CCNP ROUTE: 3. RIP Next Generation (RIPng)

Compared to RIPv2, RIPng differs in a few ways:

- UDP Port is 521, instead of 520.
- Multicast Update destination is FF02::9, instead of 224.0.0.9.
- Authentication uses IPv6 AH/ESP instead of RIP-specific auth.

The overall operation of RIPng closely matches RIP-2. In both, routers send periodic full updates with all routes, except for routes omitted due to Split Horizon rules.
No neighbor relationships occur; the continuing periodic Updates, on a slightly-variable 30 second period, also serve the purpose of confirming that the neighboring router still works.
Metric meaning infinity is still 16.

Configuration differences:

1) The big difference between RIP-2 and RIPng configuration is that RIPng discards the old RIP network command in deference to the ipv6 rip name enable interface subcommand, which enables RIPng on the interface.

2) Another difference relates to routing: IOS routes IPv4 by default (due to a default global configuration command of ip routing), but IOS does not route IPv6 by default (a default of no ipv6 unicast routing).

3) RIPng allows multiple RIPng processes on a single router, so IOS requires that each RIPng process is given a text name that identifies each RIPng process.

Note: As with RIPv1 and RIPv2, for any interface on which RIPng has been enabled, the RIP process does three main actions. First, it starts sending RIP updates on that interface. It also starts processing any RIP updates received on that interface. Finally, it advertises about the connected routes on that interface.

Configuration steps:

Step 1. Enable IPv6 routing with the ipv6 unicast-routing global command.
Step 2. Enable RIPng using the ipv6 router rip name global configuration command. The name must be unique on a router but does not need to match neighboring routers.
Step 3. Enable IPv6 on the interface, typically with one of these two methods:
    - Configure an IPv6 unicast address on each interface using the ipv6 address address/prefix-length [eui-64] interface command.
    - Configure the ipv6 enable command, which enables IPv6 and causes the router to derive its link local address.
Step 4. Enable RIP on the interface with the ipv6 rip name enable interface subcommand (where the name matches the ipv6 router rip name global configuration command).

Step 1: We already have ipv6 routing enabled.
!
ipv6 unicast-routing
!

Step 2:
R1(config)#ipv6 router rip testrip
R1(config-rtr)#

Steps 3 & 4:
R1(config)#interface serial 0/1
R1(config-if)#ipv6 rip testrip enable

R1(config)#interface serial 0/0   
R1(config-if)#ipv6 rip testrip enable 
       
R1(config)#interface fastEthernet 0/0
R1(config-if)#ipv6 rip testrip enable

Let's do the same on R4:

R4(config)#ipv6 unicast-routing
R4(config)#ipv6 router rip testrip
R4(config)#interface serial 0/0
R4(config-if)#ipv6 rip testrip enable

RIPng verification commands:

R4#show ipv6 route rip
IPv6 Routing Table - 6 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
R   2000:0:0:1::/64 [120/2]
     via FE80::C201:12FF:FE0C:0, Serial0/0
R   2000:0:0:2::/64 [120/2]
     via FE80::C201:12FF:FE0C:0, Serial0/0

R4#show ipv6 protocols
IPv6 Routing Protocol is "connected"
IPv6 Routing Protocol is "static"
IPv6 Routing Protocol is "rip testrip"
  Interfaces:
    Serial0/0
  Redistribution:
    None

R4#show ipv6 rip
RIP process "testrip", port 521, multicast-group FF02::9, pid 40
     Administrative distance is 120. Maximum paths is 16
     Updates every 30 seconds, expire after 180
     Holddown lasts 0 seconds, garbage collect after 120
     Split horizon is on; poison reverse is off
     Default routes are not generated
     Periodic updates 16, trigger updates 1
  Interfaces:
    Serial0/0
  Redistribution:
    None

R4#show ipv6 rip next-hops
 RIP process "testrip", Next Hops
  FE80::C201:12FF:FE0C:0/Serial0/0 [3 paths]

Note: RIPng uses the link local IPv6 address as the next-hop IP address.
(Reminder: link local addresses begin with FE80.)

Note: To discover which routers use which link local addresses, and make it easier to work with link local addresses, you have a couple of options.
- First, you can set the MAC address of each LAN interface to something noticeable.
- Alternatively, you can just configure the link local address with the ipv6 address command, using the link-local keyword at the end, and make each link local address be more recognizable.

Note: To find the router whose link local address is listed in the IPv6 routing table, the show cdp entry name command can be useful because it lists both the IPv4 and IPv6 addresses, including the neighbor’s link local address.