Itu telecommunication Standardization Sector Temporary Document xxx(plen) study group 15
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III.3.2.2 OSI Only Gateway NEOccasionally automatically encapsulating nodes will be used to upgrade an existing OSI-only area to make it effectively into a dual area. In this case the gateway nodes may have to remain as OSI-only nodes. In such a case a network can be built as shown in Figure III-9. 
Figure III-9 In this network the CLNP packets that need to leave the level-1 area continue to go to the OSI level-1,level-2 router. The nodes that have a manual tunnel leading out of the level-1 area advertise this as a default route. Consequently the IP-capable nodes will all add an entry to the bottom of their routing table telling them to send all IPv4 packets to one of the nodes that has the manual tunnel, unless they have a more specific route. In this way an IPv4 packet is never sent to a level-1,level-2 node, but is always sent across one of the manual tunnels. The router in the Access DCN that terminates the manual tunnel does not need to run Integrated IS-IS. It may run any IP routing protocol that an operator wishes to use. In this way an existing network that uses OSPF and level-2 IS-IS in the Access DCN, and level-1 IS-IS in the SDH NEs may have the level-1 areas upgraded to dual areas with little impact on the existing OSI-only SDH NEs or on the Access DCN.
APPENDIX IV Bibliography (This Appendix does not form an integral part of this Recommendation) IETF RFC 1006 – ISO Transport Service on top of the TCP Version: 3 – May 1997 IETF RFC 2966 – Domain-wide Prefix Distribution with Two-Level IS-IS – October 2000 IETF RFC 3147 – Generic Routing Encapsulation of CLNS Networks – July 2001 ______________ Directory: lib lib -> Security Survey lib -> Strategic Plan South Sudan Country Office Context lib -> The World Order of Bahá’u’lláh Selected Letters lib -> 1. naclo 2015 – North American Computational Linguistics Olympiad lib -> Ieee/iee electronic Library (iel) lib -> Lnpa wg position on Porting of Telephone Numbers Used by Voip service Providers lib -> 1. naclo 2017 – North American Computational Linguistics Olympiad lib -> [0] B. Hardware [2] lib -> [1] B. Hardware [1] lib -> Chem I honors Unit 2 Notes: Numbers in Chemistry Measurement Download 0.91 Mb. Share with your friends:
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