Why is IPsec transport mode "vulnerable" for not having integrity of variable fields? Why is this so important?

With IPsec transport mode we CAN’T have integrity of variable fields (eg TTL and checksum).
Why is it a problem? Is it? What could be the attack?
I think TTL expire or checksum modification (so both DoS), but I mean, if an attacker can mod… Continue reading Why is IPsec transport mode "vulnerable" for not having integrity of variable fields? Why is this so important?