You have configured multiple IP-IP tunnels across your network to provide connectivity to remote sites. Which technique is used to help the IP endpoints in your network determine the optimal packet size to send across your tunnels?
Click on the arrows to vote for the correct answer
A. B. C. D.A
The correct answer is A. Path MTU discovery.
When IP packets traverse a network, they may encounter links with a smaller maximum transmission unit (MTU) than the size of the packet itself. In such cases, the packet must be fragmented, which can introduce additional overhead and potentially affect performance.
Path MTU discovery is a technique used to determine the minimum MTU along a path between two IP endpoints. By discovering the minimum MTU, IP endpoints can adjust the maximum size of the packets they send to avoid fragmentation.
In the context of IP-IP tunnels, path MTU discovery can help the endpoints in the network determine the optimal packet size to send across the tunnels. This is important because tunnels may have a smaller MTU than the underlying network, and sending packets larger than the tunnel's MTU can cause fragmentation and affect performance.
To perform path MTU discovery, the IP endpoint sends packets with the "don't fragment" (DF) bit set and progressively increases the packet size until it receives an ICMP "fragmentation needed" message from a router along the path. This message indicates the minimum MTU of the path, and the endpoint can then adjust its packet size accordingly.
In summary, path MTU discovery is a technique used to determine the minimum MTU along a path between two IP endpoints. It is used to avoid fragmentation and ensure optimal packet size when traversing networks with varying MTUs, including IP-IP tunnels.