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show ip route command explained

Multiarea

How to Verify Multiarea OSPF

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The majority of the command for multiarea OSPF verification is the same as the command we already used in the verification of single area OSPF. The command, “show ip ospf neighbor”, “show ip ospf” and show ip ospf interface are the same command. The following command specifically includes the information of multiarea OSPF.

  • show ip protocols
  • show ip ospf interface brief
  • show ip route ospf
  • show ip ospf database

The command can also be used for OSPFv3, simply substitute ip with ipv6. In this article, we will use the same topology of OSPF, which we have used in the previous article. Figure 1 illustrates the OSPF topology.

Multiarea

Verify General Multiarea OSPF Settings

We can verify the general multiarea OSPF setting using the “show ip protocols” command. The output of the command displays the configured routing protocols on a router including router ID, several areas in the router, and networks included within the routing protocol configuration. Figure 2 illustrates the OSPF settings of R2. Notice that the command shows that there are two areas. The Routing for Networks segment identifies the networks and their particular areas.

We can also use the “show ip ospf interface brief” command to show brief OSPF-related information of OSPF-enabled interfaces. This command provides helpful information, such as the OSPF process ID, the area that the interfaces are in, and the cost of the interface.

Verify the OSPF Routes

The “show ip route” is the most common command to verify a multiarea OSPF configuration. We can add the “ospf” parameter to display only OSPF-related information.

Figure 3 displays the routing table of R2. See the O IA entries in the routing table, which illustrates networks learned from other areas. O specifically represents OSPF routes, and IA represents interarea routes, meaning that the route is originated from another area.

The [110/2], [110/3] entry in the routing table illustrates the administrative distance and cost of the route. The administrative distance is (110) and the total cost of the routes (cost of 2 or 3).

Verify the Multiarea OSPF LSDB

To examine the contents of the LSDB we can use “show ip ospf database” command. Several options are available with this command. Figure 4 illustrates the content of the LSDB of R2.

Notice R2 has database entries for area 0 and area 10, so ABRs must maintain a separate LSDB for each area to which they belong. In the output, Router Link States identifies the number of routes for each area. The Summary Net Link States for identifies networks learned from other areas and which neighbour advertised the network for both areas.

Verify Multiarea OSPFv3

We can verify the OSPFv3 with similar verification commands with only substitute ip with ipv6. We can use all the commands discussed for OSPFv2 verification.

IP Route Command – Complete Explanation

IP Route Command – Complete Explanation

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In this article, I am going to explain the “IP route” command and its parameter, argument, and options in detail. IP route command is used to configure the static route. Static routes are the most secure way of routing. They will also increase overall network performance. These features are extremely helpful in a small network. The syntax of the command is the following:

Router(config)# ip route network-address subnet-mask { ip-address |interface-type interface-number [ ip-address ]} [ distance ] [ name name ] [ permanent ] [ tag tag ]

The description of the parameter using the IP route command is the following:

network-address

This is the first parameter of the ip route command. It specifies the destination network address that is required to add to the routing table.

subnet-mask

The destination network subnet mask is to be added to the routing table. We can also use a summarized subnet mask for a group of networks to cut the routing table overheads and for speedy processing.

ip-address

This parameter provides a way to reach the destination network. It is the IP address of the connecting router to use to forward the packet to the remote destination network. This is also called the next hop of the router.

exit-interface

This command also does the same job just like an ip-address parameter but in different ways. It specifies the exit interface and tells the router that if it receives a packet for the destination specified by the previous parameter then exits that packet from this interface. Device connected on another end of this interface will take care of the packet.

Note:- One or both of ip-address and exit-interface must be used.

distance

Administrative distance is the trustworthiness of the route. The value of the administrative distance is from 0 to 255. The route with the lowest AD value will be chosen while forwarding the packet. By default static route has two AD values depending on the previous parameter.

If a static route uses an exit interface, the administrative distance will be 0. If the static route is configured with the next-hop IP address, the administrative distance value will be 0. Usually, this is used to create a floating static route or multiple routes to the same destination. For example, we can create a primary and backup path for the destination network.

name

we use this parameter to assign a name to the route.

permanent

If we configure the route with parameter permanent, in case a route goes down router will not remove it from the routing table. The parameter permanent will keep this route in the routing table.

It’s an optional parameter we can configure the route without this parameter. This parameter is important for packet security. If you never want packets to take another path.

Tag

By using this parameter we can specify a tag number when configuring a static route. The tag can then be matched with a route map. The route map is an access list that allows you to permit, deny, and change the parameters of routing advertisements.