MTU value in EOS interop with Cisco XR

Summary:

• Arista mtu value under interface is IP MTU value, while Cisco XR's mtu is L2 MTU
• So when ISIS peering fails to come up if both sides have same MTU value
• XR's mtu = EOS's mtu + 14 (Ethernet header length)

https://eos.arista.com/forum/isis-between-arista-and-ios-xr/