ch8.pdf

JTO Ph-II (DNIT) BNG 8 BNG 8.1 LEARNING OBJECTIVE In this chapter, we will understand the architecture, functions and implementation of BNG i.e Broadband Network Gateway equipment, w...

JTO Ph-II (DNIT) BNG 8 BNG 8.1 LEARNING OBJECTIVE In this chapter, we will understand the architecture, functions and implementation of BNG i.e Broadband Network Gateway equipment, which is used to establish and manage subscriber sessions. 8.2 INTRODUCTION BNG establishes and manages broadband subscriber sessions. Broadband Network Gateway (BNG) is the access point for subscribers, through which they connect to the broadband network. When a session is active, BNG aggregates traffic from various subscriber sessions from an access network, and routes it to the network of the service provider. BNG is deployed by the service provider and is present at the first aggregation point in the network, such as the Core or Edge Router. When a connection is established between BNG and Customer Premise Equipment (CPE), the subscriber can access the broadband services provided by the Network Service Provide (NSP) or Internet Service Provider (ISP). Because the subscriber directly connects to the edge router, BNG effectively manages subscriber access, and subscriber management functions such as Authentication, authorization and accounting of subscriber sessions, Address assignment, Security, Policy management & Quality of Service (QoS). BNG can be used to provide different network services i.e BNG enables the service provider to customize the broadband package for each customer based on their needs. 8.3 BNG ARCHITECTURE The BNG architecture is designed to perform multiple tasks like: connecting with the Customer Premise Equipment (CPE) that needs to be served broadband services, establishing subscriber sessions using PPPoE protocols, communicating with the AAA server that authenticates subscribers, and keeps an account of subscriber sessions and communicating with the DHCP server to provide IP address to clients. BNG connects to the CPE through Aggregation Switches and DSLAM. DSLAM and aggregation switches sends the aggregated traffic to the BNG. Each subscriber connects to the network by a logical session. Based on the protocol used, subscriber sessions are classified into PPPoE and IPoE sessions. The PPP over Ethernet (PPPoE) subscriber session is established using the point-to-point (PPP) protocol that runs between the CPE and BNG and the IPover Ethernet (IPoE) subscriber session is established using IP protocol that runs between the CPE and BNG. IP addressing is done using the DHCP protocol. BNG relies on an external Remote Authentication Dial-In UserService (RADIUS)server to provide subscriber Authentication, Authorization, and Accounting (AAA) functions. During the AAA process, BNG uses RADIUS to authenticate a subscriber before establishing a subscriber session, authorize the subscriber to access specific network services or resources, track usage of broadband services for accounting or billing. The RADIUS server contains a complete database of all subscribers of a service provider, and provides subscriber data updates to the BNG in the form of attributes within RADIUS messages. BNG, on the other hand, provides session usage (accounting) information to the RADIUS server. BNG can supports connections with more than one RADIUS server to have fail over redundancy in the AAA process. JTO Ph-II Version 3.0 Aug 2021 Page 85 of 103 For Restricted Circulation JTO Ph-II (DNIT) BNG BNG interacts with Dynamic Host Configuration Protocol (DHCP) server for address allocation and client configuration functions. The DHCP server contains an IP address pool, from which it allocates addresses to the CPE or end user PC. BNG can connect to more than one DHCP server to have fail over redundancy in the addressing process. We shall now go through more details of BNG point wise 8.4 REDBACK BNG The modal of REDBACK BNG is SmartEdge. It has the following features:  Redundant Dual Route Processor i.e No Single point of failure for switching,forwarding or route processing.  Redundant power for every slot, redundant cooling  Hot swap for every card  Every card is self-supporting  Every card makes logical routing & switching decisions Figure 50: BNG 8.5 GENERAL SOFTWARE MODEL  Each protocol is a separate process (running on its own protected memory)  Failure of one protocol does not affect other protocols JTO Ph-II Version 3.0 Aug 2021 Page 86 of 103 For Restricted Circulation JTO Ph-II (DNIT) BNG  Protocols can be stopped & restarted individually  Modularity simplifies development & test  Highly modular code is more stable & reliable  Software modularity with restart able protocols improves system & network availability  One module fails, others continue to operate If OSPF crashes? RIB still operates – traffic still flows  Independent stop/restart of each module  Efficient use of system resources. They are allocated to active processes only.  Easier to develop – easier to repair. 8.6 INTER PROCESS COMMUNICATION  Each process talks to each other by using a Redback proprietary version of IPC(standard UNIX inter Process Communications)  Unlike UNIX IPC, Redback IPC connection-oriented(compare between UDP & TCP)  Throttle mechanisms in kernel to adapt to load.  Several ―core‖ processes exists which function like information-hub-and- spoke‖ servers, for example RIB. 8.7 COMMAND LINE INTERFACE The SmartEdge platform can be configured by something called ―Command Line Interface‖  Before you can use the CLI to configure the SmartEdge you need to be connected  Factory default means you can only configure the SmartEdge using the craft port (Console)  On the XCRP there are two craft ports and you need craft port 2 for configuration purposes  Please connect to craft port 2 right now and start your serial terminal (9600, N, 8, 1, no flow control  The Ethernet Port is always slot 7 port 1, even you only have an XCRP in slot 8. JTO Ph-II Version 3.0 Aug 2021 Page 87 of 103 For Restricted Circulation JTO Ph-II (DNIT) BNG  The SmartEdge will always use the Ethernet Port on the active XCRP & use the configuration as applied for slot 7 port 1. 8.8 COMMANDS IN CLI MODE  [local]Redback>  [local]Redback> enable  [local]Redback#  [local]Redback# config  [local]Redback (config)#  [local]Redback (config)# context local  [local]Redback (config-ctx)#  [local]Redback (config-ctx)#interface test  [local]Redback (config-if)#  [local]Redback (config-if)# exit  [local]Redback (config-ctx)#  [local]Redback (config-ctx)# end  [local]Redback # All your commands are stored in transaction datebase But non of your commands are actually activated Activate your configuration  [local]Redback (config)# commit (right away, but do not leave configuration mode)  [local]Redback (config)# end (right away and leave configuration mode)  [local]Redback (config)# exit (only if you jump out of configuration mode)  Throwing your sticky note during configuration: 8.8.1 [local]Redback (config)# abort  Check translation database: 8.8.2 [local]Redback (config)# show translation  Undo a single command: 8.8.3 [local]Redback (config-ctx)# no interface test  While building your configuration using the CLI everything is stored in RAM  RAM is volatile during reloads and thus you will need to store your configuration in non-volatile memory (flash)  Internet storage: Three partitions 8.8.4 Primary boot partition 8.8.5 Alternate boot partition JTO Ph-II Version 3.0 Aug 2021 Page 88 of 103 For Restricted Circulation JTO Ph-II (DNIT) BNG 8.8.6 Configuration files 8.8.7 Device reference: /flash  External storage: 1 Gig microdrive slot 8.8.8 Configuration files 8.8.9 Log files 8.8.10 Device reference: /md  View the active configuration in RAM 8.8.11 [local]Redback# show config  Save the active configuration 8.8.12 [local]Redback#save config [device |url]/filename For Example: 8.8.13 [local]Redback# save config / flash/redback 8.9 MONITORING BOOT SETTINGS When the SmartEdge is going through the system boot sequence, it will check the ―boot configuration‖ parameter.  If the boot configuration parameter is empty it will look for /flash/redback.cfg  If /flash/redback.cfg does not exist, the system will load factory default (empty configuration)  If the boot configuration parameter populated it will use that configuration parameter,for example /flash/newconf.cfg.  Changing the loaded configuration file: [local]Redback# boot configuration Example: [local]Redback# boot configuration / flash / newconf.cfg 8.10 ADMINISTRATOR PRIVACY  Each administrator is treated within the SmartEdge as unique destination for debugging output.  Each administrator can starts its own debugging functionality without influencing other administrators.  Enabling debugging is context specific and requires - [local]Redback# debug (function)  Disabling debugging is context specific and requires - [local]Redback# no debug (function) - [local]Redback# no debug all (Will disable all debug functions in one step) JTO Ph-II Version 3.0 Aug 2021 Page 89 of 103 For Restricted Circulation JTO Ph-II (DNIT) BNG  Disconnecting the telnet / SSH session will be handled as implicit ―no debug all‖ for associated administrator  Debugging is started within a process  Output is sent to ―logger‖ process  Debugging will share the time slice with its own process.  Worse case: its own primary process will slow down and perhaps not respond any more to PM keep alive.  Causing the BSD kernel to restart the process. But most important is, no impact on the traffic card state table 8.11 CONFIGURATION PRINCIPLES  System level configuration 8.11.1 All global parameters: hostname, SNMP, logging, atm, profiles, dot1q profiles and more  Context level configuration 8.11.2 All layer 3 parameters: interfaces, routing, radius, subscriber configuration and more  Port level configuration 8.11.3 Layer 1 & 2 parameters: (no) shutdown, channels, pvc‘s, vlan‘s bindings 8.12 STATIC BINDINGS  For cases where one just need to bind a circuit to an interface we can use a ―static binding‖  The negotiation room has modest role  The operator is responsible for creating and enabling the binding  Typically used for management and backbone connection  Bindings are made from ―outside into the SmartEdge‖:  On ATM pvc you create a binding into the SmartEdge  On Ethernet VLAN you create a binding into the SmartEdge  Bindings are made at the most detailed level available:  Port is least detailed level (Ethernet)  Circuit is most detailed level (ATM PVC, VLAN) JTO Ph-II Version 3.0 Aug 2021 Page 90 of 103 For Restricted Circulation JTO Ph-II (DNIT) BNG  Example of Static binding:  A binding which is configured once by the operator and no subscriber negotiation is required  A fixed binding between circuit and interface on a context  The command syntax is ―bind interface if-name ctx-name‖  Binding are always configured from outside into the SmartEdge on most detailed and unique level possible  Port is least detailed, circuit is most detailed 8.13 ENABLING THE TRAFFIC CARDS  Traffic need to be enabled or configured before they are activated.  This is a feature with several benefits: 8.13.1 Unused traffic cards will not change the working configuration 8.13.2 Saving a working configuration does not include unused cards 8.13.3 Unused traffic cards can be easily put into diagnostic mode  Another benefit: 8.13.4 You can activate a new traffic card without physically installing it 8.13.5 This allows you to create a new configuration including the new Traffic cards as if it is installed. During service window you can insert the new traffic card and the configuration would become active automatically. 8.14 CONCLUSION The BNG architecture is designed to perform multiple tasks. BNG connects to the CPE through Aggregation Switches and DSLAM. DSLAM and aggregation switches sends the aggregated traffic to the BNG. Each subscriber connects to the network by a logical session. Based on the protocol used, subscriber sessions are classified into PPPoE and IPoE sessions. The PPP over Ethernet (PPPoE) subscriber session is established using JTO Ph-II Version 3.0 Aug 2021 Page 91 of 103 For Restricted Circulation JTO Ph-II (DNIT) BNG the point-to-point (PPP) protocol that runs between the CPE and BNG and the IPover Ethernet (IPoE) subscriber session is established using IP protocol that runs between the CPE and BNG. IP addressing is done using the DHCP protocol. JTO Ph-II Version 3.0 Aug 2021 Page 92 of 103 For Restricted Circulation