IPv 6 Routing Describing IPv 6 Routing 2

IPv 6 Routing

Describing IPv 6 Routing 2

IPv 6 Routing Table l l l IPv 6 routing protocols still use the longest-match prefix as the oruting algorithm for route selection as their equivalent did in IPv 4. Ipv 6 routing table is handled and managed separately from the IPv 4 routing table when both protocols are enabled simultaneously. IPv 6 unicast-routing l Enabled on Cisco routers router start forwarding IPv 6 packets between its interfaces using IPv 6 routing table. IPv 6 Routing 3

Administrative Distance l Administrative distance remains same as in IPv 4 as displayed by the following table: IPv 6 Routing 4

Displaying IPv 6 Routing Table Following addresses are automatically inserted in the routing table: Link-local prefix Multicast-prefix Default ipv 6 route IPv 6 Routing 5

Static Routing IPv 6 Routing

Static Routing Overview l l Static routes are manually configured and define an explicit path between two networking devices. Restrictions for Implementing Static Routes for IPv 6: l l IPv 6 static routes do not currently support the tag and permanent keywords of the IPv 4 ip route command. IPv 6 does not currently support inserting static routes into virtual routing and forwarding (VRF) tables. IPv 6 Routing 7

Static IPv 6 Routes l l l Prerequisite for static IPv 6 routes: l Before configuring the router with a static IPv 6 route: l Enable forwarding of IPv 6 packets using the ipv 6 unicastrouting global configuration command l enable IPv 6 on at least one interface l configure an IPv 6 address on that interface. 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. Types of static routes 1. Directly attached static routes 2. Fully specified static routes 3. Floating static routes IPv 6 Routing 8

Directly Attached Static Routes l l l 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. ipv 6 route 2001: 0 DB 8: : /32 ethernet 1/0 l all destinations with address prefix 2001: 0 DB 8: : /32 are directly reachable via interface Ethernet 1/0. l Directly attached static routes are candidates for insertion in the IPv 6 routing table only if they refer to a valid IPv 6 interface; that is, an interface that is both up and has IPv 6 enabled on it. IPv 6 Routing 9

Fully Specified Static Routes l l l 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. l l ipv 6 route 2001: DB 8: /32 ethernet 1/0 2001: 0 DB 8: 3000: 1 A fully specified route is valid (that is, a candidate for insertion into the IPv 6 routing table) when the specified IPv 6 interface is IPv 6 -enabled and up. IPv 6 Routing 10

Floating Static Routes l l l 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. l ipv 6 route 2001: DB 8: /32 ethernet 1/0 2001: 0 DB 8: 3000: 1 210 Any of the three types of IPv 6 static routes can be used as a floating static route. Note: By default, static routes have smaller administrative distances than dynamic routes, so static routes will be used in preference to dynamic routes. IPv 6 Routing 11

Implementing Static Routes for IPv 6 1. Configuring a Static IPv 6 Route IPv 6 Routing 12

Examples l Directly Attached Static Route through Point-to-Point Interface l l Directly Attached Static Route on Broadcast Interface l l Router(config)# ipv 6 route 2001: 0 DB 8: : /32 serial 0 Router(config)# ipv 6 route 2001: 0 DB 8: : 1/32 ethernet 1/0 Fully Specified Static Route on Broadcast Interface l Router(config)# ipv 6 route 2001: 0 DB 8: : 1/32 ethernet 1/0 fe 80: : 1 IPv 6 Routing 13

Configuring a Floating Static IPv 6 Route STEPS l 1. 2. 3. enable configure terminal ipv 6 route ipv 6 -prefix/prefix-length {ipv 6 address | interface-type interface-number [ipv 6 address]} [administrative-distance] [administrative-multicast-distance | unicast | multicast] [tag tag] IPv 6 Routing 14

Verifying Static IPv 6 Route Configuration and Operation l l show ipv 6 static l To display a set of static routes and the installed status of each, that is, whether an entry for each route appears in the IPv 6 routing table. show ipv 6 route l To confirm that installed routes are in the IPv 6 routing table and that each route definition reflects the expected cost and metric. l l If a static route that you have configured does not appear in the IPv 6 routing table, it is possible that there is a lower administrative distance from another source in the table, such as from a routing protocol. If a lower administrative distance exists, the static route is "floating" and will be inserted into the routing table only when the route learned through the routing protocol disappears. I IPv 6 Routing 15

show ipv 6 static l Router# show ipv 6 static IPv 6 Static routes Code: * - installed in RIB * 2001: 0 DB 8: 3000: 0/16, interface Ethernet 1/0, distance 1 * 2001: 0 DB 8: 4000: 0/16, via nexthop 2001: 0 DB 8: 1: 1, distance 1 2001: 0 DB 8: 5000: 0/16, interface Ethernet 3/0, distance 1 * 2001: 0 DB 8: 5555: 0/16, via nexthop 2001: 0 DB 8: 4000: 1, distance 1 2001: 0 DB 8: 5555: 0/16, via nexthop 2001: 0 DB 8: 9999: 1, distance 1 * 2001: 0 DB 8: 5555: 0/16, interface Ethernet 2/0, distance 1 * 2001: 0 DB 8: 6000: 0/16, via nexthop 2001: 0 DB 8: 2007: 1, interface Ethernet 1/0, distance 1 IPv 6 Routing 16

Implementing OSPF for IPv 6 OSPFv 3 IPv 6 Routing

Similarities Between OSPFv 2 and OSPFv 3 IPv 6 Routing 18

Prerequisites for Implementing OSPF for IPv 6 l Before you enable OSPF for IPv 6 on an interface, you must do the following: l l Complete the OSPF network strategy and planning for your IPv 6 network. For example, you must decide whether multiple areas are required. Enable IPv 6 unicast routing. Enable IPv 6 on the interface. Configure the IP Security (IPSec) secure socket application program interface (API) on OSPF for IPv 6 in order to enable authentication and encryption. IPv 6 Routing 19

Differences Between OSPFv 2 and OSPFv 3 l In OSPF for IPv 6, a routing process does not need to be explicitly created. l l In OSPF for IPv 6, each interface must be enabled using commands in interface configuration mode. l l Enabling OSPF for IPv 6 on an interface will cause a routing process, and its associated configuration, to be created. This feature is different from OSPF version 2, in which interfaces are indirectly enabled using the router configuration mode. Some of the notable changes include: l l platform-independent implementation protocol processing per-link rather than per-node explicit support for multiple instances per link changes in authentication and packet format IPv 6 Routing 20

Differences Between OSPFv 2 and OSPFv 3 l OSPFv 3 runs over a link l l IPv 6 uses the term link to indicate a communication facility or medium over which nodes can communicate at the link layer OSPF interfaces connect to links instead of to IP subnets. OSPF for IPv 6 therefore runs per-link instead of the IPv 4 behavior of per-IP-subnet, and the terms network and subnet are generally replaced by the term link. This change affects the receiving of OSPF protocol packets, and the contents of hello packets and network LSAs. IPv 6 Routing 21

Differences Between OSPFv 2 and OSPFv 3 l Link-local addresses are used l l OSPFv 3 uses IPv 6 link-local addresses to identify the OSPFv 3 adjacency neighbors. When configuring the ipv 6 ospf neighbor command, the IPv 6 address used must be the link -local address of the neighbor. IPv 6 Routing 22

Differences Between OSPFv 2 and OSPFv 3 l Multiple OSPFv 3 instance support l l l Separate autonomous systems, each running OSPF, use a common link. A single link could belong to multiple areas. OSPFv 3 uses a new field, called the Instance ID, to allow multiple instances per link. To have two instances talk to each other, they must share the same instance ID. By default, the instance ID is set to 0. Multicast addresses l l FF 02: : 5 —Represents all shortest path first (SPF) routers on the linklocal scope, equivalent to 224. 0. 0. 5 in OSPFv 2. FF 02: : 6 —Represents all designated routers (DRs) on the link-local scope, equivalent to 224. 0. 0. 6 in OSPFv 2. IPv 6 Routing 23

New LSA Types for IPv 6 l Link LSAs (Type 8) l Have local-link flooding scope and are never flooded beyond the link with which they are associated. l Link LSAs provide the link-local address of the router to all other routers attached to the link, inform other routers attached to the link of a list of IPv 6 prefixes to associate with the link, and allow the router to assert a collection of Options bits to associate with the network LSA that will be originated for the link. IPv 6 Routing 24

New LSA Types for IPv 6 l Intra-Area-Prefix LSAs (Type 9) l l A router can originate multiple intra-area-prefix LSAs for each router or transit network, each with a unique link-state ID. The link-state ID for each intra-area-prefix LSA describes its association to either the router LSA or the network LSA and contains prefixes for stub and transit networks. IPv 6 Routing 25

Implementing and Verifying OSPFv 3 IPv 6 Routing

IPv 6 Configuration l l l Before configuring OSPFv 3, IPv 6 must be enabled with the ipv 6 unicast-routing global configuration command. Use the ipv 6 address/prefix-length [eui-64] interface configuration command to configure an IPv 6 address for an interface and enable IPv 6 processing on the interface. The eui-64 parameter forces the router to complete the addresses' low-order 64 -bits using an EUI-64 format interface ID. IPv 6 Routing 27

Steps to Configure OSPF for IPv 6 1. 2. 3. 4. 5. Complete the OSPF network strategy and planning for your IPv 6 network. For example, you must decide whether multiple areas are required. Enable IPv 6 unicast routing using the ipv 6 unicast-routing command. Enable IPv 6 on the interface using the ipv 6 ospf area command. (Optional) Configure OPSFv 3 interface specific settings, including area, router priority, and OSPFv 3 path cost. (Optional) Configure routing specifics from router configuration mode, including router priority, route summarization, and so on. IPv 6 Routing 28

Enabling OSPFv 3 on an Interface l Most of the OSPFv 3 configuration is done on the interface. IPv 6 Routing 29

Configuring OSPFv 3 Routing Specifics l OSPFv 3 routing specifics are configured from router configuration mode. l l l For an IPv 6 -only router, a router ID parameter must be defined in the OSPFv 3 configuration as an IPv 4 address using the router-id router configuration command. OSPFv 3 uses a 32 -bit number for a router ID. The OSPFv 3 router ID can be expressed in dotted decimal, allowing easy overlay of an OSPFv 3 network on an existing OSPFv 2 network. If IPv 4 is configured on the router, by default, the router ID is chosen in the same way as it is with OSPFv 2. The highest IPv 4 address configured on a loopback interface becomes the router ID. If no loopback interfaces are configured, the highest address on any other interface becomes the router ID. IPv 6 Routing 30

OSPFv 3 Route Summarization Before Summarization: After Summarization: IPv 6 Routing 31

OSPFv 3 Configuration Example IPv 6 Routing 32

OSPFv 3 Configuration Example The following example configures an OSPF routing process 109 to run on the interface and puts it in area 1: ipv 6 ospf 109 area 1 IPv 6 Routing 33