IPv6: IPv6 Routing + OSPF v3

IPv6 Routing

To go along with the new address types, we have new variations of:

  • RIP for IPv6 – the actual name is RIPng (new generation)
  • EIGRP for IPv6
  • ISIS for IPv6
  • OSPF v3 (Version 3, defined in RFC 2740.)
  • Static routes are still available with IPv6
  • Multiprotocol BGP V4 (MPBGPVer4 or simply MPBGP)

We need to enable a Cisco router’s IPv6 routing capabilities with ipv6 unicast-routing.

R1(config)#ipv6 unicast-routing

OSPF for IPv6 (OSPF v3)

During an IPv4 to IPv6 migration, you may run OSPF v2 and OSPF v3 side by side.

In IPv6, you’re not going to start an OSPF configuration with router ospf. One major difference between v2 and v3 is that v2 is enabled in router config mode and v3 is enabled on a per-interface basis.

This will automatically create a routing process.

R1(config-if)#ipv6 ospf 1 area 0

OSPF v3 is going to use the exact same set of rules to determine the local router’s RID – and v3 is going to use an IPv4 address as the RID

OSPFv2 and V3 differences

  • The basic operational theory of v3 is very similar to that of v2. The Hello packet is still around, as are the LSAs and LSAcks.
  • Stub, total stub, and NSSAs are still around, and the Area 0 rule still exists (as do virtual links).
  • The general rules for neighbor discovery and adjacencies are the same.
  • v3 NBMA configurations require neighbor statements, just like v2.
  • One major difference between the two is that v3 allows a link to be part of multiple OSPF instances, where v2 would allow a link to be part of only one.
  • v3 point-to-point and point-to-multipoint configurations do not elect DRs and BDRs, just like v2.
  • v3 headers are smaller than v2, since v3 headers have no authentication fields.
  • The v2 reserved address is represented in v3 by FF02::5.
  • The v2 reserved address is represented in v3 by FF02::6.
  • We can still use the area range command, and IPv6 does make summarisation more effective – but when you use the area range command in v3, the OSPF cost of that summary is simply the highest of the individual route costs.

Author: drbabbers

ccieme.wordpress.com - my personal journey to ccie