Chapter 4

• Static routes


  Commonly implemented on a network, even when there is a dynamic routing protocol configured

  
• Types of static routes

  • Standard static route
  • Default static route
  • Floating static route
  • Summary static route

  
• Static routes


  Configured using the ip route and ipv6 route global configuration commands

  
• Next-hop options when configuring a static route


  • 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)

  
• Configuring IPv4 static routes

  ip route network-address subnet-mask { ip-address | exit-intf [ip-address]} [distance]

  
• Configuring IPv6 static routes

  ipv6 route ipv6-prefix/prefix-length {ipv6-address | exit-intf [ipv6-address]} [distance]

  
• Dual-stack topology


  • No static routes configured for either IPv4 or IPv6

  
• R1 can ping R2, but cannot ping the R3 LAN
• Configuring IPv4 next-hop static route on R1

  1. ip route 172.16.1.0 255.255.255.0 172.16.2.2

  2. ip route 192.168.1.0 255.255.255.0 172.16.2.2

  3. ip route 192.168.2.0 255.255.255.0 172.16.2.2

  
• Configuring IPv6 next-hop static route on R1

  1. ipv6 route 2001:db8:acad:1::/64 2001:db8:acad:2::2

  2. ipv6 route 2001:db8:cafe:1::/64 2001:db8:acad:2::2

  3. ipv6 route 2001:db8:cafe:2::/64 2001:db8:acad:2::2

  
• Configuring IPv4 directly connected static route on R1

  1. ip route 172.16.1.0 255.255.255.0 s0/1/0

  2. ip route 192.168.1.0 255.255.255.0 s0/1/0

  3. ip route 192.168.2.0 255.255.255.0 s0/1/0

  
• Configuring IPv6 directly connected static route on R1

  1. ipv6 route 2001:db8:acad:1::/64 s0/1/0

  2. ipv6 route 2001:db8:cafe:1::/64 s0/1/0

  3. ipv6 route 2001:db8:cafe:2::/64 s0/1/0

  
• Fully specified static route

  Both the exit interface and the next-hop IP address are specified

  
• When the exit interface is an Ethernet network, it is recommended to use a fully specified static route that includes both the exit interface and the next-hop address

  
• Configuring IPv6 fully specified static route on R1

  ipv6 route 2001:db8:acad:1::/64 s0/1/0 2001:db8:acad:2::2

  
• Link-local addresses


  Not contained in the IPv6 routing table, only unique on a given link or network

  
• When using an IPv6 link-local address as the next-hop address, a fully specified static route must be used

  
• Commands to verify static routes

  • show ip route static
  • show ip route network
  • show running-config | section ip route

  
• Default route


  A static route that matches all packets, used as the Gateway of Last Resort

  
• Routers commonly use default routes that are either configured locally or learned from another router
• Default static routes are commonly used when connecting an edge router to a service provider network, or a stub router

  
• Default static route


  A static route that matches all packets. A single default route represents any network that is not in the routing table.

  
• Default static routes


  • Commonly used when connecting an edge router to a service provider network, or a stub router (a router with only one upstream neighbor router)

  
• Configure IPv4 default static route


  ip route 0.0.0.0 0.0.0.0 {ip-address | exit-intf}

  
• Configure IPv6 default static route


  ipv6 route ::/0 {ipv6-address | exit-intf}

  
• Configure IPv4 default static route


  • ip route 0.0.0.0 0.0.0.0 172.16.2.2

  
• Configure IPv6 default static route


  • ipv6 route ::/0 2001:db8:acad:2::2

  
• Floating static route


  A static route used to provide a backup path to a primary static or dynamic route. The floating static route is only used when the primary route is not available.

  
• Administrative distance


  Represents the trustworthiness of a route. If multiple paths to the destination exist, the router will choose the path with the lowest administrative distance.
• Configure IPv4 floating static route


  ip route 0.0.0.0 0.0.0.0 10.10.10.2 5

  
• Configure IPv6 floating static route

  ipv6 route ::/0 2001:db8:feed:10::2 5

  
• Host route


  An IPv4 address with a 32-bit mask, or an IPv6 address with a 128-bit mask

  
• Ways a host route can be added to the routing table

  • Automatically installed when an IP address is configured on the router
  • Configured as a static host route
  • Host route automatically obtained through other methods

  
• Configure IPv4 static host route

  ip route 209.165.200.238 255.255.255.255 198.51.100.2

  
• Configure IPv6 static host route

  ipv6 route 2001:db8:acad:2::238/128 2001:db8:acad:1::2

  
• Configure IPv6 static host route with link-local next-hop

  ipv6 route 2001:db8:acad:2::238/128 fe80::1 GigabitEthernet0/0