ipv6 routing

What is IPv6 Route Next-Hop Option? – Explanation

What is IPv6 Route Next-Hop Option? – Explanation

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As we already discussed, What is a Next-Hop in the Network? The article is a routing term for the next neighboring router a data packet can go through.

The IPv6 route next-hop is along with the series of routers connected simultaneously in a network and is the next possible destination for a data packet. Figure 1 displays the topology, and Figure 2 shows the routing tables of Router0, Router1, and Router2.

Each router maintains its routing table with an IPv6 route next-hop address, calculated based on the routing protocol and associated metric. The routers are the most critical network device among many devices.

To maintain information about other routers and networks in its routing table, the lowest metric in the routing table is known as the next-hop or the next optimal router.

When a packet passes a router, the hop count increases by one. For example, if a destination is 5 hops away from the source, the packet has to pass 5 different routers to reach it.

Also, for every router, the next router is connected to it with the best metric, such as the next hop in its routing table. Examine the following topology and then check the routing table of all routers in Figure 2.

You can check that each router has entries for its directly connected networks and their associated local addresses. Each router does not know about any network beyond its directly connected interfaces. For example, Router0 does not know networks:

  • 2001:AD10:110B:0001::/64 – Local Subnetwork of Router1
  • 2001:AD10:110B:0002::/64 – Local Subnetwork of Router2
  • 2001:AD10:110B:0004::/64 – IPv6 subnetwork between Router1 and Router2

Figure 3 displays a ping result from Router0 to Router1 using IP addresses 2001:AD10:110B:0003::1, 2001:AD10:110B:0004:: , and 2001:AD10:110B:0001:: you can see that a ping to IP address 2001:AD10:110B:0003::1 is successful because network 2001:AD10:110B:0003::1/64 is available in the routing table as a directly connected router. The ping result from Router0 to IP addresses 2001:AD10:110B:0004::, and 2001:AD10:110B:0001::  are unsuccessful because the network is not available in the routing table of Router0. So, Router0 don’t know where to send the ping request, resulting in an unsuccessful ping result.

What is ipv6 route Command? – Brief Explanation

What is ipv6 route Command? – Brief Explanation

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If you learn how to configure a static route for IPv4 then you can easily configure and understand the IPv6 static routes. The configuration and syntax for IPv6 static routes are similar to IPv4 static routes. There is only a minor difference between IPv4 and IPv6 static routes. The static routes for IPv6 are configured using the ipv6 route command in global configuration mode. The common syntax for the ipv6 route command is following:

Router(config)# ipv6 route ipv6-prefix/prefix-length { ipv6-address |exit-interface }

The parameter of the command is mostly identical to the IPv4 version of the command. We can configure the following types of the route using ipv6 route command:

  • Standard IPv6 static route – This is the same as standard IPv4 routing.
  • Default IPv6 static route – This is also the same as the default static ipv4 route
  • Floating IPv6 static route – This is a floating static route also the same to an ipv4 floating route.
  • Summary IPv6 static route – this route is also the same as the summary ipv4 static route.

To configure ipv6 routing the ipv6 unicast-routing must be configured to enable the router to forward IPv6 packets. The parameter description of ipv6 routing command is the following:

Ipv6-prefix – This is the first parameter. It specifies the destination network address that required adding into the routing table.

prefix-length – prefix length of the remote network to add into the routing table.

Ipv6-address – This is the IP address of the next-hop router. This creates recursive route lookup.

Exit-Interface –  This is the exit interface to forward packets to the destination network also referred to as directly connected static route. Typically this is used when connecting in a point-to-point configuration.

Enable ipv6 Routing on the Router

Enabling ipv6 unicast routing on the router is important. Without enabling  ipv6 unicast ipv6 static routing is not possible, the enabling process is following.

  • Router0>enable
  • Router0#configure terminal
  • Router0(config)#ipv6 unicast routing
  • Router0(config)#exit
  • Router0# wr
  • Building configuration…
  • [OK]
  • Router0>