CCNA 2 Chapter 2: Static Routing

default static route

A default static route is an administratively configured entry in a router's routing table that specifies where traffic for all unknown networks should be sent. A default static route is a route that matches all packets. ▪ A default route identifies the gateway IP address to which the router sends all IP packets that it does not have a learned or static route. ▪ A default static route is simply a static route with 0.0.0.0/0 as the destination IPv4 address.

Reach Remote Networks

A router can learn about remote networks in one of two ways: • Manually - Remote networks are manually entered into the route table using static routes. • Dynamically - Remote routes are automatically learned using a dynamic routing protocol.

Troubleshoot a Missing Route

IOS troubleshooting commands include: ▪ ping ▪ Extended ping enables you to specify the source IP address for the ping packets. ▪ traceroute ▪ show ip route ▪ show ip interface brief ▪ show cdp neighbors detail

ip route command

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 small network. We have two commands to configure the static route. Router(config)# ip route destination_network_# [subnet_mask] IP_address_of_next_hop_neighbor [administrative_distance] [permanent] and Router(config)# ip route destination_network_# [subnet_mask] interface_to_exit [administrative_distance] [permanent]

IPv6 Static Routes Next-Hop Options

Next-hop static IPv6 route - Only the next-hop IPv6 address is specified ▪ Directly connected static IPv6 route - Only the router exit interface is specified ▪ Fully specified static IPv6 route - The next-hop IPv6 address and exit interface are specified

Static Route Applications

Static Routes are often used to: ▪ Connect to a specific network. ▪ Provide a Gateway of Last Resort for a stub network. ▪ Reduce the number of routes advertised by summarizing several contiguous networks as one static route. ▪ Create a backup route in case a primary route link fails.

When to Use Static Routes

Static routing has three primary uses: ▪ Providing ease of routing table maintenance in smaller networks. ▪ Routing to and from stub networks. A stub network is a network accessed by a single route, and the router has no other neighbors. ▪ Using a single default route to represent a path to any network that does not have a more specific match with another route in the routing table.

Why Use Static Routing?

Static routing provides some advantages over dynamic routing, including: ▪ Static routes are not advertised over the network, resulting in better security. ▪ Static routes use less bandwidth than dynamic routing protocols, no CPU cycles are used to calculate and communicate routes. ▪ The path a static route uses to send data is known.

floating static route

static routes that are used to provide a backup path to a primary static or dynamic route

Automatically Installed Host Routes

A host route is an IPv4 address with a 32-bit mask or an IPv6 address with a 128-bit mask. ▪ Automatically installed when an IP address is configured on the router. ▪ The local routes are marked with "L" in the output of the routing table.

summary static route

A single static route that can represent multiple contiguous networks to reduce the number of entries in a routing table.

Configure a Default Static IPv6 Route

Branch(config)#ipv6 route ::/0 Gi0/1 2001:DB8:D1A5:C900::2

Verify IPv6 static routes

In addition to ping and traceroute, commands to verify static routes include: ▪ show ipv6 route ▪ show ipv6 route static ▪ show ipv6 route network

default static route

A default static route is an administratively configured entry in a router's routing table that specifies where traffic for all unknown networks should be sent.

Solve a Connectivity Problem

Finding a missing (or misconfigured) route requires using the right tools in a methodical manner. ▪ Use the ping command to confirm the destination can't be reached. ▪ A traceroute would also reveal the closest router (or hop) that fails to respond as expected. In this case, the router would then send an Internet Control Message Protocol (ICMP) destination unreachable message back to the source. ▪ The next step is to investigate the routing table using the show ip route command. Look for missing or misconfigured routes. ▪ Incorrect static routes are a common cause of routing problems.

Configure IPv6 Default Routes Floating Static Routes

Floating static routes have an administrative distance greater than the administrative distance of another static route or dynamic routes. ▪ The static route "floats" and is not used when the route with the better administrative distance is active. ▪ If the preferred route is lost the floating static route can take over.

Configure an IPv4 Floating Static Route

R1(config)#router rip R1(config-router)#version 2 R1(config-router)#no auto-summary R1(config-router)#network 192.168.12.0

Configure a Default Static Route

Router(config)# ip route 0.0.0.0 0.0.0.0 IP_address_of_next_hop_neighbor [administrative_distance] [permanent] Or Router(config)# ip route 0.0.0.0 0.0.0.0 interface_to_exit [administrative_distance] [permanent]

Verify a Default IPv6 Static Route

Show ip route static

Verify a Default Static Route

Show ip route static

Verify a Static Route

Show ip route | begin gateway Show ip route then IP address

Next-Hop Options

The next hop can be identified by an IP address, exit interface, or both. How the destination is specified creates one of the three following route types: ▪ Next-hop route - Only the next-hop IP address is specified. ▪ Directly connected static route - Only the router exit interface is specified. ▪ Fully specified static route - The next-hop IP address and exit interface are specified.

Test the IPv4 Floating Static Route

To test a floating static route: ▪ Use the show ip route command to verify that the routing table is using the default static route. ▪ Use the traceroute command to follow the traffic flow out the primary route. ▪ Disconnect the link or shutdown the primary interface(s). In the curriculum example the serial interfaces on R2 are shutdown. ▪ Use a show ip route command to verify that the routing table is using the floating static route. ▪ Use a traceroute command to follow the traffic flow out the backup route

Default Static IPv6 Route

a default static route similar to the IPv4 quad zero (0.0.0.0) static default route. Instead, the IPv6 command uses the ::/0 notation to specify all networks. For example, a default static route as specified by the "::/0" entry is configured on router R2 to reach all other networks connected to R1.

Fully Specified Static IPv6 Route

in a fully specified static route, both the output interface and the next hop are specified. This form of static route is used when the output interface is a multi-access one and it is necessary to explicitly identify the next hop. The next hop must be directly attached to the specified output interface. The following example shows a definition of a fully specified static route: ipv6 route 2001:DB8:/32 ethernet1/0 2001:DB8:3000:1 A fully specified route is valid (that is, a candidate for insertion into the IPv6 routing table) when the specified IPv6 interface is IPv6-enabled and up.

Directly Attached Static Routes

ipv6 route 2001:DB8::/32 gigabitethernet1/0/0