I would word it like this:
"...The current LDAP version is LDAPv3, as defined in <ulink url="http://tools.ietf.org/html/rfc4510">RFC4510</ulink>, and the implementation in Ubuntu is OpenLDAP."
I would word it like this:
"...The current LDAP version is LDAPv3, as defined in <ulink url="http:// tools.ietf. org/html/ rfc4510">RFC4510</ulink>, and the implementation in Ubuntu is OpenLDAP."