Overview

RIPng troubleshooting is easier than in RIPv1 and v2. There are:

  • No classful networks
  • No summarization issues
  • No passive interface option
  • No RIP version issues
  • RIPng uses the authentication built into IPv6.

RIPng issues include:

  • Interface administratively shutdown on either side of the link
  • Interface’s IP address is in different subnet than its neighbor
  • Interface not participating in RIPng process
  • Another active protocol with a lower Administrative Distance than RIPng’s is inserted into routing table
  • Source and destination too many hops away from each other (15 hop maximum)
  • Maximum paths value
  • Maximum load balancing paths value
  • Filtering (routes or RIP packets)
  • Timer issues

Verification Commands

Let's take a look at useful commands for troubleshooting RIPng:

ping [node address]
traceroute [node address]

show ipv6 route [network/prefix]
show ipv6 route rip
show ipv6 route

show ipv6 protocols
show ipv6 rip
show ipv6 rip database

debug ipv6 rip - Careful using debug commands in a production networks - can be CPU and bandwidth intensive!
debug ipv6 [interface]

show ipv6 interface [interface ID]
show run interface [interface ID]

These commands not only vary in what information they show, but how much information they show. For example, it may be easier to issue a show command for only RIPng routes rather than the entire routing table.

Deciding which command to use and which order to use them may differ between administrators. Some administrators may prefer an ISO approach that's top-down, bottom-up or split-half. It's similar to how different chefs may make the "same" omelette a little differently.

Troubleshooting is an art...as well as a science!

Let's review some of the more common RIPng verification commands and their output:

show ipv6 protocols

The show ipv6 protocols command show all of the ipv6 routing protocol processes running on the router and specifies the participating interfaces for each of these processes. In this lab, only RIPng is running:

R-1#show ipv6 protocols  
IPv6 Routing Protocol is "connected" 
IPv6 Routing Protocol is "application" 
IPv6 Routing Protocol is "ND" 
IPv6 Routing Protocol is "rip RIP_TEST" 
 Interfaces: 
   GigabitEthernet0/1 
   GigabitEthernet0/0 
   Loopback16 
 Redistribution: 
   None

Line 5 shows the RIPng process and lines 6-9 list the participating interfaces.

show ipv6 rip

The show ipv6 rip command shows the RIPng process(es) running on the router with the participating interfaces. It also shows the port number, AD, timer values and more:

R-1#show ipv6 rip 
RIP process "RIP_TEST", port 521, multicast-group FF02::9, pid 370 
    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 10, trigger updates 1 
    Full Advertisement 2, Delayed Events 0 
 Interfaces: 
   GigabitEthernet0/1 
   GigabitEthernet0/0 
   Loopback16 
 Redistribution: 
   None

show ipv6 rip database

The show ipv6 rip database command shows all of the active RIPng processes and the routes learned from each process. It shows the metric, outgoing interface, link-local address on the remote router and how much time the route has before it will expire if it the timer isn't refreshed with an update from a remote router.

R-1#show ipv6 rip database 
RIP process "RIP_TEST", local RIB 
2001:12::/64, metric 2 
    GigabitEthernet0/0/FE80:12::2, expires in 151 secs 
2001:13::/64, metric 2 
    GigabitEthernet0/1/FE80:13::3, expires in 157 secs 
2001:23::/64, metric 2, installed 
    GigabitEthernet0/0/FE80:12::2, expires in 151 secs 
    GigabitEthernet0/1/FE80:13::3, expires in 157 secs 
2001:33::36/128, metric 2, installed 
    GigabitEthernet0/1/FE80:13::3, expires in 157 secs

Routes in the RIP database may or may not make it into the routing table. The routing table will only accept a route from this if it is the best path that the ipv6 routing table has to choose from. For example, if the same path is available via EIGRPv6 the EIGRPv6 route would be used since its AD=90 and RIP has an AD=120.

FYI: AD (Administrative Distance) is explained in the IPv6 Routing Table (RIB) lesson.

show ipv6 route rip

The show ipv6 route rip command shows a filtered ipv6 routing table with only RIPng routes:

R-1#show ipv6 route rip 
IPv6 Routing Table - default - 8 entries 
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route 
      B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP 
      H - NHRP, I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea 
      IS - ISIS summary, D - EIGRP, EX - EIGRP external, NM - NEMO 
      ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr - Redirect 
      RL - RPL, O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1 
      OE2 - OSPF ext 2, ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 
      la - LISP alt, lr - LISP site-registrations, ld - LISP dyn-eid 
      lA - LISP away, a - Application 
R   2001:23::/64 [120/2] 
    via FE80:13::3, GigabitEthernet0/1 
    via FE80:12::2, GigabitEthernet0/0 
R   2001:33::36/128 [120/2] 
    via FE80:13::3, GigabitEthernet0/1

I'll explain the output of more verification commands and techniques for troubleshooting in the next few lessons. In these lessons, we'll take a look at some RIPng troubleshooting tickets.

Cisco Press: RIP Next Generation (RIPng) - Verifying and Troubleshooting RIPng

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