medium
Single Answer
0What is the default MTU of a GRE tunnel?
Answer Options
A
MTU 1476
B
MTU 1492
C
MTU 1500
D
MTU 1528
Correct Answer: A
Explanation
The maximum transmission unit of a GRE tunnel is 1476 because there are 24 bytes of overhead for the GRE header; 20 bytes are used by the public IP header and 4 bytes are used for GRE. Ethernet is commonly set to an MTU of 1492 or an MTU of 1500. An 802.1Q packet is commonly set to an MTU of 1528 because of the additional VLAN tagging information.
gre
mtu
tunneling