- Start Here Cisco IOS Software Release Specifics for IPv6 Features
- Implementing IPv6 Addressing and Basic Connectivity
- Implementing Bidirectional Forwarding Detection for IPv6
- Implementing DHCP for IPv6
- Implementing EIGRP for IPv6
- Configuring First Hop Redundancy Protocols in IPv6
- Implementing First Hop Security in IPv6
- Implementing IS-IS for IPv6
- Implementing IPv6 for Network Management
- Implementing Mobile IPv6
- Implementing IPv6 Multicast
- Implementing Multiprotocol BGP for IPv6
- Implementing OSPFv3
- Implementing IPv6 over MPLS
- Implementing IPv6 VPN over MPLS
- Implementing QoS for IPv6
- Implementing RIP for IPv6
- Implementing Selective Packet Discard in IPv6
- Implementing Static Routes for IPv6
- Implementing Traffic Filters and Firewalls for IPv6 Security
- Implementing Tunneling for IPv6
Implementing Static Routes for IPv6
This module describes how to configure static routes for IPv6. Routing defines the paths over which packets travel in the network. Manually configured static routes may be used instead of dynamic routing protocols for smaller networks or for sections of a network that have only one path to an outside network. Lack of redundancy limits the usefulness of static routes, and in larger networks manual reconfiguration of routes can become a large administrative overhead.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Information About Implementing Static Routes for IPv6
- Static Routes
- Directly Attached Static Routes
- Recursive Static Routes
- Fully Specified Static Routes
- Floating Static Routes
Static Routes
Networking devices forward packets using route information that is either manually configured or dynamically learned using a routing protocol. Static routes are manually configured and define an explicit path between two networking devices. Unlike a dynamic routing protocol, static routes are not automatically updated and must be manually reconfigured if the network topology changes. The benefits of using static routes include security and resource efficiency. Static routes use less bandwidth than dynamic routing protocols and no CPU cycles are used to calculate and communicate routes. The main disadvantage to using static routes is the lack of automatic reconfiguration if the network topology changes.
Static routes can be redistributed into dynamic routing protocols but routes generated by dynamic routing protocols cannot be redistributed into the static routing table. No algorithm exists to prevent the configuration of routing loops that use static routes.
Static routes are useful for smaller networks with only one path to an outside network and to provide security for a larger network for certain types of traffic or links to other networks that need more control. In general, most networks use dynamic routing protocols to communicate between networking devices but may have one or two static routes configured for special cases.
Directly Attached Static Routes
In directly attached static routes, only the output interface is specified. The destination is assumed to be directly attached to this interface, so the packet destination is used as the next-hop address. This example shows such a definition:
ipv6 route 2001:DB8::/32 ethernet1/0
The example specifies that all destinations with address prefix 2001:DB8::/32 are directly reachable through interface Ethernet1/0.
Directly attached static routes are candidates for insertion in the IPv6 routing table only if they refer to a valid IPv6 interface; that is, an interface that is both up and has IPv6 enabled on it.
Recursive Static Routes
In a recursive static route, only the next hop is specified. The output interface is derived from the next hop. This example shows such a definition:
ipv6 route 2001:DB8::/32 2001:DB8:3000:1
This example specifies that all destinations with address prefix 2001:DB8::/32 are reachable via the host with address 2001:DB8:3000:1.
A recursive static route is valid (that is, it is a candidate for insertion in the IPv6 routing table) only when the specified next hop resolves, either directly or indirectly, to a valid IPv6 output interface, provided the route does not self-recurse, and the recursion depth does not exceed the maximum IPv6 forwarding recursion depth.
A route self-recurses if it is itself used to resolve its own next hop. For example, suppose we have the following routes in the IPv6 routing table:
IPv6 Routing Table - 9 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
U - Per-user Static route
I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
R 2001:DB8::/32 [130/0]
via ::, Serial2/0
B 2001:DB8:3000:0/16 [200/45]
Via 2001:DB8::0104
The following examples defines a recursive IPv6 static route:
ipv6 route 2001:DB8::/32 2001:0BD8:3000:1
This static route will not be inserted into the IPv6 routing table because it is self-recursive. The next hop of the static route, 2001:DB8:3000:1, resolves via the BGP route 2001:DB8:3000:0/16, which is itself a recursive route (that is, it only specifies a next hop). The next hop of the BGP route, 2001:DB8::0104, resolves via the static route. Therefore, the static route would be used to resolve its own next hop.
It is not normally useful to manually configure a self-recursive static route, although it is not prohibited. However, a recursive static route that has been inserted in the IPv6 routing table may become self-recursive as a result of some transient change in the network learned through a dynamic routing protocol. If this occurs, the fact that the static route has become self-recursive will be detected and it will be removed from the IPv6 routing table, although not from the configuration. A subsequent network change may cause the static route to no longer be self-recursive, in which case it will be reinserted in the IPv6 routing table.
 Note |
In Cisco IOS Release 12.2(15)T and older releases, IPv6 recursive static routes are checked at one-minute intervals. Therefore, a recursive static route may take up to a minute to be inserted into the routing table once its next hop becomes valid. Likewise, it may take a minute or so for the route to disappear from the table if its next hop becomes invalid. |
Fully Specified Static Routes
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.
Floating Static Routes
Floating static routes are static routes that are used to back up dynamic routes learned through configured routing protocols. A floating static route is configured with a higher administrative distance than the dynamic routing protocol it is backing up. As a result, the dynamic route learned through the routing protocol is always used in preference to the floating static route. If the dynamic route learned through the routing protocol is lost, the floating static route will be used in its place. The following example defines a floating static route:
ipv6 route 2001:DB8:/32 ethernet1/0 2001:DB8:3000:1 210
Any of the three types of IPv6 static routes can be used as a floating static route. A floating static route must be configured with an administrative distance that is greater than the administrative distance of the dynamic routing protocol, because routes with smaller administrative distances are preferred.
Note |
By default, static routes have smaller administrative distances than dynamic routes, so static routes will be used in preference to dynamic routes. |
How to Implement Static Routes for IPv6
- Configuring a Static IPv6 Route
- Configuring a Recursive IPv6 Static Route to Use a Default IPv6 Static Route
- Configuring a Floating Static IPv6 Route
- Verifying Static IPv6 Route Configuration and Operation
Configuring a Static IPv6 Route
DETAILED STEPS
Configuring a Recursive IPv6 Static Route to Use a Default IPv6 Static Route
By default, a recursive IPv6 static route will not resolve using the default route (::/0). Perform this task to restore legacy behavior and allow resolution using the default route.
DETAILED STEPS
Configuring a Floating Static IPv6 Route
DETAILED STEPS
Verifying Static IPv6 Route Configuration and Operation
- show ipv6 static [ipv6-address | ipv6-prefix / prefix-length][interface interface-type interface-number] [recursive] [detail]
- show ipv6 route [ipv6-address | ipv6-prefix / prefix-length | protocol | interface-type interface-number
DETAILED STEPS
Examples
Sample Output from the ipv6 route Command
The following example shows how to configure a directly attached static route through a point-to-point interface.
Router(config)# ipv6 route 2001:DB8::/32 serial 0
The following example shows how to configure a directly attached static route on a broadcast interface.
Router(config)# ipv6 route 2001:DB8::1/32 ethernet1/0
The following example shows how to configure a fully specified static route on a broadcast interface.
Router(config)# ipv6 route 2001:DB8::1/32 ethernet1/0 fe80::1
In the following example, a static route is being configured to a specified next-hop address, from which the output interface is automatically derived.
Router(config)# ipv6 route 2001:DB8::/32 2001:DB8:2002:1>>
Sample Output from the show ipv6 static Command when No Options Are Specified in the Command Syntax
When no options are specified in the command, those routes installed in the IPv6 routing table are marked with an asterisk, as shown in the following example:
Router# show ipv6 static
IPv6 Static routes
Code: * - installed in RIB
* 2001:DB8:3000:0/16, interface Ethernet1/0, distance 1
* 2001:DB8:4000:0/16, via nexthop 2001:DB8:1:1, distance 1
2001:DB8:5000:0/16, interface Ethernet3/0, distance 1
* 2001:DB8:5555:0/16, via nexthop 2001:DB8:4000:1, distance 1
2001:DB8:5555:0/16, via nexthop 2001:DB8:9999:1, distance 1
* 2001:DB8:5555:0/16, interface Ethernet2/0, distance 1
* 2001:DB8:6000:0/16, via nexthop 2001:DB8:2007:1, interface Ethernet1/0, distance 1
Sample Output from the show ipv6 static Command with the IPv6 Address and Prefix Command
When the ipv6-address or ipv6-prefix / prefix-length argument is specified, only information about static routes for that address or network is displayed. The following is sample output from the show ipv6 staticcommand when entered with the IPv6 prefix 2001:DB8:200::/35:
Router# show ipv6 static 2001:DB8:5555:0/16
IPv6 Static routes
Code: * - installed in RIB
* 2001:DB8:5555:0/16, via nexthop 2001:DB8:4000:1, distance 1
2001:DB8:5555:0/16, via nexthop 2001:9999:1, distance 2
* 2001:DB8:5555:0/16, interface Ethernet2/0, distance 1
Sample Output from the show ipv6 static interface Command
When an interface is supplied, only those static routes with the specified interface as outgoing interface are displayed. The interface keyword may be used with or without the IPv6 address and prefix specified in the show ipv6 static command.
Router# show ipv6 static interface ethernet3/0
IPv6 Static routes
Code: * - installed in RIB
Sample Output from the show ipv6 static recursive Command
When the recursive keyword is specified in the show ipv6 static command, only recursive static routes are displayed. The recursive keyword is mutually exclusive with the interface keyword, but it may be used with or without the IPv6 prefix included in the command syntax.
Router# show ipv6 static recursive
IPv6 Static routes
Code: * - installed in RIB
* 2001:DB8:4000:0/16, via nexthop 2001:DB8:1:1, distance 1
* 2001:DB8:5555:0/16, via nexthop 2001:DB8:4000:1, distance 2
2001:DB8:5555:0/16, via nexthop 2001:DB8:9999:1, distance 3
Sample Output from the show ipv6 static detail Command
When the detail keyword is specified, the following additional information is also displayed:
- For valid recursive routes, the output path set, and maximum resolution depth
- For invalid recursive routes, the reason why the route is not valid.
- For invalid direct or fully specified routes, the reason why the route is not valid.
Router# show ipv6 static detail
IPv6 Static routes
Code: * - installed in RIB
* 2001:DB8:3000:0/16, interface Ethernet1/0, distance 1
* 2001:DB8:4000:0/16, via nexthop 2001:DB8:2001:1, distance 1
Resolves to 1 paths (max depth 1)
via Ethernet1/0
2001:DB8:5000:0/16, interface Ethernet3/0, distance 1
Interface is down
* 2001:DB8:5555:0/16, via nexthop 2001:DB8:4000:1, distance 1
Resolves to 1 paths (max depth 2)
via Ethernet1/0
2001:DB8:5555:0/16, via nexthop 2001:DB8:9999:1, distance 1
Route does not fully resolve
* 2001:DB8:5555:0/16, interface Ethernet2/0, distance 1
* 2001:DB8:6000:0/16, via nexthop 2001:DB8:2007:1, interface Ethernet1/0, distance 1
Sample Output from the show ipv6 route Command
In the following example, the show ipv6 route command is used to verify the configuration of a static route through a point-to-point interface:
Router# show ipv6 route
IPv6 Routing Table - 9 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
U - Per-user Static route
I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
S 2001:DB8::/32 [1/0]
via ::, Serial2/0
In the following example, the show ipv6 route command is used to verify the configuration of a static route on a multiaccess interface. An IPv6 link-local address--FE80::1--is the next-hop router.
Router# show ipv6 route
IPv6 Routing Table - 11 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
U - Per-user Static route
I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
S 2001:DB8::/32 [1/0]
via FE80::1, Ethernet0/0
To display all static routes in the IPv6 routing table, use the show ipv6 route static command is used with static as the value of the protocol argument:
Router# show ipv6 route static
IPv6 Routing Table - 330 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
U - Per-user Static route
I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
S 2001:DB8::/32 [1/0]
via ::, Tunnel0
S 3FFE:C00:8011::/48 [1/0]
via ::, Null0
S ::/0 [254/0]
via 2001:DB8:2002:806B, Null
Sample Output from the debug ipv6 routing Command
In the following example, the debug ipv6 routing command is used to verify the installation of a floating static route into the IPv6 routing table when an IPv6 RIP route is deleted. The floating static IPv6 route was previously configured with an administrative distance value of 130. The backup route was added as a floating static route because RIP routes have a default administrative distance of 120, and the RIP route should be the preferred route. When the RIP route is deleted, the floating static route is installed in the IPv6 routing table.
Router# debug ipv6 routing
*Oct 10 18:28:00.847: IPv6RT0: rip two, Delete 2001:DB8::/32 from table
*Oct 10 18:28:00.847: IPv6RT0: static, Backup call for 2001:DB8::/32
*Oct 10 18:28:00.847: IPv6RT0: static, Add 2001:DB8::/32 to table
*Oct 10 18:28:00.847: IPv6RT0: static, Adding next-hop :: over Serial2/0 for 2001:DB8::/32, [130/0]
Configuration Examples for Implementing Static Routes for IPv6
Static routes may be used for a variety of purposes. Common usages include the following:
In many cases, alternative mechanisms exist within Cisco IOS software to achieve the same objective. Whether to use static routes or one of the alternative mechanisms depends on local circumstances.
- Example Configuring Manual Summarization
- Example Configuring Traffic Discard
- Example Configuring a Fixed Default Route
- Example Configuring a Floating Static Route
Example Configuring Manual Summarization
The following example shows a static route being used to summarize local interface prefixes advertised into RIP. The static route also serves as a discard route, discarding any packets received by the router to a 2001:DB8:1::/48 destination not covered by a more specific interface prefix.
Router> enable Router# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)# interface ethernet0/0 Router(config-if)# ipv6 address 2001:DB8:2:1234/64 Router(config-if)# exit Router(config)# Router(config)# interface ethernet1/0 Router(config-if)# ipv6 address 2001:DB8:3:1234/64 Router(config-if)# exit Router(config)# interface ethernet2/0 Router(config-if)# ipv6 address 2001:DB8:4:1234/64 Router(config-if)# exit Router(config)# interface ethernet3/0 Router(config-if)# ipv6 address 2001:DB8::1234/64 Router(config-if)# ipv6 rip one enable Router(config-if)# exit Router(config)# ipv6 router rip one Router(config-rtr)# redistribute static Router(config-rtr)# exit Router(config)# ipv6 route 2001:DB8:1:1/48 null0 Router(config)# end 00:01:30: %SYS-5-CONFIG_I: Configured from console by console Router# show ipv6 route static IPv6 Routing Table - 3 entries Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP U - Per-user Static route I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 S 2001:DB8:1::/48 [1/0] via ::, Null0
Example Configuring Traffic Discard
Configuring a static route to point at interface null0 may be used for discarding traffic to a particular prefix. For example, if it is required to discard all traffic to prefix 2001:DB8:42:1/64, the following static route would be defined:
Router> enable Router# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)# ipv6 route 2001:DB8:42:1::/64 null0 Router(config)# end
Example Configuring a Fixed Default Route
A default static route is often used in simple router topologies. In the following example, a router is connected to its local site via Ethernet0/0 and to the main corporate network via Serial2/0 and Serial3/0. All nonlocal traffic will be routed over the two serial interfaces.
Router(config)# interface ethernet0/0 Router(config-if)# ipv6 address 2001:DB8:17:1234/64 Router(config-if)# exit Router(config)# interface Serial2/0 Router(config-if)# ipv6 address 2001:DB8:1:1234/64 Router(config-if)# exit Router(config)# interface Serial3/0 Router(config-if)# ipv6 address 2001:DB8:2:124/64 Router(config-if)# exit Router(config)# ipv6 route ::/0 Serial2/0 Router(config)# ipv6 route ::/0 Serial3/0 Router(config)# end Router# 00:06:30: %SYS-5-CONFIG_I: Configured from console by console Router# show ipv6 route static IPv6 Routing Table - 7 entries Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP U - Per-user Static route I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 S ::/0 [1/0] via ::, Serial2/0 via ::, Serial3/0
Example Configuring a Floating Static Route
A floating static route often is used to provide a backup path in the event of connectivity failure. In the following example, the router has connectivity to the network core via Serial2/0 and learns the route 2001:DB8:1:1/32 via IS-IS. If the Serial2/0 interface fails, or if route 2001:DB8:1:1/32 is no longer learned via IS-IS (indicating loss of connectivity elsewhere in the network), traffic is routed via the backup ISDN interface.
Router> enable Router# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)# interface ethernet0/0 Router(config-if)# ipv6 address 2001:DB8:17:1234/64 Router(config-if)# exit Router(config)# interface Serial2/0 Router(config-if)# ipv6 address 2001:DB8:1:1234/64 Router(config-if)# ipv6 router isis Router(config-if)# exit Router(config)# router isis Router(config-router)# net 42.0000.0000.0000.0001.00 Router(config-router)# exit Router(config)# interface BRI1/0 Router(config-if)# encapsulation ppp Router(config-if)# ipv6 enable Router(config-if)# isdn switch-type basic-net3 Router(config-if)# ppp authentication chap optional Router(config-if)# ppp multilink Router(config-if)# exit Router(config)# dialer-list 1 protocol ipv6 permit Router(config)# ipv6 route 2001:DB8:1::/32 BRI1/0 200 Router(config)# end Router# 00:03:07: %SYS-5-CONFIG_I: Configured from console by console 2001:DB8:5000:)/16, interface Ethernet3/0, distance 1
Additional References
Related Documents
| Related Topic |
Document Title |
|---|---|
| IP static route configuration |
" Protocol-Independent Routing," Cisco IOS IP Routing Protocols Configuration Guide |
| IP static route commands: complete command syntax, command mode, defaults, usage guidelines, and examples |
Cisco IOS IP Routing Protocols Command Reference |
| IPv6 supported feature list |
" Start Here: Cisco IOS Software Release Specifics for IPv6 Features ," Cisco IOS IPv6 Configuration Guide |
| IPv6 commands: complete command syntax, command mode, defaults, usage guidelines, and examples |
Cisco IOS IPv6 Command Reference |
Standards
| Standards |
Title |
|---|---|
| No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
-- |
MIBs
| MIBs |
MIBs Link |
|---|---|
| None |
To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL: |
RFCs
| RFCs |
Title |
|---|---|
| No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
-- |
Technical Assistance
| Description |
Link |
|---|---|
| The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for Implementing Static Routes for IPv6
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
| Table 1 | Feature Information for Implementing Static Routes for IPv6 |
| Feature Name |
Releases |
Feature Information |
|---|---|---|
| IPv6 Routing--Static Routing |
12.0(22)S 12.2(14)S 12.2(28)SB 12.2(25)SG 12.2(33)SRA 12.2(17a)SX1 12.2(2)T 12.3 12.3(2)T 12.4 12.4(2)T 15.0(1)S |
Static routes are manually configured and define an explicit path between two networking devices. |
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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
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