PBX Q-SIG Networking, Access to a Frame Relay Network

Transcription

1 Configuration Note PBX Q-SIG Networking, Access to a Frame Relay Network System Overview This configuration note describes PBX networking with SmartNode devices. It defines SmartNode template configurations, which can be adapted with little effort to the network you want to configure. With the SmartNode products PBX's can be connected with Q-SIG over a data network. Hence an already existing Q-SIG network over dedicated telecom lines can be migrated easily to the data link between the sites and the expensive telecom lines can be saved. In this example the SmartNodes are connected to a Frame-Relay network. Each site has a single physical access but two virtual Frame-Relay circuits one to the remote site the other to the Internet services of the provider. ConfigNote_PBX_QSIG_Networking.doc 1/11

2 Figure 2: Detailed schematics of the complete network ConfigNote_PBX_QSIG_Networking.doc 2/11

3 SmartNodes Figure 3: Schematic of SmartNode configurations ConfigNote_PBX_QSIG_Networking.doc 3/11

4 Session Router Configuration It is assumed that there was a conventional Q-SIG network over dedicated telecom lines between the two sites, which is now migrated to the data link between the sites. An internal numbering plan between both sites exists. E.g. Extension 417 at site A calls extension 605 at site B by simply dialling 605. Assumption: If an extension at one site calls an internal number of an extension at the other site (e.g. 403 calls 655) the PBX routes these calls to its Q-SIG port. Routing (see also figure 3): Calls coming from the Q-SIG port of the PBX (interface QSIG) are directly routed to the link between the sites (interface isoip BackBone). Calls coming from the link between the sites (interface isoip BackBone) are directly routed to the Q-SIG port of the PBX (interface pstn QSIG). Port Configuration The PRI card in slot 1 (port isdn 1 0) is connected to the Q-SIG port of the PBX. Therefore the layer 3 protocol must be set to Q-SIG (l3proto pss1). The UNI type it must be set to 'user' (uni-side usr). The hardware port type for the serial port is set to X.21, the layer 2 protocol is set to Frame-Relay: port serial 0 0 hardware-port x21 encapsulation framerelay Framerelay PVC's: Each site has two virtual Frame-Relay circuits one to the remote site (PVC 87) the other to the Internet services of the provider (PVC 7 for site A, PVC 8 for site B). Fragmentation: Fragmentation has been enabled for the PVC 87 (PVC to the remote site). Fragmentation breaks up every packet larger than the configured fragment size. The purpose is to support real-time and non-real-time packets without causing excessive delays for the real-time data. The fragmentation size depends on the available bandwidth the chosen codec and its packet length: The less bandwidth available per call the smaller the fragment size has to be configured. The shorter the voice packets the smaller the fragment size can be configured. The smaller the fragment size the bigger the overhead for long data packets. The following table shows the minimum fragmentation size depending on the configured codec and its packet length without fragmenting the voice packets: Codec Packet Period [ms] Fragment Size at least [byte] G G G G G G G G G Table 1: Fragmentation Table ConfigNote_PBX_QSIG_Networking.doc 4/11

5 QoS Features To guarantee voice quality under all load conditions QoS features of the SmartWare are configured. For the prioritisation of the voice traffic and call signalling a service-policy profile (VoicePrio), which sets priority to service class local-voice and local-default, is added to the PVC between the sites (context IP interface Remote). All other traffic i.e. the routed traffic (class default) may use the remaining bandwidth. To avoid an overloading of the link a rate limit is set according to the link bandwidth (we assume 2048 Kbits/s). IP Routing The default route of SN_Site_A and SN_Site_B is set statically to the PVC to the Internet: route Internet The route to the own LAN (via the Network Security Device): Site A: route Site B: route The route to the remote LAN is set to the PVC to the remote site: Site A: route Remote Site B: route Remote The route to the remote DMZ is set to the PVC to the remote site: Site A: route Remote Site B: route Remote Fax Fax pass-through method using G.711 is used for fax transmission Synchronisation The packaging of the ISDN voice frames needs a reference clock to avoid clock slips and related voice quality degradations. This reference clock source can be generated internally or derived from one of the ISDN ports. In this example the SmartNodes can be synchronized through the PBX, which is directly connected to the public ISDN. system..clock-source 1 0 port isdn 1 0 clock-mode slave 3 rd Party Equipment PC's Site A: Default Route (Trusted port of the Network Security Device at site A) Site B: Default Route (Trusted port of the Network Security Device at site B) Network Security Device Site A: Default Route (DMZ address of SN_Site_A) Site B: Default Route (DMZ address of SN_Site_B) ConfigNote_PBX_QSIG_Networking.doc 5/11

6 How To Adapt To Your Network IP Addresses LAN: Changing the addresses of the LAN of site A and B the routes to the own and the remote LAN must be modified. DMZ Subnet: Changing the address of the DMZ subnet affects the routing table entry of the SmartNodes to the own LAN, to the remote DMZ and the following sections of the SmartNode configuration: interface DMZ ipaddress <address towards the DMZ> interface isoip BackBone remoteip <DMZ address of the remote SmartNode> Link Bandwidth Within this configuration example we assumed a link bandwidth of 2048 Kbps. For a bandwidth of 768 Kbps the relevant sections within the configuration files of both SmartNodes would look as follows: profile service-policy VoicePrio rate-limit 768 Codecs Using G.729 (best ratio between voice quality and used bandwidth) instead of G.711 (best voice quality but uncompressed) the relevant section within the configuration files of both SmartNodes looks as follows: gateway isoip codec g729 Frame-Relay Interface If your interface to the Frame-Relay backbone is V.35 instead of X.21 you can change it within the serial port configuration: port serial hardware-port v35 PVC's Each permanent virtual circuit is uniquely identified at each Frame-Relay interface by a Data Link Connection Identifier (DLCI). Within this configuration example the assumed DLCI to the remote site is 87, the one to the providers internet services is 7 for site A and 8 for site B. Assigning your DLCI's is done in the PVC configuration mode. The DLCI has to be in the range from 1 to port serial framerelay.. pvc 8.. pvc 87.. ConfigNote_PBX_QSIG_Networking.doc 6/11

7 Complete Configurations SN Site A # # # # Project: Configuration Note PBX Q-SIG Networking, Frame Relay Backbone # Element: SmartNode Site A, SN x IC-E1V # Author: KK # Date: # # # cli version 2.00 system hostname SN_Site_A system clock-source 1 0 profile service-policy VoicePrio rate-limit 2048 mode wfq source class local-voice priority source class local-default priority source class default context ip router interface Remote ipaddress unnumbered use profile service-policy VoicePrio out point-to-point interface Internet ipaddress unnumbered point-to-point interface DMZ ipaddress context ip router route Internet route Remote route Remote ConfigNote_PBX_QSIG_Networking.doc 7/11

8 route multicast-send default-interface Remote context cs switch no number-prefix national no number-prefix international use tone-set-profile default interface pstn QSIG routing dest-interface BackBone bind port 1 0 interface isoip BackBone routing dest-interface QSIG remoteip bind gateway isoip context cs switch gateway isoip codec g711alaw64k 10 use voip-profile default port ethernet 0 1 medium 10 half encapsulation ip bind interface DMZ router port isdn 1 0 down channel-range 0 31 channel-hunting up l2proto pp l3proto pss1 channel-numbering etsi max-channels 30 uni-side usr clock-mode slave up port serial 0 0 shutdown encapsulation framerelay hardware-port x21 framerelay ConfigNote_PBX_QSIG_Networking.doc 8/11

9 no keepalive pvc 7 encapsulation rfc1490 bind interface Internet router pvc 87 encapsulation rfc1490 bind interface Remote router fragment 300 SN Site B # # # # Project: Configuration Note PBX Q-SIG Networking, Frame Relay Backbone # Element: SmartNode Site B, SN x IC-E1V # Author: KK # Date: # # # cli version 2.00 system hostname SN_Site_B system clock-source 1 0 profile service-policy VoicePrio rate-limit 2048 mode wfq source class local-voice priority source class local-default priority source class default context ip router interface Remote ipaddress unnumbered use profile service-policy VoicePrio out point-to-point interface Internet ipaddress unnumbered point-to-point ConfigNote_PBX_QSIG_Networking.doc 9/11

10 interface DMZ ipaddress context ip router route Internet route Remote route Remote route multicast-send default-interface Remote context cs switch no number-prefix national no number-prefix international use tone-set-profile default interface pstn QSIG routing dest-interface BackBone bind port 1 0 interface isoip BackBone routing dest-interface QSIG remoteip bind gateway isoip context cs switch gateway isoip codec g711alaw64k 10 use voip-profile default port ethernet 0 1 medium 10 half encapsulation ip bind interface DMZ router port isdn 1 0 down channel-range 0 31 channel-hunting up l2proto pp l3proto pss1 channel-numbering etsi max-channels 30 uni-side usr clock-mode slave ConfigNote_PBX_QSIG_Networking.doc 10/11

11 up port serial 0 0 shutdown encapsulation framerelay hardware-port x21 framerelay no keepalive pvc 8 encapsulation rfc1490 bind interface Internet router pvc 87 encapsulation rfc1490 bind interface Remote router fragment 300 ConfigNote_PBX_QSIG_Networking.doc 11/11