Path MTU for IPv4 and IPv6
In IPv4, path MTU discovery enables a host to actively identify and adapt to variations in the MTU size across different links along a data path. In contrast, IPv6 adopts an approach where fragmentation is managed by the packet's source when the path MTU of a specific link along the data path cannot accommodate the packet's size. This approach, where IPv6 hosts handle packet fragmentation, conserves processing resources in IPv6 devices and enhances the overall efficiency of IPv6 networks.
Topology
Figure 8-69: Path MTU Topology
R1
OcNOS#configure terminal | Enter configuration mode. |
OcNOS(config)#interface cd31/1 | Entering in to interface |
OcNOS(config-if)#mtu 1500 | Configure mtu |
OcNOS(config-if)#ip address 12.12.12.1/24 | Configure ipv4 address |
OcNOS(config-if)#ipv6 address 1001::1/64 | Configure ipv6 address |
OcNOS(config)#router ospf 1 | Configure ip ospf |
OcNOS(config-router)#ospf router-id 20.20.20.1 | Configure router id under ospf |
OcNOS(config-router)#network 12.12.12.0/24 area 0.0.0.0 | Add network under ospf |
OcNOS(config)#router ipv6 ospf 1 | Configure ipv6 ospf |
OcNOS(config-router)#router-id 1.1.1.1 | Configure router id under ospf |
OcNOS(config-router)#commit | Commit all the transactions |
OcNOS(config)#exit | Exit |
R2
OcNOS#configure terminal | Enter configuration mode. |
OcNOS(config)#interface cd31/1 | Entering in to interface |
OcNOS(config-if)#mtu 1500 | Configure mtu |
OcNOS(config-if)#ip address 12.12.12.1/24 | Configure ipv4 address |
OcNOS(config-if)#ipv6 address 1001::1/64 | Configure ipv6 address |
OcNOS(config)#router ospf 1 | Configure ip ospf |
OcNOS(config-router)#ospf router-id 20.20.20.1 | Configure router id under ospf |
OcNOS(config-router)#network 12.12.12.0/24 area 0.0.0.0 | Add network under ospf |
OcNOS(config)#router ipv6 ospf 1 | Configure ipv6 ospf |
OcNOS(config-router)#router-id 1.1.1.1 | Configure router id under ospf |
OcNOS(config-router)#commit | Commit all the transactions |
OcNOS(config)#exit | Exit |
Validation
OcNOS#sh in
installers interface
OcNOS#sh interface cd31/1
Interface cd31/1
Flexport: Non Control Port (Active)
Hardware is ETH Current HW addr: e49d.7356.df24
Physical:e49d.7356.df24 Logical:(not set)
Forward Error Correction (FEC) configured is Auto (default)
FEC status is N/A
Port Mode is Router
Protected Mode is Promiscuous
Interface index: 10142
Metric 1 mtu 1700 duplex-full link-speed 10g
Debounce timer: disable
ARP ageing timeout 1500
<UP,BROADCAST,RUNNING,MULTICAST>
VRF Binding: Not bound
DHCP client is disabled.
Last Flapped: Never
Statistics last cleared: 2023 Apr 03 17:24:58 (18:36:43 ago)
inet6 fe80::e69d:73ff:fe56:df24/64
ND router advertisements are sent approximately every 411 seconds
ND next router advertisement due in 176 seconds.
ND router advertisements live for 1800 seconds
Hosts use stateless autoconfig for addresses.
5 minute input rate 3 bits/sec, 0 packets/sec
5 minute output rate 1 bits/sec, 0 packets/sec
RX
unicast packets 0 multicast packets 180 broadcast packets 0
input packets 180 bytes 15000
jumbo packets 0
undersize 0 oversize 0 CRC 0 fragments 0 jabbers 0
input error 0
input with dribble 0 input discard 0
Rx pause 0
TX
unicast packets 0 multicast packets 176 broadcast packets 0
output packets 176 bytes 14632
jumbo packets 0
output errors 0 collision 0 deferred 0 late collision 0
output discard 0
Tx pause 0
Last modified date: 10/16/2023