Using the OSPF Protocol
This document describes the Open Shortest Path First (OSPF) Protocol, which is an Interior Gateway Protocol (IGP). The router supports two IGPs, OSPF and RIP.
OSPF is based on link-state technology or the shortest-path first (SPF) algorithm. RIP is based on the Bellman-Ford or the distance-vector algorithm.
This document contains the following sections:
The OSPF Routing Protocol
Configuring OSPF
OSPF Commands
Routers that use a common routing protocol form an autonomous system (AS). This common routing protocol is called an Interior Gateway Protocol (IGP). IGPs dynamically detect network reachability and routing information within an AS and use this information to build the IP routing table. IGPs can also import external routing information into the AS.
OpenROUTE Networks routers can simultaneously run OSPF and RIP. When doing so, OSPF routes are preferred. In general, use of the OSPF protocol is recommended due to its robustness, responsiveness, and decreased bandwidth requirements.
The OSPF Routing Protocol
OpenROUTE supports a complete implementation of the OSPF routing protocol, as specified in RFC 1247 (Version 2). This version is incompatible with routers running OSPF version 1. OSPF information is not exchanged between routers running version 1 and version 2.
OSPF is a link state dynamic routing protocol that detects and learns the best routes to (reachable) destinations. OSPF can quickly perceive changes in the topology of an AS, and after a short convergence period, calculate new routes. The OSPF protocol does not encapsulate IP packets, but forwards them based on destination address only.
Configuring OSPF Over Frame Relay
OSPF over Frame Relay is referred to as Point-to-Multipoint (listed as P-2-MP in the OSPF monitoring environment).
To configure OSPF over Frame Relay, do the following
- 1. Assign a single IP subnet to the entire cloud.
- 2. Assign a single IP address to each Frame Relay interface (regardless of the PVCs configuration).
- 3. Use the set interface command to enable OSPF over Frame Relay. (Do not use the set non-broadcast command.)
- 4. Use the add neighbor command on one side of each PVC so that the routers can communicate.
- Note:
In a star configuration, use the add neighbor command at the hub (neighbors at the remote site do not need to be configured). The add neighbor command takes effect immediately without restarting the router.
OSPF provides services not available with RIP. OSPF features include the following:
OSPF supports the following physical network types:
Configuring OSPF
The following steps outline the tasks required to get the OSPF protocol up and running. The sections that follow explain each step in detail, including examples.
- 1. Enable OSPF. In doing so, you must estimate the final size of the OSPF routing domain.
- 2. Define OSPF areas attached to the router. If you do not define OSPF areas, the router assumes there is a single backbone area.
- 3. Define the router's OSPF network interfaces. Set the cost of sending a packet out each interface, along with a collection of OSPF operating parameters.
- 4. If you want to forward IP multicasts (IP Class D addresses), enable IP multicast routing capability.
- 5. If the router connects to non-broadcast networks, set the non-broadcast network parameters. This consists of a list of the other OSPF routers that are connected to the non-broadcast network.
- 6. If you want the router to import routes learned from other routing protocols (EGP, RIP or statically configured routes), enable AS boundary routing. In addition, you must define whether routes are imported as Type 2 or Type 1 externals.
- 7. If you want to boot a neighboring router over an attached point-to-point interface, configure the neighbor's IP address. This is done by defining non-broadcast parameters for the point-to-point interface.
Enabling the OSPF Protocol
Before you can enable OSPF, you must supply the total number of external routes and the total number of OSPF routers. These values estimate the final size of the OSPF routing domain and should be identical in all of your OSPF routers. Each router running OSPF has a database describing a map of the routing domain. This database is identical in all participating routers. From this database, the router builds the IP routing table through the construction of a shortest-path tree, with the router itself as root. The routing domain refers to an AS running the OSPF protocol.
To enable OSPF enter enable ospf and respond to the prompts:
OSPF Config>enable ospf
Estimated # external routes[0]? 200
Estimated # OSPF routers [0]? 60
Defining Backbone and Attached OSPF Areas
Define the OSPF areas that are directly attached to the router. If you do not define any areas, the software assumes that all of the router's directly attached networks belong to the backbone area (area ID 0.0.0.0).
OSPF allows you to split the AS into regions called areas. OSPF areas are a collection of contiguous networks. The topology of any one area is hidden from that of the other areas. Hiding information significantly reduces routing traffic and protects routing within an area from outside influence.
A router has a separate database that contains the topology for each area to which it is connected. Two routers belonging to the same area have identical topologies for that area.
OSPF areas are defined as address ranges. External to the area, a single route is advertised for each address range. For example, if an OSPF area consists of all subnets of the class B network 128.185.0.0, the area consists of a single address range. The address range is specified as an address of 128.185.0.0 together with a mask of 255.255.0.0. Outside the area, the entire subnetted network is advertised as a single route to network 128.185.0.0.
Every OSPF routing domain must have a backbone. The backbone is a special OSPF area having an area ID equal to 0.0.0.0. The OSPF backbone must be contiguous; however, it is possible to define areas where the backbone is not physically contiguous. When this situation exists, you must configure a virtual link to maintain the backbone's connectivity. You can configure virtual links between any two backbone routers that have an interface to a common non-backbone area.
Figure 1 OSPF Areas
The backbone is responsible for distributing inter-area routing information. The backbone area consists of any of the following:
To set the parameters for an OSPF area, use the set area command:
OSPF Config> set area
Area number [0.0.0.0]? 0.0.0.1
Authentication type [1]? 1
Is this a stub area? (Yes or No): no
Setting OSPF Interfaces
To set the OSPF parameters for the router's network interfaces, use the set interface command, then respond to the prompts.
You can dynamically change the cost of an OSPF interface from the router's monitoring environment. This new cost is flooded quickly throughout the OSPF routing domain, and modifies the routing immediately. When you restart/reload the router, the cost of the interface reverts to the value in the saved configuration.
There are two special kinds of OSPF routers, area border routers and AS boundary routers.
OSPF Routing Summary
When a router is initialized, it uses the Hello Protocol to send hello packets to its neighbors, and they in turn send their packets to the router. On broadcast and point-to-point networks, the router dynamically detects its neighboring routers by sending the Hello packets to the multicast address ALLSPFRouters; on non-broadcast networks you must configure information to help the router discover its neighbors. On all multi-access networks (broadcast and non-broadcast), the Hello Protocol also elects a designated router for the network.
The router then attempts to form adjacencies with its neighbors to synchronize their topological databases. Adjacencies control the sending and receiving of the routing protocol packets, as well as the distribution of the topological database updates. On a multi-access network, the designated router determines which routers become adjacent.
A router periodically advertises its status or link state to its adjacencies. Link state advertisements flood throughout an area ensuring that all routers have exactly the same topological database. This database is a collection of the link state advertisements received from each router belonging to an area. From the information in this database, each router can calculate a shortest path tree with itself designated as the root. Then the shortest path tree generates the routing table.
Designated Router
Every multi-access network has a designated router that performs two main functions for the routing protocol, it originates network link advertisements and it becomes adjacent to all other routers on the network.
When a designated router originates network link advertisements, it lists all the routers, including itself, currently attached to the network. The link ID for this advertisement is the IP interface address of the designated router. By using the subnet/network mask, the designated router obtains the IP network number.
The designated router becomes adjacent to all other routers and is tasked with synchronizing the link state databases on the broadcast network.
The Hello Protocol elects the designated router after determining the router's priority from the Rtr Pri field of the hello packet. When a router's interface first becomes functional, it checks to see if the network currently has designated router. If it does, it accepts that designated router regardless of that router's priority, otherwise, it declares itself the designated router. If the router declares itself the designated router at the same time another router does, the router with highest router priority (Rtr Pri) becomes the designated router. In the case that both Rtr Pris are equal, the one with the higher router ID is elected.
Once the designated router is elected, it becomes the endpoint for many adjacencies. On a broadcast network this optimizes the flooding procedure by allowing the designated route to multicast its Link State Update packets to the address ALLSPFRouters rather than sending separate packets over each adjacency.
To set the OSPF parameters for the router's network interfaces, use the set interface command.
When responding to the prompts, supply the interface's IP address for each interface in the router and answer the questions that follow. For the parameters listed below you must enter the same value for all routers attached to a common network segment.
The first prompt asks for the OSPF area to which the interface attaches. In the following example, suppose that the interface address mask is 255.255.255.0, indicating that the interface attaches to a subnet (128.185.138.0) of network 128.185.0.0. All other OSPF routers attached to subnet 128.185.138.0 must also have their hello interval set to 10, dead router interval set to 40, and their interface authentication key set to xyz_q.
OSPF Config> set interface
Attaches to area [0.0.0.0]? 0.0.0.1
Interface IP address [0.0.0.0]? 128.185.138.19
Retransmission Interval (in seconds) [5]?
Transmission Delay (in seconds) [1]? 1
Router Priority [1]? 1
Hello Interval (in seconds) [10]? 10
Dead Router Interval (in seconds) [60]? 40
Type Of Service 0 cost [1]? 5
Authentication Key []? xyz_q
Retype Auth. Key []? xyz_q
Enabling Multicast Forwarding
To enable the routing of IP multicast (class D) datagrams, use the enable multicast command. The software prompts you as to whether you want the router to forward multicasts between OSPF areas, as well as whether you want the router to forward multicasts between Autonomous Systems.
Multicasting is a LAN technique that allows copies of a single packet to pass to a selected subset of all possible destinations. Some hardware, for example Ethernet, supports multicast by allowing a network interface to belong to one or more multicast groups.
The IP protocol supports IP multicast routing through IP multicast extensions to OSPF (MOSPF). IP multicast is an extension of LAN multicasting to a TCP/IP Internet. This process lets an IP host send a single datagram (called an IP multicast datagram) that is delivered to multiple destinations. IP multicast datagrams are packets whose destinations are Class D IP addresses. Each Class D address defines a multicast group.
The Internet Group Management Protocol (IGMP) is the OSPF extension that lets an IP host participate in IP multicasting. IGMP lets routers keep track of IP group membership on its local LANs by sending IGMP Host Membership Queries and receiving IGMP Host Membership Reports.
An MOSPF router then distributes group location information throughout the routing domain by flooding a new type (type 6) of link state advertisement, the group-membership-LSA. This enables the MOSPF routers to efficiently forward a multicast datagram to its multiple destinations. This is done by each router calculating the path of the multicast datagram as a tree whose root is the datagram source and whose terminal branches are LANs containing group members.
While running MOSPF, multicast datagram forwarding works in the following ways:
Entering enable multicast, enables multicast with default parameters on all OSPF interfaces. You can change the parameters using the OSPF set interface command.
OSPF Config>enable multicast
Inter-area multicasting enabled(Yes or No): yes
Inter-AS multicasting enabled(Yes or No): yes
By default the router does not forward IP multicast (class D) datagrams. To display the multicast parameters, use the list interfaces command. If multicast is disabled, the multicast parameters are not displayed.
Setting Non-Broadcast Network Parameters
If the router is connected to a non-broadcast, multi-access network, such as an X.25 PDN, you have to configure the parameters below to help the router discover its OSPF neighbors. This configuration is only necessary if the router is eligible to become designated router of the non-broadcast network.
First configure the OSPF poll interval with the following command:
OSPF Config> set non-broadcast
Interface IP address [0.0.0.0]? 128.185.138.19
Poll Interval [120]?
Then configure the IP addresses of all other OSPF routers that will be attached to the non-broadcast network. For each router configured, you must also specify its eligibility to become the designated router.
OSPF Config> add neighbor
Interface IP address [0.0.0.0]? 128.185.138.19
IP Address of Neighbor [0.0.0.0]? 128.185.138.21
Can that router become Designated Router [Yes]?
Enabling AS Boundary Routing
To import routes learned from other protocols (EGP, RIP, and statically configured information) into the OSPF domain, enable AS boundary routing. You must do this even if the only route you want to import is the default route (destination 0.0.0.0).
When enabling AS boundary routing, you are asked which external routes you want to import. You can choose to import, or not to import, routes belonging to several categories. The categories are as follows:
For example, you can choose to import EGP and direct routes, but not RIP or static routes. When you choose to import EGP routes, only the routes that appear in the EGP input exchange tables are actually imported. All routes are imported with cost equal to their routing table cost. They are all imported as either type 1 or type 2 external routes, depending on the routing protocol comparison (See next section).
Independently of the above external categories, you can also configure whether or not to import subnet routes into the OSPF domain. This configuration item defaults to OFF (subnets not imported).
The metric type used in importing routes determines how the imported cost is viewed by the OSPF domain. When comparing two type 2 metrics, only the external cost is considered in picking the best route. When comparing two type 1 metrics, the external and internal costs of the route are combined before making the comparison.
You are asked whether or not you want to originate an OSPF default route. You can answer always, never, or only if you have EGP routes. If originating a default route when EGP routes are available, you can also choose to originate the default only if EGP routes are received from a particular Autonomous System or if a particular route is received through the EGP.
Combinations of these options are possible. For example, you can set the router so that its default is originated only if a route to 10.0.0.0 is received from AS number 12. Setting the AS number to 0 means "from any AS." Setting the network number to 0.0.0.0 means "any routes received."
Use the enable as boundary command as follows:
OSPF Config>enable as boundary
Import EGP routes(Yes or No): yes
Import RIP routes(Yes or No): no
Import static routes(Yes or No): no
Import direct routes(Yes or No): yes
Import subnet routes(Yes or No): no
Originate default if EGP routes available []? yes
From AS number [0]? 12
To network number [0.0.0.0]? 10.0.0.0
Originate as type 1 or 2 [2]?
Default route cost [1]?
Other Configuration Tasks
Setting OSPF Router IDs
Every router in an OSPF routing domain must have a 32-bit router ID. By default, the OSPF router ID is the address of the first OSPF interface appearing in the router's configuration.
You can also explicitly set the OSPF router ID using the IP set router id command. The router ID must still be one of the router's IP interface addresses.
Setting Virtual Links
To maintain backbone connectivity, you must have all of your backbone routers interconnected either by permanent or virtual links. You can configure virtual links between any two area border routers that share a common non-backbone and non-stub area. Virtual links are considered separate router interfaces connecting to the backbone area. Therefore, you are asked to also specify many of the interface parameters when configuring a virtual link.
The example below illustrates the configuration of a virtual link. You must configure virtual links in each of the link's two endpoints. Note that OSPF router IDs are entered in the same form as IP addresses.
OSPF Config> set virtual
Virtual endpt. (Router ID) [0.0.0.0]? 128.185.138.21
Link's transit area [0.0.0.1]? 0.0.0.1
Retransmission Interval (in seconds) [10]?
Transmission Delay (in seconds) [5]?
Hello Interval (in seconds) [30]?
Dead Router Interval (in seconds) [180]?
Authentication Key []? 3-14159
Configuring for Routing Protocol Comparisons
If you use a routing protocol in addition to OSPF, or when you change your routing protocol to OSPF, you must set the Routing Protocol Comparison.
OSPF routing in an AS occurs on the following three levels: Intra-area, Inter-area, and exterior.
Intra-area routing occurs when a packet's source and destination address reside in the same area. For example, N1 and N2 in Area 1 of. Information that is about other areas does not affect this type of routing.
Inter-area routing occurs when the packet's source and destination addresses reside in different areas of an AS, for example, N1 of Area 1 and N7 of Area 2. OSPF does inter-area routing by dividing the path into three contiguous pieces: an intra-area path from source to an area border router; a backbone path between the source and destination areas; and then another intra-area path to the destination. You can visualize this high-level of routing as a star topology with the backbone as hub and each of the areas as a spoke.
Exterior routes are paths to networks that lie outside the AS. These routes originate either from routing protocols, such as Exterior Gateway Protocol (EGP), or from static routes. The exterior routing information that EGP provides does not interfere with the internal routing information that OSPF provides.
AS boundary routers may import exterior routes into the OSPF routing domain. OSPF represents these routes as AS external link advertisements.
OSPF imports external routes in separate levels. The first level, called type 1 routes, is used when the external metric is comparable to the OSPF metric (e.g., they might both use delay in milliseconds). The second level, called external type 2 routes, assumes that the external cost is greater than the cost of any internal OSPF (link-state) path.
Imported external routes are tagged with 32-bits of information. In a router, this 32-bit field indicates the AS number from where the route was received. This enables more intelligent EGP behavior when determining whether to re-advertise the external information to other ASs.
OSPF has a 4-level routing hierarchy as shown below. The set comparison command tells the router where the EGP/RIP/static routes fit in the OSPF hierarchy. The two lower levels consist of the OSPF internal routes. OSPF intra-area and inter-area routes take precedence over information obtained from any other sources, all of which are located on a single level.
Figure 2 OSPF Routing Hierarchy
To put the EGP/RIP/static routes on the same level as OSPF external type 1 routes, set the comparison to 1. To put the EGP/RIP/static routes on the same level as OSPF external type 2 routes, set the comparison to 2. The default is 2.
For example, if the comparison is set to 2, when RIP routes are imported into the OSPF domain, they are imported as type 2 externals. All OSPF external type 1 routes override received RIP routes, regardless of metric. However, if the RIP routes have a smaller cost, the RIP routes override OSPF external type 2 routes. The comparison values for all of your OSPF routers must match. If the comparison values set for the routers are inconsistent, your routing will not function properly.
OSPF Commands
Table 1 lists the OSPF commands.
Press Space twice after you type a command to display the available options for each command. Enter help for information about using the command line interface.
[C] means the command is available at the OSPF config> prompt.
[M] means the command is available at the OSPF> prompt.
Add [C]
Adds ranges to OSPF areas as well as neighbors to non-broadcast networks.
Syntax: add
- range
- neighbor
range area# IP-address IP-address-mask
Adds ranges to OSPF areas. OSPF areas are defined in terms of address ranges. External to the area, a single route is advertised for each address range. For example, if an OSPF area consists of all subnets of the class B network 128.185.0.0, you define it as consisting of a single address range. You would specify the address range as an address of 128.185.0.0 together with a mask of 255.255.0.0. Outside of the area, the entire subnetted network is advertised as a single route to network 128.185.0.0.
Example: add range
Area number [0.0.0.0]? 0.0.0.2
IP Address [0.0.0.0]? 128.185.0.0
IP Address Mask [0.0.0.0]? 255.255.0.0
Inhibit advertisement? [No]:
neighbor
Adds neighbors to non-broadcast networks. If the router is connected to a non-broadcast, multi-access network, such as an X.25 PDN, you have to use this command to help the router discover its OSPF neighbors. This configuration is only necessary if the router is eligible to become designated router of the non-broadcast network. Configure the IP addresses of all other OSPF routers that will be attached to the non-broadcast network. For each router configured, you must also specify its eligibility to become designated router.
Example: add neighbor
Interface IP address [0.0.0.0]? 128.185.138.19
IP Address of Neighbor [0.0.0.0]? 128.185.138.21
Can that router become Designated Router [Yes]?
Advertisement Expansion [M]
Displays the contents of a link state advertisement contained in the OSPF database. For a summary of the router's advertisements use the database command.
A link state advertisement is defined by its link state type, link state ID and its advertising router. There is a separate link state database for each OSPF area. Providing an area-id on the command line tells the software which database you want to search.Note:
Link State IDs, advertising routers (specified by their router IDs), and area IDs take the same format as IP addresses. For example, you can enter the backbone area as 0.0.0.0.
The different kinds of advertisements, which depend on the value given for link-state-type, are
The example below shows an expansion of a router links advertisement. The router's ID is 128.185.184.11. It is an AS boundary router and has three interfaces to the backbone area (all of cost 1). Multicast routing is enabled. Detailed field descriptions are provided with the example shown below.
When displaying router-LSAs and network-LSAs, the reverse cost of each router-to-router link and router-to-transit-network link is displayed, as well as the previously displayed forward cost. This is done because routing of multicast datagrams whose source lies in different areas/ASs is based on reverse cost instead of forward cost. In cases where there is no reverse link (which means that the Dijkstra will never use the link), the reverse cost is shown as "1-way."
The "LS destination" of each group-membership-LSA is a group address. A router originates a group-membership-LSA for each group with members on one or more of the router's attached networks. The group-membership-LSA for the group lists the attached transit networks having type "2" vertices and when there are members belonging to one or more attached stub networks, or if the router itself is a member of the multicast group, a type "1" vertex.
Syntax: advertisement
- ls-type link-state-id advertising router area id
Example: advertisement
Link state type [1]?
Link state ID (destination) [0.0.0.0]? 10.1.2.7
For which area [0.0.0.0]? 2.2.2.2
LS age: 437
LS options: E,MC
LS type: 1
LS destination (ID): 10.1.2.7
LS originator: 10.1.2.7
LS sequence no: 0x80000025
LS checksum: 0xB13C
LS length: 72
Router type:
# router ifcs: 4
Link ID: 10.1.50.16
Link Data: 10.1.2.7
Interface type: 1
No. of metrics: 0
TOS 0 metric: 1 (1)
Link ID: 10.1.22.0
Link Data: 255.255.255.0
Interface type: 3
No. of metrics: 0
TOS 0 metric: 1
Link ID: 10.1.2.16
Link Data: 255.255.255.255
Interface type: 3
No. of metrics: 0
TOS 0 metric: 1
Link ID: 10.1.50.7
Link Data: 255.255.255.255
Interface type: 3
No. of metrics: 0
TOS 0 metric: 0
|
LS age
|
Age of the advertisement in seconds. |
|
LS options
|
Optional OSPF capabilities supported by the piece of the routing domain described by the advertisement. These capabilities are denoted by E (processes type 5 externals; when this is not set to the area to which the advertisement belongs has been configured as a stub), T (can route based on TOS) and MC (can forward IP multicast datagrams). |
|
LS type
|
Classifies the advertisement and dictates its contents: 1 (router links advertisement), 2 (network link advertisement), 3 (summary link advertisement), 4 (summary ASBR advertisement), 5 (AS external link) and 6 (group-membership advertisement). |
|
LS destination
|
Identifies what is being described by the advertisement. Depends on the advertisement type. For router links and ASBR summaries, it is the OSPF router ID. For network links, it is the IP address of the network's designated router. For summary links and AS external links, it is a network/subnet number. For group-membership advertisements, it is a particular multicast group. |
|
LS originator
|
OSPF router ID of the originating router. |
|
LS sequence number
|
Used to distinguish separate instances of the same advertisement. Should be looked at as a signed 32-bit integer. Starts at 0x80000001, and increments by one each time the advertisement is updated. |
|
LS checksum
|
A checksum of advertisement contents, used to detect data corruption. |
|
LS length
|
The size of the advertisement in bytes. |
|
Router type
|
Level of functionality of the router. ASBR means that the router is an AS boundary router, ABR that the router is an area border router, and W that the router is a wildcard multicast receiver. |
|
# Router ifcs
|
The router interface that the advertisement describes. |
|
Link ID
|
Indicates what the interface connects to. Depends on Interface type. For interfaces to routers (point-to-point links), the Link ID is the neighbor's router ID. For interfaces to transit networks, it is the IP address of the network. Designated router. For interfaces to stub networks, it is the network's network/subnet number. |
|
Link Data
|
4 bytes of extra information concerning the link, it is either the IP address of the interface (for interfaces to point-to-point networks and transit networks), or the subnet mask (for interfaces to stub networks). |
|
Interface type
|
One of the following: 1 (point-to-point connection to another router, 2 (connection to transit network, 3 (connection to stub network) or 4 (virtual link). |
|
No. of metrics
|
The number of non-zero TOS values for which metrics are provided for this interface. |
|
TOS 0 metric
|
The cost of the interface. In parenthesis the reverse cost of the link is given (derived from another advertisement). If there is no reverse link, "1-way" is displayed. |
The LS age, LS options, LS type, LS destination, LS originator, LS sequence no, LS checksum and LS length fields are common to all advertisements. The Router type and # router ifcs are seen only in router links advertisements. Each link in the router advertisement is described by the Link ID, Link Data, and Interface type fields. Each link can also be assigned a separate cost for each IP Type of Service (TOS); this is described by the No. of metrics and TOS 0 metric fields (the router currently does not router based on TOS, and looks at the TOS 0 cost only).
The next example shows an expansion of a group-membership advertisement. A group-membership advertisement for a given group/advertising router combination lists those networks directly attached to the advertising router which have group members. It also lists whether the router itself is a member of the specified group. The example below shows that network 128.185.184.0 has members of group 224.0.1.1.
Example: adv 6 224.0.1.1 128.185.184.114
For which area [0.0.0.0]?
LS age: 168
LS options: E
LS type: 6
LS destination (ID): 224.0.1.1
LS originator: 128.185.184.114
LS sequence no: 0x80000001
LS checksum: 0x7A3
LS length: 28
Vertex type: 2
Vertex ID: 128.185.184.114
Area Summary [M]
Displays the statistics and parameters for all OSPF areas attached to the router.
In the example below, the router attaches to a single area (the backbone area) and uses a simple password scheme for the area's authentication. The router has three interfaces attaching to the area, and has found 4 transit networks, 7 routers and no area border routers when calculating the SPF tree for the backbone.
Syntax: area summary
Example: area summary
Area ID Authentication #ifcs #nets #rtrs #brdrs
2.2.2.2 None 1 2 5 3
0.0.0.0 None 1 0 2 2
5.5.5.5 None 1 1 3 1
AS-external Advertisements [M]
Lists the AS external advertisements that belong to the OSPF routing domain. Each advertisement is defined by the following parameters: its link state type (always 5 for AS external advertisements), its link state ID (called the LS destination), and the advertising router (called the LS originator).
Syntax: as-external advertisements
Example: as-external advertisements
Type LS destination LS originator Seqno Age Xsum
5 0.0.0.0 128.185.123.22 0x80000084 430 0x41C7
5 128.185.131.0 128.185.123.22 0x80000080 450 0x71DC
5 128.185.132.0 128.185.123.22 0x80000080 450 0x66E6
5 128.185.144.0 128.185.123.22 0x80000002 329 0xF2CA
5 128.185.178.0 128.185.123.22 0x80000081 450 0x72AA
5 128.185.178.0 128.185.129.40 0x80000080 382 0xDD28
5 129.9.0.0 128.185.123.22 0x80000082 451 0x4F30
5 129.9.0.0 128.185.126.24 0x80000080 676 0x324A
5 134.216.0.0 128.185.123.22 0x80000082 451 0x505A
5 134.216.0.0 128.185.126.24 0x80000080 676 0x3374
5 192.9.3.0 128.185.123.22 0x80000082 451 0xF745
5 192.9.3.0 128.185.126.24 0x80000080 677 0xDA5F
5 192.9.12.0 128.185.123.22 0x80000082 452 0x949F
5 192.9.12.0 128.185.128.41 0x80000080 679 0x31B2
5 192.26.100.0 128.185.123.22 0x80000081 452 0xFDCD
5 192.26.100.0 128.185.126.24 0x80000080 21 0xDEE8
etc.
# advertisements: 133
Checksum total: 0x43CC41
The end of the display shows the total number of AS external advertisements, along with a checksum total over all of their contents. The checksum total is simply the 32-bit sum (carries discarded) of the individual advertisement's LS checksum fields. You can use this information to quickly determine whether two OSPF routers have synchronized databases.
Database Summary [M]
Displays the contents of a particular OSPF area's link state database. AS external advertisements are omitted from the display. Each advertisement is defined by the following parameters: link state type (called Type), link state ID (called the LS destination) and the advertising router (called the LS originator).
Syntax: database summary area-id
Example: database
For which area [0.0.0.0]? 0.0.0.0
Type LS destination LS originator Seqno Age Xsum
1* 10.1.2.7 10.1.2.7 0x80000025 390 0xB13C
1* 10.1.26.9 10.1.26.9 0x80000016 393 0x987D
1* 10.1.26.41 10.1.26.41 0x80000018 122 0x533D
1* 10.1.40.40 10.1.40.40 0x80000015 192 0x317C
1* 10.1.50.16 10.1.50.16 0x80000031 394 0x7A74
2* 10.1.25.40 10.1.40.40 0x80000006 193 0xCB35
2* 10.1.26.16 10.1.50.16 0x80000007 401 0x9669
3* 10.2.50.9 10.1.26.9 0x80000010 397 0xA430
3* 10.5.0.0 10.1.26.41 0x8000000F 133 0x4E9E
3* 10.5.50.41 10.1.26.9 0x80000006 394 0x5D5D
3* 128.185.214.0 10.1.40.40 0x8000000E 740 0x3CA2
6 224.185.0.0 10.1.50.16 0x8000000F 469 0x9B7A
6 225.0.1.36 10.1.2.7 0x80000006 405 0x5CC8
6 225.0.1.36 10.1.26.9 0x8000000F 404 0x8265
6 225.0.1.36 10.1.26.41 0x8000000F 133 0x3A4
6 225.0.1.36 10.1.40.40 0x8000000E 755 0x1D71
6 225.0.1.100 10.1.50.16 0x80000006 476 0x5E14
# advertisements: 17
Checksum total: 0x73121
The end of the display shows the total number of advertisements in the area databas, along with a checksum total over all of their contents. The checksum total is simply the 32-bit sum (carries discarded) of the individual advertisement's LS checksum fields. You can use this information to quickly determine whether two OSPF routers have synchronized databases.Note:
When comparing multicast-capable to non-multicast routers, the above database checksum (and also # advertisements) does not necessarily match because non-multicast routers do not handle or store group-membership-LSAs.
Delete [C]
Deletes OSPF information from the router's configuration memory.
Syntax: delete
- range
- area
- interface
- neighbor
- non-broadcast
- virtual-link
range area# IP-address
Deletes ranges from OSPF areas.
Example: delete range
Area number [0.0.0.0]? 1.1.1.1
IP Address [0.0.0.0]? 128.185.0.0
IP Address Mask [0.0.0.0]? 255.255.0.0
area area#
Deletes OSPF areas from the current OSPF configuration.
Example: delete area 0.0.0.1
interface interface-IP-address
Deletes an interface from the current OSPF configuration.
Example: delete interface 128.185.138.19
neighbor
Deletes neighbors on non-broadcast networks from the current OSPF configuration.
Example: delete neighbor
Interface IP address [0.0.0.0]? 128.185.138.19
IP Address of Neighbor [0.0.0.0]? 128.185.138.21
non-broadcast interface-IP-address
Deletes non-broadcast network information from the current OSPF configuration.
Example: delete non-broadcast 128.185.133.21
virtual-link
Deletes a virtual link. You can configure virtual links between any two backbone routers that have an interface to a common non-backbone area. Virtual links maintain backbone connectivity and must be configured at both endpoints.
Example: delete virtual-link
Virtual endpoint (Router ID) [0.0.0.0]?
Link's transit area [0.0.0.1]?
Disable [C]
Disables either the entire OSPF protocol or just the AS boundary routing capability.
Syntax: disable
- as boundary routing
- multicast-forwarding
- OSPF routing protocol
as boundary routing
Disables the AS boundary routing capability. When disabled, the router does not import external information into the OSPF domain.
Example: disable as boundary routing
multicast forwarding
Disables IP multicast routing on all interfaces. When disabled, the router does not forward IP multicast (Class D) datagrams.
Example: disable multicast forwarding
OSPF routing protocol
Disables the entire OSPF protocol.
Example: disable OSPF routing protocol
Dump Routing Tables [M]
Displays the routes that have been calculated by OSPF and are now present in the routing table. Its output is similar to the IP monitoring dump routing tables command.
Syntax: dump
Example: dump
Type Dest net Mask Cost Age Next hop(s)
Sbnt 10.0.0.0 FF000000 1 0 None
Rnge 10.1.0.0 FFFF0000 1 0 None
SPF 10.1.2.7 FFFFFFFF 2 2 10.1.26.16
SPF 10.1.2.16 FFFFFFFF 3 3 10.1.26.16
SPF 10.1.7.16 FFFFFFFF 3 3 10.1.26.16
SPF 10.1.7.40 FFFFFFFF 2 2 10.1.26.16
SPF 10.1.22.0 FFFFFF00 3 3 10.1.26.16
SPF 10.1.25.0 FFFFFF00 2 2 10.1.26.16
SPF* 10.1.26.0 FFFFFF00 1 1 FDDI/0
SPF 10.1.40.40 FFFFFFFF 2 2 10.1.26.16
SPF 10.1.50.7 FFFFFFFF 2 2 10.1.26.16
SPF 10.1.50.16 FFFFFFFF 1 1 10.1.26.16
SPF 10.2.50.9 FFFFFFFF 1 1 10.1.26.9
Rnge 10.5.0.0 FFFF0000 1 0 None
Dir* 10.5.9.0 FFFFFF00 1 0 SL/0
SPF 10.5.9.14 FFFFFFFF 1 1 10.5.9.14
SPF 10.5.9.41 FFFFFFFF 2 2 SL/0
SPF 10.5.22.0 FFFFFF00 8 8 10.5.9.14
SPF 10.5.33.0 FFFFFF00 2 2 10.5.9.14
SPF 10.5.50.14 FFFFFFFF 1 1 10.5.9.14
SPF 10.5.50.41 FFFFFFFF 0 0 SINK/0
Stat* 128.185.0.0 FFFF0000 1 0 10.1.26.16
Routing table size: 768 nets (49152 bytes), 22 nets known
Enable [C]
Enables either the entire OSPF protocol or just the AS boundary routing capability.
Syntax: enable
- as boundary routing
- multicast routing
- OSPF routing protocol
as boundary routing
Enables the AS boundary routing capability that allows you to import routes learned from other protocols (EGP, RIP, and statically configured information) into the OSPF domain.
Example: enable as boundary routing
Import EGP routes(Yes or No): yes
Import RIP routes(Yes or No): no
Import static routes(Yes or No): no
Import direct routes(Yes or No): yes
Import subnet routes(Yes or No): no
Originate default if EGP routes available []? yes
From AS number [0]? 12
To network number [0.0.0.0]? 10.0.0.0
Originate as type 1 or 2 [2]?
Default route cost [1]?
multicast forwarding
Enables the forwarding of IP multicast (Class D) datagrams. When enabling multicast routing, you are also prompted for forwarding IP multicast datagrams between OSPF areas and between Autonomous Systems. To run MOSPF (OSPF with multicast extensions), a router currently running OSPF needs to use only this command. You do not need to re-enter its configuration information.
Example: enable multicast forwarding
Inter-area multicasting enabled (Yes or No): yes
Inter-AS multicasting enabled (Yes or No): yes
OSPF routing protocol
Enables the OSPF routing protocol. When enabling OSPF, you must supply the following values that are used to estimate the size of the OSPF link state database:
Example: enable OSPF routing protocol
Estimated # external routes[0]? 200
Estimated # OSPF routers [0]? 60
Exit [C] [M]
Returns to the previous prompt.
Syntax: exit
IGMP [C] [M]
Displays the IGMP configuration or monitoring prompt. See IGMP Commands for information on the commands available at these prompts.
Syntax: igmp
Example: igmp
Internet Group Management Protocol Configuration
IGMP Config>
Interface Summary [M]
Displays statistics and parameters related to OSPF interfaces. If no arguments are given, it displays a single line summarizing each interface. If you enter an interface's IP address, detailed statistics for that interface are displayed.
Syntax: interface summary interface-ip-address
Example: interface
Ifc Address Phys assoc. Area Type State #nbrs #adjs
10.1.26.41 FDDI/0 2.2.2.2 Brdcst 32 2 2
10.5.9.41 SL/0 5.5.5.5 P-P 8 2 1
- Unnumbered - VL/0 0.0.0.0 VLink 8 1 1
|
Ifc Address
|
Interface IP address. |
|
Assoc Area
|
Attached area ID. |
|
Type
|
Brdcst (broadcast, such as an Ethernet interface),
P-P (a point-to-point network, such as a serial line),
Multi (non-broadcast, multi-access, such as an X.25 connection),
and VLink (an OSPF virtual link). |
|
State
|
Can be one of the following: 1 (down), 2 (looped back), 4 (waiting), 8 (point-to-point), 16 (DR other), 32 (backup DR) or 64 (designated router). |
|
#nbrs
|
Number of neighbors. This is the number of routers whose hellos have been received, plus those that have been configured. |
|
#adjs
|
Number of adjacencies. This is the number of neighbors in state Exchange or greater. These are the neighbors with whom the router has synchronized or is in the process of synchronization. |
Example: interface 128.185.125.22
Interface address: 10.1.26.41
Attached area: 2.2.2.2
Physical interface: FDDI/0
Interface mask: 255.255.255.0
Interface type: Brdcst
State: 32
Designated Router: 10.1.26.16
Backup DR: 10.1.26.41
DR Priority: 1 Hello interval: 10 Rxmt interval: 5
Dead interval: 40 TX delay: 1 Poll interval: 0
Max pkt size: 4352 TOS 0 cost: 1
# Neighbors: 2 # Adjacencies: 2 # Full adjs.: 2
# Mcast floods: 31 # Mcast acks: 98
MC forwarding: on DL unicast: off IGMP monitor: on
# MC data in: 0 # MC data acc: 0 # MC data out: 0
|
Attached Area
|
Attached area ID. |
|
Physical interface
|
Displays physical interface type and number. |
|
Interface Mask
|
Interface subnet mask. |
|
Interface type
|
Can be either Brdcst (broadcast, e.g., an Ethernet interface), P-P (a point-to-point network, e.g., a synchronous serial line), Multi (non-broadcast, multi-access, e.g., an X.25 connection) and VLink (an OSPF virtual link). |
|
State
|
Can be one of the following: 1 (Down), 2 (Attempt), 4 (Init), 8 (2-Way), 16 (ExStart), 32 (Exchange), 64 (Loading) or 128 (Full). |
|
Designated Router
|
IP address of the designated router. |
|
Backup DR
|
IP address of the backup designated router. |
|
DR Priority
|
Priority assigned to designated router. |
|
Hello interval
|
Current hello interval value. |
|
Rxmt interval
|
Current retransmission interval value. |
|
Dead interval
|
Current dead interval value. |
|
TX delay
|
Current transmission delay value. |
|
Poll interval
|
Current poll interval value. |
|
Max pkt size
|
Maximum size for an OSPF packet sent out this interface. |
|
TOS 0 cost
|
Interface's TOS 0 cost. |
|
# Neighbors
|
Routers whose hellos have been received, plus those that have been configured. |
|
# Adjacencies
|
Neighbors in state Exchange or greater. |
|
# Full adj
|
Full adjacencies is the number of neighbors whose state is Full (and therefore, with which the router has synchronized databases). |
|
# Mcast Floods
|
Link state updates flooded out the interface (not counting retransmissions). |
|
# Mcast acks
|
Link state acknowledgements flooded out the interface (not counting retransmissions). |
|
MC forwarding
|
Displays whether multicast forwarding has been enabled for the interface. |
|
DL unicast
|
Displays whether multicast datagrams are to be forwarded as data-link multicasts or as data-link unicasts. |
|
IGMP monitor
|
Displays whether IGMP is enabled on the interface. |
|
# MC data in
|
Multicast datagrams received on this interface and then successfully forwarded. |
|
# MC data acc
|
Multicast datagrams successfully forwarded. |
|
# MC data out
|
Datagrams sent out the interface (either as data-link multicasts or data-link unicasts). |
List [C]
Displays OSPF configuration information.
Syntax: list
- all
- areas
- interfaces
- non-broadcast
- virtual-link
all
Lists all OSPF related configuration information.
Example: list all
--Global configuration--
OSPF Protocol: Enabled
# AS ext. routes: 5000
Estimated # routers: 50
External comparison: Type 2
AS boundary capability: Disabled
Multicast forwarding: Enabled
Inter-area multicast: Enabled
Inter-AS multicast: Disabled
--Area configuration--
Area ID AuType Stub? Default-cost Import-summaries?
2.2.2.2 0=None No N/A N/A
0.0.0.0 0=None No N/A N/A
5.5.5.5 0=None Yes 0 Yes
--Area ranges--
Area ID Address Mask Advertise?
2.2.2.2 10.1.0.0 255.255.0.0 Yes
5.5.5.5 10.5.0.0 255.255.0.0 Yes
--Interface configuration--
IP address Area Cost Rtrns TrnsDly Pri Hello Dead
10.1.26.41 2.2.2.2 1 5 1 1 10 40
10.5.9.41 5.5.5.5 1 5 1 1 10 40
Multicast parameters
IP address MCForward DLUnicast
10.1.26.41 On Off
10.5.9.41 On Off
--Virtual link configuration--
Virtual endpoint Transit area Rtrns TrnsDly Hello Dead
10.1.26.9 2.2.2.2 10 5 30 180
--NBMA configuration--
Interface Addr Poll Interval
10.5.9.41 120
--Neighbor configuration--
Neighbor Addr Interface Address DR eligible?
10.5.9.14 10.5.9.41 yes
areas
Lists all information concerning configured OSPF areas.
Example: list areas
--Area configuration--
Area ID AuType Stub? Default-cost Import-summaries?
2.2.2.2 0=None No N/A N/A
0.0.0.0 0=None No N/A N/A
5.5.5.5 0=None Yes 0 Yes
--Area ranges--
Area ID Address Mask Advertise?
2.2.2.2 10.1.0.0 255.255.0.0 Yes
5.5.5.5 10.5.0.0 255.255.0.0 Yes
interfaces
For each interface its IP address is printed, together with configured parameters.
Example: list interfaces
--Interface configuration--
IP address Area Cost Rtrns TrnsDly Pri Hello Dead
10.1.26.41 2.2.2.2 1 5 1 1 10 40
10.5.9.41 5.5.5.5 1 5 1 1 10 40
Multicast parameters
IP address MCForward DLUnicast
10.1.26.41 On Off
10.5.9.41 On Off
- Note:
Multicast parameters are not displayed if the multicast is disabled.
non-broadcast
Lists all information related to interfaces connected to non-broadcast networks. For each non-broadcast interface, as long as the router is eligible to become designated router on the attached network, the polling interval is displayed together with a list of the router's neighbors on the non-broadcast network.
Example: list non-broadcast
Interface Addr Poll Interval
128.185.235.34 120
virtual-link
Lists all virtual links that have been configured with this router as endpoint. "Virtual endpoint" indicates the OSPF router ID of the other endpoint. "Transit area" indicates the non-backbone area through which the virtual link is configured. OSPF treats virtual links similarly to point-to-point networks. The other parameters listed (Rtrns, TrnsDly, Hello, and Dead) are maintained for all interfaces. See the OSPF list interfaces command for more information.
Example: list virtual-link
--Virtual link configuration--
Virtual endpoint Transit area Rtrns TrnsDly Hello Dead
10.1.26.9 2.2.2.2 10 5 30 180
Mcache [M]
Displays a list of currently active multicast cache entries. Multicast cache entries are built on demand, whenever the first matching multicast datagram is received. There is a separate cache entry (and therefore a separate route) for each datagram source network and destination group combination.
Cache entries are cleared on topology changes (e.g., a point-to-point line in the MOSPF system going up or down), and on group membership changes.
Syntax: mcache
Example: mcache
0: FDDI/0 1: SL/0 2: SL/1
3: SL/2 4: SL/3 5: Eth/0
6: Eth/1 7: Eth/2 8: Eth/3
9: Eth/4 10: Eth/5 11: Eth/6
12: Eth/7 13: Internal
Source Destination Count Upst Downstream
10.5.50.41 225.0.1.100 3 Local 0
10.5.50.14 225.0.1.100 3 1 0
10.2.50.9 225.0.1.100 3 0 None
10.1.50.7 225.0.1.100 3 0 None
10.1.50.16 225.0.1.36 3 0 1,13
There is more information in a multicast forwarding cache entry. You can display a cache entry in detail by providing the source and destination of a matching datagram on the command line. If a matching cache entry is not found, one is built. A sample of this command follows:
Example: mcache 128.185.182.9 224.0.1.2
source Net: 128.185.182.0
Destination: 224.0.1.2
Use Count: 472
Upstream Type: Transit Net
Upstream ID: 128.185.184.114
Downstream: 128.185.177.11 (TTL = 2)
In addition to the information shown in the short form of the mcache command, the following fields are displayed:
Mstats [M]
Displays various multicast routing statistics. The command indicates whether multicast routing is enabled and whether the router is an inter-area and/or inter-AS multicast forwarder.
Syntax: mstats
Example: mstats
MOSPF forwarding: Enabled
Inter-area forwarding: Enabled
DVMRP forwarding: Disabled
Datagrams received: 4301 Datagrams (ext source): 0
Datagrams fwd (multicast): 4122 Datagrams fwd (unicast): 0
Locally delivered: 2009 No matching rcv interface: 0
Unreachable source: 0 Unallocated cache entries: 0
Off multicast tree: 0 Unexpected DL multicast: 0
Buffer alloc failure: 0 TTL scoping: 0
# DVMRP routing entries: 0 # DVMRP entries freed: 0
# fwd cache alloc: 57 # fwd cache freed: 52
# fwd cache GC: 0 # local group DB alloc: 1
# local group DB free: 0
The number of cache hits can be calculated as the number of datagrams received (Datagrams received) minus the total of datagrams discarded due to No matching rcv interface, Unreachable source and Unallocated cache entries, and minus # local group DB alloc." The number of cache misses is simply # local group DB alloc.
Neighbor Summary [M]
Displays statistics and parameters related to OSPF neighbors. If no arguments are given, a single line is printed summarizing each neighbor. If an neighbor's IP address is given, detailed statistics for that neighbor are displayed.
Syntax: neighbor summary neighbor-ip-address
Example: neighbor
Neighbor addr Neighbor ID State LSrxl DBsum LSreq Ifc
128.185.125.39 128.185.136.39 128 0 0 0 Pro/1
128.185.125.41 128.185.128.41 8 0 0 0 Pro/1
128.185.125.38 128.185.125.38 8 0 0 0 Pro/1
128.185.125.25 128.185.129.25 8 0 0 0 Pro/1
128.185.125.40 128.185.129.40 128 0 0 0 Pro/1
128.185.125.24 128.185.126.24 8 0 0 0 Pro/1
Example: neighbor 128.185.138.39
The meaning of most of the displayed fields is given in section 10 of the OSPF specification (RFC 1131).
Neighbor IP address: 128.185.184.34
OSPF Router ID: 128.185.207.34
Neighbor State: 128
Physical interface: Eth/1
DR choice: 128.185.184.34
Backup choice: 128.185.184.11
DR Priority: 1
Nbr options: E,MC
DB summ qlen: 0 LS rxmt qlen: 0 LS req qlen: 0
Last hello: 7
# LS rxmits: 108 # Direct acks: 13 # Dup LS rcvd: 572
# Old LS rcvd: 2 # Dup acks rcv: 111 # Nbr losses: 29
# Adj. resets: 30
|
Neighbor IP addr
|
Neighbor IP address. |
|
OSPF router ID
|
Neighbor's OSPF router ID. |
|
Neighbor State
|
Can be one of the following: 1 (Down), 2 (Attempt), 4 (Init), 8 (2-Way), 16 (ExStart), 32 (Exchange), 64 (Loading) or 128 (Full). |
|
Physical interface
|
Physical interface type and number of the router and neighbor's common network. |
|
DR choice, backup choice, DR priority
|
Values seen in the the last hello received from the neighbor. |
|
Nbr options
|
Optional OSPF capabilities supported by the neighbor. These capabilities are E (processes type 5 externals; when this is not set the area to which the common network belongs has been configured as a stub), T (can route based on TOS) and MC (can forward IP multicast datagrams). This field is valid only for those neighbors in state Exchng or greater. |
|
DBsumm qlen
|
Advertisements waiting to be summarized in Database Description packets. It should be zero except when the neighbor is in state Exchange. |
|
LS rxmt qlen
|
Advertisements that have been flooded to the neighbor, but not yet acknowledged. |
|
LS req qlen
|
Advertisements that are being requested from the neighbor in state Loading. |
|
Last hello
|
Seconds since a hello was received from the neighbor. |
|
# LS rxmits
|
Retransmissions that occurred during flooding. |
|
# direct acks
|
Responses to duplicate link state advertisements. |
|
# Dup LS rcvd
|
Duplicate retransmissions that occurred during flooding. |
|
# Old LS rcvd
|
Old advertisements received during flooding. |
|
# Dup acks rcvd
|
Duplicate acknowledgements received. |
|
# Nbr losses
|
Number of times the neighbor has transitioned to Down state. |
|
# Adj. resets
|
Counts entries to state ExStart. |
Ping Address [M]
Ping uses the ICMP protocol's ECHO_REQUEST datagram to elicit an ICMP ECHO_RESPONSE from the specified host or network gateway. Ping is generally used to test for reachability between network nodes.
Syntax: ping address
Example: ping 10.1.155.29
-----------10.1.151.29 PING Statistics-------------
7 packets transmitted, 7 packets received, 0% packet loss
Routers [M]
Displays routes that OSPF has calculated and are now present in the routing table. - Note:
The routers command shows only border routers, used to calculate inter-area routes, and boundary routers, used to calculate external routes.
Syntax: routers
Example: routers
DType RType Destination Mask Cost Next hop(s)
ASBR SPF 128.185.142.9 FFFFFFFF 1 128.185.142.9
Fadd SPF 128.185.142.98 FFFFFFFF 1 0.0.0.0
Fadd SPF 128.185.142.7 FFFFFFFF 1 0.0.0.0
Fadd SPF 128.185.142.48 FFFFFFFF 1 0.0.0.0
Fadd SPF 128.185.142.111 FFFFFFFF 1 0.0.0.0
Fadd SPF 128.185.142.38 FFFFFFFF 1 0.0.0.0
Fadd SPF 128.185.142.11 FFFFFFFF 1 0.0.0.0
BR SPF 128.185.142.9 FFFFFFFF 1 128.185.142.9
BR SPF 128.185.142.9 FFFFFFFF 2 128.185.184.114
Fadd SPF 128.185.142.47 FFFFFFFF 1 0.0.0.0
Set [C]
Changes the configuration information of OSPF areas, interfaces, non-broadcast networks, or virtual links. This command also allows you to set the way in which OSPF routes are compared to information obtained from other routing protocols.
Syntax: set
- area
- comparison
- interface
- non-broadcast
- virtual-link
area
Sets the parameters for an OSPF area. If no areas are defined, the router software assumes that all the router's directly attached networks belong to the backbone area (area ID 0.0.0.0).
Example: set area
Area number [0.0.0.0]? 0.0.0.1
Authentication type [1]? 1
Is this a stub area? (Yes or No): no
comparison
Tells the router where the EGP/RIP/static routes fit in the OSPF hierarchy. The two lower levels consist of the OSPF internal routes. OSPF internal routes take precedence over information gained from any other sources, all of which are located on a single level.
Example: set comparison
Compare to type 1 or 2 externals [2]?
interface
Sets the OSPF parameters for the router's network interfaces.
Example: set interface
Attaches to area [0.0.0.0]? 0.0.0.1
Interface IP address [0.0.0.0]? 128.185.138.19
Retransmission Interval (in seconds) [5]?
Transmission Delay (in seconds) [1]? 1
Router Priority [1]? 1
Hello Interval (in seconds) [10]? 10
Dead Router Interval (in seconds) [60]? 40
Type Of Service 0 cost [1]? 5
Authentication Key []? xyz_q
Retype Auth. Key []? xyz_q
Forward multicast datagrams (Yes or No)? Yes
Forward as data-link unicasts (Yes or No)? No
When responding to the prompts, supply the IP address for each interface in the router and answer the questions that follow. For the parameters listed below you must enter the same value for all routers attached to a common network.
The first prompt asks for the OSPF area to which the interface attaches. For example, suppose that the interface address mask is 255.255.255.0, indicating that the interface attaches to a subnet (128.185.138.0) of network 128.185.0.0. All other OSPF routers attached to subnet 128.185.138.0 must also have their hello interval set to 10, dead router interval set to 40, and their interface authentication key set to xyz_q.
If you have enabled multicast routing, the MOSPF parameters for each OSPF interface are set to their default values. This means the following:
To change the MOSPF parameters, use the set interface command. You will be queried for multicast parameters (the last two parameters shown in the output display above) only if you have first enabled multicast forwarding.
On networks that lie on the edge of an Autonomous System, where multiple multicast routing protocols (or multiple instances of a single multicast routing protocol) may exist, you may need to configure forwarding as data-link unicasts to avoid unwanted datagram replication. In any case, for all routers attached to a common network, the interface parameters forward multicast datagrams and forward as data-link unicasts should be configured identically.
non-broadcast
Helps the router discover its OSPF neighbors. This configuration is only necessary if the router is eligible to become designated router of the non-broadcast network. After using this command, you must configure the IP addresses of all other OSPF routers that will be attached to the non-broadcast network. See the add neighbor command for more information.
Example: set non-broadcast
Interface IP address [0.0.0.0]? 128.185.138.19
Poll Interval [120]?
virtual-link
Configures virtual links between any two area border routers. To maintain backbone connectivity you must have all of your backbone routers interconnected either by permanent or virtual links. Virtual links are considered to be separate router interfaces connecting to the backbone area. Therefore, you are asked to also specify many of the interface parameters when configuring a virtual link.
Example: set virtual-link
Virtual endpt. (Router ID) [0.0.0.0]? 128.185.138.21
Link's transit area [0.0.0.1]? 0.0.0.1
Retransmission Interval (in seconds) [10]?
Transmission Delay (in seconds) [5]?
Hello Interval (in seconds) [30]?
Dead Router Interval (in seconds) [180]?
Authentication Key []? 3-14159
Size [M]
Displays the number of LSAs currently in the link state database, categorized by type.
Syntax: size
Example: size
# Router-LSAs: 7
# Network-LSAs: 6
# Summary-LSAs: 14
# Summary Router-LSAs: 2
# AS External-LSAs: 44
# Group-membership-LSAs: 21
Statistics [M]
Displays statistics generated by OSPF. The statistics indicate how well the implementation is performing, including its memory and network utilization. Many of the fields displayed are confirmation of the OSPF configuration.
Syntax: statistics
Example: statistics
S/W version: 2.1
OSPF Router ID: 10.1.26.41
External comparison: Type 2
AS boundary capability: No
Import external routes: None
Orig. default route: No (0,0.0.0.0)
Default route cost: (1, Type 2)
Default forward. addr: 0.0.0.0
Attached areas: 3 Estimated # external routes: 5000
Estimated # OSPF routers: 50 Estimated heap usage: 464800
OSPF packets rcvd: 3682 OSPF packets rcvd w/ errs: 0
Transit nodes allocated: 192 Transit nodes freed: 177
LS adv. allocated: 460 LS adv. freed: 431
Queue headers alloc: 32 Queue headers avail: 32
# Dijkstra runs: 86 Incremental summ. updates: 1
Incremental VL updates: 21 Buffer alloc failures: 0
Multicast pkts sent: 2465 Unicast pkts sent: 33
LS adv. aged out: 0 LS adv. flushed: 86
Incremental ext. updates: 84
External LSA database:
Current state: Normal
Number of LSAs: 0
Number of overflows: 0
Traceroute [M]
Traceroute works similarly to ping, and is used to test for connectivity and isolate faults in the network. Unlike ping, traceroute records and displays the route taken to the host or network gateway.
Syntax: traceroute address
Example: traceroute 10.1.151.29
TRACEROUTE 10.1.151.29: 56 data bytes
1 10.1.151.29 2 ms 0 ms 0 ms
Weight [M]
Changes the cost of one of the router's OSPF interfaces. This new cost is immediately flooded throughout the OSPF routing domain, causing routes to be updated accordingly.
The cost of the interface reverts to its configured cost whenever you restart or reload the router. To make the cost change permanent, reconfigure the appropriate OSPF interface after entering the weight command. This command causes a new router links advertisement to be originated, unless the cost of the interface does not change.
Syntax: weight ip-interface-address new-cost
Example: weight 128.185.124.22 2
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