The MPLS WG Archive

[Paul Billinghurst <pbillinghurst@extremenetworks.com>]

Regarding the scenario discussed in Section 3.5.7.1.4. of RFC 3036 

"The combination of Downstream Unsolicited mode and conservative label
   retention can lead to a situation where an LSR releases the label for
   a FEC that it later needs.  For example, if LSR Rd advertises to LSR
   Ru the label for a FEC for which it is not Ru's next hop, Ru will
   release the label.  If Ru's next hop for the FEC later changes to Rd,
   it needs the previously released label "

The section says the following "To deal with this situation either Ru can
explicitly request the
label when it needs it, or Rd can periodically readvertise it to Ru ".

Does this mean that even though during session initialization Ru stated it
was configured for downstream unsolicited it is allowed to send a label
request message. Have I understood this correctly ? and does this mean the
downstream will accept a request from an upstream router that has signaled
that it is configured for Du ?

The latter mentioned solution i.e. periodically readvertise, is this
inferring periodic label refresh ?

Thanks

Paul