TCP/IP Network Administration- P13

Chia sẻ: Thanh Cong | Ngày: | Loại File: PDF | Số trang:50

0
68
lượt xem
19
download

TCP/IP Network Administration- P13

Mô tả tài liệu
  Download Vui lòng tải xuống để xem tài liệu đầy đủ

Tham khảo tài liệu 'tcp/ip network administration- p13', công nghệ thông tin, quản trị mạng phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

Chủ đề:
Lưu

Nội dung Text: TCP/IP Network Administration- P13

  1. [Appendix B] A gated Reference Traces the list of interfaces read from the kernel. Use this to determine what interfaces are detected by the kernel interface scan. The advantage of placing a trace option on the command line is that it can trace activities that happen before the configuration file is processed. For the two options listed above, this is an essential advantage. For other options it is not very important. Most trace options are specified in the configuration file. See the traceoptions command later in this appendix for more details. B.1.1 Signal Processing gated processes the following signals: SIGHUP Tells gated to reread the configuration file. The new configuration replaces the one that gated is currently running. SIGHUP loads the new configuration file without interrupting gated service. SIGHUP is available for quick configuration changes. At most sites, the routing configuration changes infrequently. The few times you need to change to a new configuration, terminate gated and rerun it with the new configuration. This is a more accurate test of how things will run at the next boot. SIGINT Tells gated to snapshot its current state to the file /usr/tmp/gated_dump. SIGTERM Tells gated to shut down gracefully. All protocols are shut down following the rules of that protocol. For example, EGP sends a CEASE message and waits for it to be confirmed. SIGTERM removes from the kernel routing table all routes learned via the exterior routing protocols. If you need to preserve those routes while gated is out of operation, use SIGKILL. SIGKILL Tells gated to terminate immediately and dump core. Routes are not removed from the routing table, and no graceful shutdown is attempted. SIGUSR1 Tells gated to toggle tracing. If no trace flags are set, SIGUSR1 has no effect. But if tracing is enabled, the first SIGUSR1 causes gated to toggle off tracing and to close the trace file. The next SIGUSR1 turns tracing back on and opens the trace file. When the trace file is closed, it can be moved or removed without interfering with the operation of gated. Use this to periodically empty out the trace file to prevent it from becoming too large. SIGUSR2 Tell gated to check for changes in the status of the network interfaces. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_01.htm (3 of 4) [2001-10-15 09:19:11]
  2. [Appendix B] A gated Reference The following is an example of gated signal handling. First, the SIGUSR1 signal is passed to the gated process using the process ID obtained from the gated.pid file (/var/run/gated.pid in this case). # kill -USR1 `cat /var/run/gated.pid` Next, the old trace file (/usr/tmp/gated.log in this case) is removed, and gated is passed another SIGUSR1 signal. # rm /usr/tmp/gated.log # kill -USR1 `cat /etc/gated.pid` After receiving the second signal, gated opens a fresh trace file (still named /usr/tmp/gated.log). An ls shows that the new file has been created. # ls -l /usr/tmp/gated.log -rw-rw-r-- 1 root 105 Jul 6 16:41 /usr/tmp/gated.log Previous: A.3 chat TCP/IP Network Next: B.2 The gated Administration Configuration Language A.3 chat Book Index B.2 The gated Configuration Language [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail Reference | Firewalls | Practical Security ] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_01.htm (4 of 4) [2001-10-15 09:19:11]
  3. [Appendix B] B.2 The gated Configuration Language Previous: B.1 The gated Appendix B Next: B.3 Directive A gated Reference Command Statements B.2 The gated Configuration Language The gated configuration language is a highly structured language similar to C in appearance. Comments either begin with a #, or they begin with /* and end with */. gated configuration statements end with a semicolon, and groups of associated statements are enclosed in curly braces. The language structure is familiar to most UNIX system administrators, and the structure makes it easy to see what parts of the configuration are associated with each other. This is important when multiple protocols are configured in the same file. The configuration language is composed of nine types of statements. Two statement types, directive statements and trace statements, can occur anywhere in the gated.conf file and do not directly relate to the configuration of any protocol. These statements provide instructions to the parser and control tracing from within the configuration file. The other seven statement types are options statements, interface statements, definition statements, protocol statements, static statements, control statements, and aggregate statements. These statements must appear in the configuration file in the correct order, starting with options statements and ending with aggregate statements. Entering a statement out of order causes an error when parsing the file. The remainder of this appendix provides a description of all commands in the gated configuration language, organized by statement type. Previous: B.1 The gated TCP/IP Network Next: B.3 Directive Command Administration Statements B.1 The gated Command Book Index B.3 Directive Statements [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail Reference | Firewalls | Practical Security ] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_02.htm [2001-10-15 09:19:12]
  4. [Appendix B] B.3 Directive Statements Previous: B.2 The gated Appendix B Next: B.4 Trace Statements A gated Reference Configuration Language B.3 Directive Statements Directive statements provide direction to the gated command language parser about "include" files. An include file is an external file whose contents are parsed into the configuration as if it were part of the original gated.conf file. Include files can contain references to other include files, and these references can be nested up to 10 levels deep. The two directive statements are: %include filename Identifies an include file. The contents of the file are "included" in the gated.conf file at the point in the gated.conf file where the %include directive is encountered. filename is any valid UNIX filename. If filename is not fully qualified, i.e., does not begin with a /, it is considered to be relative to the directory defined in the %directory directive. %directory pathname Defines the directory where the include files are stored. When it is used, gated looks in the directory identified by pathname for any include file that does not have a fully qualified filename. Unless you have a very complex routing configuration, avoid using include files. In a complex environment, segmenting a large configuration into smaller, more easily understood segments can be helpful, but most gated configurations are very small. One of the great advantages of gated is that it combines the configuration of several different routing protocols into a single file. If that file is small and easy to read, segmenting the file unnecessarily complicates things. Previous: B.2 The gated TCP/IP Network Next: B.4 Trace Statements Configuration Language Administration B.2 The gated Configuration Book Index B.4 Trace Statements Language Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_03.htm (1 of 2) [2001-10-15 09:19:12]
  5. [Appendix B] B.3 Directive Statements [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail Reference | Firewalls | Practical Security ] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_03.htm (2 of 2) [2001-10-15 09:19:12]
  6. file:///C|/mynapster/Downloads/warez/tcpip/appb_04.htm Previous: B.3 Directive Appendix B Next: B.5 Options A gated Reference Statements Statements B.4 Trace Statements Trace statements allow you to control the trace file and its contents from within the gated.conf file. The trace statement is: traceoptions ["trace_file" [replace] [size bytes[k|m] files n]] [nostamp] trace_options [except trace_options] ; Its components are as follows: trace_file Identifies the file that receives the trace output. It has exactly the same function as the trace_file argument on the gated command line. replace Replaces the existing trace file. If you do not use this keyword, the trace output is appended to the current contents of the file. size bytes[k|m] [files n] Limits the trace file to a maximum size of bytes. The optional k or m indicates thousands (k) or millions (m) of bytes. Thus 1000000 and 10m are equivalent entries. The size of the trace file cannot be less than 10k bytes. n defines the maximum number of trace files that should be saved. When the trace file reaches the maximum size, it is saved as trace_file.0, trace_file.1, trace_file.2 up to trace_file.n. The next save then overwrites trace_file.0. The value for n must be at least 2. nostamp Specifies that trace lines should not begin with a timestamp. Timestamping each line of trace data is the default. trace_options Define the events to be traced by gated. Each trace option is specified by a keyword name. The available trace options are: Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_04.htm (1 of 3) [2001-10-15 09:19:13]
  7. file:///C|/mynapster/Downloads/warez/tcpip/appb_04.htm none Turns off all tracing. all Turns on all types of global tracing. general Turns on both normal and route tracing. state Traces state machine transitions for protocols such as OSPF and BGP. The RFCs describe these protocols using finite state machine (FSM) diagrams or tables. The protocols transition from one state to another based on the occurrence of certain events. For example, the state might change from idle to connect when a connection open event occurs. This is a highly specialized trace flag, useful only to those who have a thorough understanding of the protocols involved. Use this option within the protocol statement to trace a specific protocol's transitions. normal Traces normal protocols interactions. Errors are always traced. policy Traces the application of routing policies. Use this to check that you have properly configured your routing policy. task Traces system-level processing. timer Traces the various timers used by a protocol or peer. route Traces routing table changes. Use this to check that routes are properly installed by the protocol. detail Traces the contents of the packets exchanged by the router. Must be specified before send or recv. send Limits the detail trace to packets sent by this router. recv Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_04.htm (2 of 3) [2001-10-15 09:19:13]
  8. file:///C|/mynapster/Downloads/warez/tcpip/appb_04.htm Limits the detail trace to packets received by this router. Without these two options, all packets are traced when detail is specified. symbols Traces the symbols read from the kernel at startup. See the -t command-line argument. iflist Traces the kernel interface list. See the -t command-line argument. parse Traces the lexical analyzer and parser. adv Traces the allocation and release of blocks. except trace_options Disables specific trace options. Must be used in conjunction with trace_options that enable a wide variety of tracing. For example: traceoptions all except state turns on all traces except for finite state machine tracing. gated provides the flexibility for you to choose where you want to control tracing - on the command line or in the configuration file. By and large, the same trace options can be set on the gated command line or in the configuration file. detail, send and recv can be set only in the configuration file. Two others, symbols and iflist, are primarily used on the command line. Refer to the section on the gated command line for a description of setting trace options with -t. Some trace options are only useful for protocol developers and other experts. For most of us, general, which enables normal and route tracing, is an appropriate level of information for debugging routing problems. Occasionally policy is useful for testing a routing policy. Most of the time, however, no tracing is needed. Previous: B.3 Directive TCP/IP Network Next: B.5 Options Statements Administration Statements B.3 Directive Statements Book Index B.5 Options Statements [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail Reference | Firewalls | Practical Security ] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_04.htm (3 of 3) [2001-10-15 09:19:13]
  9. [Appendix B] B.5 Options Statements Previous: B.4 Trace Appendix B Next: B.6 Interface A gated Reference Statements Statements B.5 Options Statements Options statements define parameters that direct gated to do special internal processing. Options statements appear before any other configuration statements in the gated.conf file. The options statement syntax is: options [nosend] [noresolv] [gendefault [preference preference] [gateway gateway]] [syslog [upto] log_level] [mark time] ; An options statement can contain: nosend Instructs system not to send any packets. This option tests gated without actually sending out routing information. Use for RIP and HELLO. It is not yet implemented for BGP and is not useful for OSPF. noresolv Instructs system not to use the Domain Name System (DNS) to resolve hostnames and addresses. DNS failures can cause gated to deadlock during startup. Use this to prevent deadlock. gendefault [preference preference] [gateway gateway] Generates a default route, with a preference of 20, when gated peers with an EGP or BGP neighbor. If gateway is not defined, the gateway in the generated route is the system itself; the default route is not installed in the kernel table; and it is used only to advertise this system as a default gateway. If gateway is specified, the default route is installed in the kernel table with the specified router as the next hop. This option can be overridden with the nogendefault Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_05.htm (1 of 2) [2001-10-15 09:19:13]
  10. [Appendix B] B.5 Options Statements option. syslog [upto] log_level Tells system to use the setlogmask facility to control gated logging. See the setlogmask(3) manpage if this facility is available on your system. mark time Sends a periodic timestamp message to the trace file. time defines how frequently the timestamp should be issued. Use this to determine if gated is running. Previous: B.4 Trace TCP/IP Network Next: B.6 Interface Statements Administration Statements B.4 Trace Statements Book Index B.6 Interface Statements [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail Reference | Firewalls | Practical Security ] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_05.htm (2 of 2) [2001-10-15 09:19:13]
  11. [Appendix B] B.6 Interface Statements Previous: B.5 Options Appendix B Next: B.7 Definition A gated Reference Statements Statements B.6 Interface Statements An interface statement defines configuration options for the network interfaces. The interface_list identifies the interfaces affected by the configuration options. The interfaces in the list are identified by interface name (e.g., le0), by hostname, by IP address, or by the keyword all. The keyword all refers to every interface on the system. The interface name can refer to a single interface or a group of interfaces. For example, an interface name of eth0 refers to the interface eth0, whereas the name le refers to all installed interfaces that start with the letters le (which might include le0, le1, and le2). A hostname can be used if it resolves to only one address. Most system administrators prefer to use the IP address to identify an interface. After all, IP addresses are inherently a part of TCP/IP, and it's TCP/IP routing that this file configures. Additionally, remote systems know this interface by its IP address, not its interface name. Finally, DNS may provide more than one address for a hostname, and future UNIX operating systems may allow more than one address per interface. IP addresses are safest. gated supports four types of interfaces: loopback, broadcast, point-to-point, and non-broadcast multi- access (NBMA). All of these are discussed in the text of this book except for NBMA. It is a multi- access interface, but the underlying network is not capable of broadcast. Examples are frame relay and X.25. gated ignores any interface in the list that has an invalid local, remote, or broadcast address, or an invalid subnet mask. gated also ignores a point-to-point interface that has the same local and remote addresses. gated assumes that interfaces that are not marked UP by the kernel do not exist. The syntax of the interfaces statement is: interfaces { options [strictinterfaces] [scaninterval time] ; interface interface_list [preference preference] [down preference preference] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_06.htm (1 of 3) [2001-10-15 09:19:14]
  12. [Appendix B] B.6 Interface Statements [passive] [simplex] [reject] [blackhole] ; define address [broadcast address] | [pointtopoint address] [netmask mask] [multicast] ; }; The configuration options defined before the interface list are global options. The global options are: strictinterfaces Generates a fatal error if an interface is referenced in the configuration file that is not found when gated scans the kernel at startup and is not listed in a define statement. (See the define option later in this section.) Normally a warning message is issued and gated continues running. scaninterval time Specifies how often gated scans the kernel interface list for changes. The default is every 15 seconds on most systems, and 60 seconds on systems that pass interface status changes through the routing socket, e.g., BSD 4.4. Note that gated also scans the interface list on receipt of a SIGUSR2. The interface command defines the interface_list and all of the options that affect the specified interfaces. Options available on this statement are: preference preference Sets the preference for this interface. The value preference is a number between 0 and 255. gated prefers routes through interfaces with low preference numbers. The default preference for all directly attached network interfaces is 0. down preference preference Sets the preference used when gated believes an interface is not functioning properly. The default is 120. passive Prevents gated from downgrading the preference of the interface when it is not functioning properly. gated assumes that an interface is down when it stops receiving routing information through that interface. gated only performs this check if the interface is actively participating in a routing protocol. simplex Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_06.htm (2 of 3) [2001-10-15 09:19:14]
  13. [Appendix B] B.6 Interface Statements Specifies that gated should not use packets generated by this system as an indication that the interface is functioning properly. Only packets from remote systems are used to indicate that the interface is operating. reject | blackhole Either of these keywords identifies the interface as the "blackhole interface" used to install rejected routes in the kernel. (See the control statements for more about rejected routes.) This is available only on BSD systems that have installed a reject/blackhole pseudo-interface. The define address command lists interfaces that might not be present when gated scans the kernel interface list at startup. It overrides the strictinterfaces option for the interface defined by address. Possible options for the define command are: broadcast address Defines the broadcast address. pointopoint address Defines the local address for a point-to-point interface. (See Chapter 6, Configuring the Interface for a discussion of point-to-point interfaces.) When this option is used, the address on the define statement specifies the address of the remote host, and the address specified after the pointopoint keyword defines the local address. Don't use both broadcast and pointopoint in the same define. netmask mask Defines the subnet mask. multicast Specifies that the interface supports multicasting. Previous: B.5 Options TCP/IP Network Next: B.7 Definition Statements Administration Statements B.5 Options Statements Book Index B.7 Definition Statements [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail Reference | Firewalls | Practical Security ] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_06.htm (3 of 3) [2001-10-15 09:19:14]
  14. [Appendix B] B.7 Definition Statements Previous: B.6 Interface Appendix B Next: B.8 Protocol A gated Reference Statements Statements B.7 Definition Statements Definition statements are general configuration statements that relate to more than one protocol. Definition statements must appear before any protocol statements in gated.conf. The three definition statements are: autonomoussystem asn [loops n] ; Defines the autonomous system number (asn) used by BGP or EGP. The loops number defines the number of times this autonomous system may appear in an AS path for path vector protocols, such as BGP. The default value for n is 1. routerid address ; Defines the router identifier used by BGP and OSPF. Use the address of your primary OSPF or BGP interface. By default, gated uses the address of the first interface it encounters. martians { host address [allow]; address [mask mask | masklen number] [allow] ; default [allow] ; }; Changes the list of addresses about which all routing information is ignored. Sometimes a misconfigured system sends out obviously invalid destination addresses. These invalid addresses, called martians, are rejected by the routing software. This command allows changes to the list of martian addresses. A martian address can be specified as a host address by using the host keyword before the address, or as a network address by simply specifying the address. An address mask can be defined for a network address. The mask can be defined in dotted decimal notation using the mask keyword or as a numeric prefix length using the masklen keyword. The address masks mask 255.255.0.0 and masklen 16 are equivalent. If no address mask is specified, the natural mask is used. Specifying an address in the martians statement adds the address to the martians list. The allow keyword is used to remove an address from the martians list. When an address is removed from the martians list, it then becomes a valid address for routing. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_07.htm (1 of 2) [2001-10-15 09:19:14]
  15. [Appendix B] B.7 Definition Statements gated contains a standard martian list of addresses that are known to be invalid. This is the default martian list. The option default allow removes all of the standard entries from the martians list and permits unrestricted routing. Don't do this if you're on a connected network. Here is a sample of each definition statement: autonomoussystem 249 ; routerid 172.16.12.2 ; martians { host 0.0.0.26 ; 192.168.0.0 masklen 16 allow ; } ; The statements in the sample perform the following functions: q The autonomoussystem statement tells gated to use AS number 249 for its BGP or EGP packets. q The routerid statement tells gated to use 172.16.12.2 as the router identifier for OSPF and BGP. q The martians statement prevents routes to 0.0.0.26 from being included in the table, but it allows routes to the private IP addresses in the range 192.168.0.0 to 192.168.255.255. Previous: B.6 Interface TCP/IP Network Next: B.8 Protocol Statements Administration Statements B.6 Interface Statements Book Index B.8 Protocol Statements [ Library Home | DNS & BIND | TCP/IP | sendmail | sendmail Reference | Firewalls | Practical Security ] Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_07.htm (2 of 2) [2001-10-15 09:19:14]
  16. [Appendix B] B.8 Protocol Statements Previous: B.7 Definition Appendix B Next: B.9 static Statements A gated Reference Statements B.8 Protocol Statements Protocol statements enable or disable protocols and set protocol options. The protocol statements occur after the definition statements and before the static statements. There are many protocol statements and more may be added at any time. There are statements for the various interior and exterior routing protocols, and for other things that are not really routing protocols. In this section we begin with the interior protocols, move on to the exterior protocols, and finish with the special "protocols." B.8.1 The ospf Statement ospf yes | no | on | off [{ defaults { preference preference ; cost cost ; tag [as] tag ; type 1 | 2 ; } ; exportlimit routes ; exportinterval time ; traceoptions trace_options ; monitorauthkey password ; backbone | area number { authtype 0 | 1 | none | simple ; stub [cost cost] ; networks { address [mask mask |masklen number] [restrict] ; host address [restrict] ; } ; stubhosts { address cost cost ; } ; interface interface_list [nonbroadcast] [cost cost] { pollinterval time ; routers { address [eligible] ; } ; interface_parameters } ; Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_08.htm (1 of 26) [2001-10-15 09:19:17]
  17. [Appendix B] B.8 Protocol Statements virtuallink neighborid router_id transitarea area { interface_parameters } ; }; }]; The ospf statement enables or disables the Open Shortest Path First (OSPF) routing protocol. By default, OSPF is disabled. It is enabled by specifying yes or on (it doesn't matter which you use) and it is disabled with no or off. NOTE: For the sake of brevity, this text explains only the first occurrence of any gated.conf parameter if it is used the same way in subsequent commands. Only differences between commands are explained. For example, yes | no | on | off is not explained again, because it is always used in the same way to enable or disable a protocol. The ospf statement has many configuration parameters: defaults Defines the defaults used when importing OSPF routes from an external autonomous system and announcing those routes to other OSPF routers. The link-state advertisement (LSA) used to announce these routes is called an ASE (autonomous system external) because it contains routes from external autnomous systems. See the description of OSFP in Chapter 7. preference preference Defines the preference of OSPF ASE routes. The default is 150. cost cost Defines the cost used when advertising a non-OSPF route in an ASE. The default is 1. tag [as] tag Defines the OSPF ASE tag value. The tag is not used by the OSPF protocol, but may be used by an export policy to filter routes. (See the export statement later in this appendix.) When the as keyword is specified, the tag field may contain AS path information. type 1 | 2 Defines the type of ASE used. The default is type 1. Type 1 contains routes learned from an external protocol that provides a metric directly comparable to the OSPF metric. The metric is added to the cost of reaching the border router when routes are advertised. A type 2 ASE contains routes learned from an exterior gateway protocol that does not provide a routing metric comparable to the OSPF metric. These routes are advertised with the cost of reaching the border router. See Chapter 7. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_08.htm (2 of 26) [2001-10-15 09:19:17]
  18. [Appendix B] B.8 Protocol Statements exportlimit routes Defines the maximum number of ASE LSAs that will be flooded at one time. The default is 100. exportinterval time Defines how frequently ASE link-state advertisements are flooded to the network. The default is once per second. traceoptions trace_options Defines the tracing used to debug OSPF. In addition to the standard trace flags, OSPF supports: lsabuild Traces construction of link-state advertisements (LSA). spf Traces the Shortest Path First (SPF) calculations. hello Traces the OSPF HELLO packets. dd Traces the OSPF Database Description packets. request Traces the OSPF Link-State Request packets. lsu Traces the OSPF Link-State Update packets. ack Traces OSPF Link-State Ack packets. monitorauthkey password Defines the password used for ospf_monitor queries. By default these queries are not authenticated. If monitorauthkey is specified, incoming queries must contain the specified password. backbone | area number Defines the OSPF area of which this router is a member. Every router must belong to an area. If more than one area is configured, at least one must be the backbone. The backbone is defined using the backbone keyword. All other areas are defined by the area keyword and the number Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_08.htm (3 of 26) [2001-10-15 09:19:17]
  19. [Appendix B] B.8 Protocol Statements of the area, e.g., area 1. See Chapter 7 for a discussion of OSPF areas. Several configuration parameters are associated with each area: authtype 0 | 1 | none | simple Specifies the authentication scheme used in this area. The authentication schemes can be defined by none or 0 for no authentication, or simple or 1 for password authentication. Each system in an area must use this same authentication scheme. stub [cost cost] Specifies that this is a stub area. A stub area is one in which there are no ASE routes. If a cost is specified, it is used to advertise a default route into the stub area. networks Defines the range of networks contained within this area. The specified ranges are advertised into other areas as summary network LSAs and not as inter-area routes. If restrict is specified, the summary network LSAs are not advertised. The entries in the networks list are either specified as host addresses by using the host keyword before the address, or as a network address by simply specifying the address. An address mask can be defined for a network address. The mask can be defined in dotted decimal notation using the mask keyword or as a numeric prefix length using the masklen keyword. The address masks mask 255.255.0.0 and masklen 16 are equivalent. If no address mask is specified, the natural mask is used. This option can reduce the amount of routing information propagated between areas. stubhosts Lists the directly attached hosts, and their costs, that should be advertised as reachable from this router. List point-to-point interfaces here. interface interface_list [nobroadcast] [cost cost] Defines the interfaces used by OSPF. If the keyword nobroadcast is specified, the interface connects to a non-broadcast multi-access (NBMA) network. If nobroadcast is not used, the interface connects to a broadcast or a point-to-point network. Specify the cost of the interface with the cost keyword, e.g., cost 5. The default cost is 1. Two options are specific to NBMA interfaces: pollinterval time Defines the time interval at which OSPF HELLO packets are sent to neighbors. routers Lists all neighbors by address. The eligible keyword indicates if the neighbor can become a designated router. Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_08.htm (4 of 26) [2001-10-15 09:19:17]
  20. [Appendix B] B.8 Protocol Statements Point-to-point interfaces have one additional parameter: nomulticast Forces gated to unicast OSPF packets over this interface. By default, OSPF packets to neighbors on point-to-point interfaces are sent via the IP multicast mechanism. Use this option if the remote neighbor does not support multicasting. All interfaces - NBMA, point-to-point, and broadcast - can use these parameters: enable | disable ; Enables or disables the interface. retransmitinterval time ; Defines the number of seconds between link-state advertisement retransmissions. transitdelay time ; Defines the estimated number of seconds required to transmit a link-state update over this interface. It must be greater than 0. priority priority ; Defines this system's priority for the designated router election. priority is a number from 0 to 255. The router with the highest priority becomes the designated router. A router whose priority is 0 is ineligible to become the designated router. See Chapter 7 for a discussion of desginated routers. hellointerval time ; Defines the number of seconds between transmissions of HELLO packets. routerdeadinterval time ; Defines the timeout before a neighbor is declared down. time is the maximum number of seconds this router will wait for a neighbor's Hello packet. authkey key ; Defines a key used to authenticate OSPF packets. The key is specified as one to eight decimal digits separated by periods, a one- to eight-byte hexadecimal string preceded by 0x, or a one- to eight-character string in double quotes. virtuallink neighborid router_id transitarea area Defines a virtual link for the backbone area. The router_id is the router identifier of the remote router at the other end of the virtual link. The transit area must be one of the other areas configured on this system. All standard interface parameters defined above may be specified on Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark. file:///C|/mynapster/Downloads/warez/tcpip/appb_08.htm (5 of 26) [2001-10-15 09:19:17]
Đồng bộ tài khoản