, but
|    not the link local/remote Identifier TLV.  The      link local/remote
|    identifiers MAY be included in the link attribute.
|          If interface and neighbor addresses are not present and the link
|    local/remote identifiers are present, then the link local/remote
|    Identifier TLV is included in the link descriptor.¡±
| 
|    When the underlying IGP is IS-IS, LSP originated by the local node of the
|    link MAY NOT include IPv4 interface address/IPv4 neighbor address or Link
|    Local/Remote Identifiers sub-TLV in the (main) IS reachability TLV when
|    MPLS Traffic Engineering is not configured for IS-IS (see Section 3.2,
|    ¡°Sub-TLV 6: IPv4 Interface Address¡±, of [RFC5305] and Section 1.1,
|    ¡°Link Local/Remote Identifiers¡±, of [RFC5307], respectively).
| 
|    Thus, BGP-LS speaker MAY learn the mentioned link information, from LSP
|    flooding process, without detailed interface IP/ID information of all IGP
|    nodes in the BGP-LS domain.  If CONSUMER collect link-state information of
|    whole domain only from one BGP-LS speaker, it can only establish one SPT ,
|    which root is the BGP-LS speaker. In some case, CONSUMER need create
|    different SPT for different device. For example, in central spring
|    network, the CONTROLLER need download ILM entry for a global label to each
|    router, the ILM forwarding information is decided by each router's SPT. It
|    is different for different router.
| 
|    some solutions could be:
|    1) all IGP nodes in the BGP-LS domain are BGP-LS speakers, where only
|    local link information need to be collected and sent to CONSUMER.
|    2) one BGP-LS speaker, but all link are configured MPLS Traffic
|    Engineering(not certainly including signal configuration).
| 
|    Do you have any suggestions about this issue?

i'd be in favour of 1) - /hannes