ccna 200 301 official cert g

ccna 200 301 official cert g.First, let's set aside OSPF for a moment and consider the MTU size. The MTU size is a setting for both IPv4 and IPv6 Layer 3 protocols. For now, we will consider only IPv6. the IPv6 MTU size of an interface will define the maximum bytes of IPv6 packets that the interface can forward. The same concept applies to both IPv4 and IPv4 MTUOTip: In IPv4, if an IPv4 packet exceeds the MTU of the interface, the router can split it into smaller packets. In IPv6, the host can check366 Chapter 17 Implementing IPv6 OSPF to detect the minimum MTU in end-to-end routing and avoid sending packets that exceed the MTU.The default value for most router interfaces is 1500 bytes for both IPv4 and IPv6 MTU. you can change these values for IPv4 and IPv6 using the ipmtusize and ipv6mtusizeinterface subcommands, respectively.We now move on to OSPFv3 and the fact that two routers become neighbors but cannot exchange their LSDBs because of different MTU settings. in particular. the neighbors learn from each other through Hello to reach a 2-way state and then enter a quasi-start state when the database exchange process begins. However, the database exchange fails because of the MTU mismatch, and the neighbor relationship ends by entering the down state.Example 17-12 gives an example of a special failure on R4. The example first changes the G0/0IPv6MTU of R4 to 1400, and then resets the OSPFv3 process. Example 17-12 LSDB Exchange Failure Caused by Mismatched IPv6 MTUR4# configure terminal Enter configuration commands, one per line. end with CNTL/Z. r4(config)# interface gigabitethernetO/O R4(config-if)# ipv6 mtu 1400 R4(config-if)# .Z R4#R4#clearipv6 osp f4process ResetOSPF process?[no]: yes R4#Jan 1723:53:24.439: %OSPFv3-5-ADJCHG:Process4, Nbr 1.1.1.1 on GigabitEthernetO/O from FULL to DOWN, Neighbor Down: Interface down or detachedR4#show ipv6 ospf neighbor