1、CEPT T/CAC*O13*E 92 = 2326434 0011471 833 W T/CAC 013 E Page 1 Recommendation T/CAC 013 (bu correspondence 1992) QOS IMPROVESLENT OF PSPDK IXTERNATIONAL TRAFFIC IN CEPT Recommendation proposed by the Coordination Group “CXC/BL-S“ Text of the Recommendation adopted bx the Commel-cia1 Actim Committee
2、(CAC): In order to maintain a meaningful level of QOS on the international packet switched service in CEPT countries the fol- lowing actions should be taken: 1. The number of lines installed between two networks should be sufficient to ensure the flou. of international traffic without any perceptibl
3、e difficulties for users. The number of lines in operation should be large enough to avoid an- transit traffic -ia another network for which the resource availabilities are unknown. If more than one line is required for the traffic betxveen two netnorks then one additional link should be installed i
4、n order to cover the failure of one of them. 411 maintenance operations should be transparent for the users. If only one line is sufficient for the traffic between the txo networks. tvhere the averase data throughput is signifi- cant (e.g. 5 Kbps in the busy hour. or the number of lcn 30) then a sec
5、ond line should be put in operation. If the provision of a second line is not implemented. it should be ensured that an automatic back-up routing is available commercially and technically. Back-up routing functions should be implemented in the networks and each additional service ie.g ICL-Gj should
6、be still offered. In any case. back-up routes must be used lvhen very low traffic flovs in order to avoid the owxloading of transit net- works, 2. Each CEPT country using transit relations via another CEPT network should ensure that the transit network secures the route to the destination network. 3
7、. In transit agreements. management priority must be given to request between CEPT countries. 4. A terminal country should accept incoming calls from other CEE countries via any other CEPT nehvork in case of emergency (with the delay for routing acceptance update 1. Any transit network used successf
8、ully in cases of emergency should be systematicall- paid bk- the calling party. according with the CCITT Recommendation D.306R. 5. Each CEP“ country should offer. on each of its public netlvorks a permanently accessible address to allow checks that a route relation is available e.g. echo. drop.). 6.
9、 Effective data throughput should be maintained as high as possible on international relations. -indo- size nego- tiation and packet size negotiation up to 356 octets should be implemented on X.75 international links. 7. The following features should be implemented: - use of TNICs on all CEPT intern
10、ational links. - the PSPDN international accountig sustem should be based on TNICs. - CNICs should be used on all CEPT international links. 8. X.75 Multilink Procedure MLP) operation. o 0 0 Where line quality remains poor. MLP provides high improvement of mean time between call disconnections and sh
11、ould be used. MLP is a solution to avoid that an IPVC is dependent of only one precise SLP and unavailable as soon as the line of this SLP is out of order or under maintenance operation. MLP operation must take in consideration the situation generated by the failure of one SLP: remaining SLPs must not be too much overloaded. A MLP frame not transmitted successfull- by a SLP should be given to another SLP as soon as possible (TI f TI must be short). 0 Edition of December 15. 1992
