I support (1).
As explained by Trowbridge and Juergen, despite small possible differences in some header fields, SDH and SONET do interwork. Paths do cross from SONET domains to SDH domains - with variable degrees of gateworking required (and often none). It is thus not appropriate to classify the path as SONET or SDH. It is more convenient to have single label scheme.
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Lionel Silman, Ph.D. System Design Director
Enavis Networks
16, Martin Gehl Street, Petach Tikva 49194 Israel
Work:+972(3)9261537 Fax: +972(3)9261845
Home:+972(3)6417464 Email:LionelS@enavis.com