Chapter 2 - Static Routing

Configure a Directly Connected Static Route

When configuring a static route, another option is to use the exit interface to specify the next-hop address. uses the serial interface ip instead of the next-hop ip

Defualt Static Route are used when:

When no other routes in the routing table match the packet destination IP address. In other words, when a more specific match does not exist. A common use is when connecting a company's edge router to the ISP network. When a router has only one other router to which it is connected. In this situation, the router is known as a stub router. A default route can be dynamically learned or statically configured. A default static route is simply a static route with 0.0.0.0/0 as the destination IPv4 address.

ip route 192.168.10.0 255.255.255.0 10.10.10.2 5Which route would have to go down in order for this static route to appear in the routing table?

a static route to the 192.168.10.0/24 network The administrative distance of 5 added to the end of the static route creates a floating static situation for a static route that goes down. Static routes have a default administrative distance of 1. This route that has an administrative distance of 5 will not be placed into the routing table unless the previously entered static route to the 192.168.10.0/24 goes down or was never entered. The administrative distance of 5 added to the end of the static route configuration creates a floating static route that will be placed in the routing table when the primary route to the same destination network goes down. By default, a static route to the 192.168.10.0/24 network has an administrative distance of 1. Therefore, the floating route with an administrative distance of 5 will not be placed into the routing table unless the previously entered static route to the 192.168.10.0/24 goes down or was never entered. Because the floating route has an administrative distance of 5, the route is preferred to an OSPF-learned route (with the administrative distance of 110) or an EIGRP-learned route (with the administrative distance of 110) to the same destination network.

A network administrator enters the following command into Router1: ip route 192.168.0.0 255.255.255.0 S0/1/0. Router1 then receives a packet that is destined for 192.168.0.22/24. After finding the recently configured static route in the routing table, what does Router1 do next to process the packet?

encapsulates the packet into a frame for the WAN link and forwards the packet out the S0/1/0 interface

Configuring the next hop static routes

far side ip and subnet mask --->near side interface ip

A Floating Static Route

floating static routes that are used to provide a backup path to a primary static or dynamic route. They have a higher administrative distance then the routing protocol used and is used if the protocol fails

Which static route statement shows a recursive IPv6 static route?

ipv6 route 2001:db8:cafe:1::/56 2001:db8:1000:10::1 In a recursive static route, only the next-hop IPv6 address is specified. As a consequence, the router must perform a recursive route table lookup to find an exit interface associated with the network of the IPv6 address.

Which command would create a valid IPv6 default route?

ipv6 route ::/0 2001:db8:acad:2::a The correct prefix and prefix length for a default route is ::/0, which matches any address. ::/128 matches only the specific address of all zeros. When creating a static route that uses a link-local address as the next hop, an exit interface must also be specified for the route to be valid.

Along with ping and traceroute, useful commands to verify static routes include:

show ip route show ip route static: verify default static route * = candidate S=static show ip route network

Use Static Route to?

1) Connect to a specific network 2) Connect a stub router 3) Summarize routing table entries 4) Create a backup route

Networks are subject to forces that can cause their status to change quite often due to:

An interface fails A service provider drops a connection Links become oversaturated An administrator enters a wrong configuration

There are three ways a host route can be added to the routing table:

Automatically installed when an IP address is configured on the router (as shown in Figures 1 and 2) Configured as a static host route Host route automatically obtained through other methods

A Standard Static Route

Both IPv4 and IPv6 support the configuration of static routes. Static routes are useful when connecting to a specific remote network.

Common IOS troubleshooting commands include:

Check your own stuff before you send up a red-start cluster. ping traceroute show ip route show ip interface brief show cdp neighbors detail ping (ip) source (interface) - useful troubleshooting command.

Default Static IPv6 Route Syntax

Default static routes are commonly used when connecting: A company's edge router to a service provider network. A router with only an upstream neighbor router. The router has no other neighbors and is therefore, referred to as a stub router.

Default Static Route

Default static routes are commonly used when connecting: An edge router to a service provider network A stub router (a router with only one upstream neighbor router)

Floating static routes are static routes that have an administrative distance greater than the administrative distance of another static route or dynamic routes. the administrative distances of some common dynamic routing protocols are:

EIGRP = 90 IGRP = 100 OSPF = 110 IS-IS = 115 RIP = 120

What command, or set of commands, would be used to determine if the following configuration on router HQ works as designed?ip route 0.0.0.0 0.0.0.0 serial 0/0/0 10ip route 0.0.0.0 0.0.0.0 serial 0/1/0

HQ(config)# interface serial 0/1/0 HQ(config-if)# shutdown HQ(config-if)# end HQ# show ip route To test a floating static route, take down the main route/link in order to see whether the backup link appears in the routing table. The show ip route command simply shows the routing table. Only one of the static routes would be shown at any one time.

Fully Specified Static Route: eliminates problems later on ... lookup

In a fully specified static route, both the exit interface and the next-hop IP address are specified. ip route: destination --->exit interface # ---->exit interface ip address

What is a characteristic of a default static route? ​

It identifies the gateway IP address to which the router sends all IP packets for which it does not have a learned or static route. default static route is simply a static route with 0.0.0.0/0 as the destination IPv4 address. Configuring a default static route creates a gateway of last resort.​

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.

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

The next hop can be identified by an IPv6 address, exit interface, or both. How the destination is specified creates one of three route types:

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 routing has three primary uses:

Providing ease of routing table maintenance in smaller networks that are not expected to grow significantly. Routing to and from stub networks. A stub network is a network accessed by a single route, and the router has only one neighbor. 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. Default routes are used to send traffic to any destination beyond the next upstream router.

Which IPv6 static route would serve as a backup route to a dynamic route learned through OSPF?

Router1(config)# ipv6 route 2001:db8:acad:1::/32 2001:db8:acad:6::2 200 The command ipv6 route 2001:db8:acad:1::/32 2001:db8:acad:6::2 200, specifies a floating static route to the 2001:db8:acad:1::/32 network with an administrative distance of 200. Since OSPF has an administrative distance of 110, the static route would only be placed in the routing table if the OSPF learned route was removed.

Summary route is:

The destination networks are contiguous and can be summarized into a single network address. The multiple static routes all use the same exit interface or next-hop IP address. one summary static route can be configured and still provide connectivity to those networks.

ip route commands:

The following parameters are required to configure static routing: network-address subnet-mask - One or both of the following parameters must also be used: ip-address -exit-intf - The distance parameter is used to create a floating static route by setting an administrative distance that is higher than a dynamically learned route.

If the IPv6 static route uses an IPv6 link-local address as the next-hop address, a fully specified static route including the exit interface must be used.

The reason a fully specified static route must be used is because IPv6 link-local addresses are not contained in the IPv6 routing table. Link-local addresses are only unique on a given link or network.

What happens to a static route entry in a routing table when the outgoing interface associated with that route goes into the down state

The static route is removed from the routing table.

What happens to a static route entry in a routing table when the outgoing interface associated with that route goes into the down state?

The static route is removed from the routing table.