CSE 123 Lecture Notes - Lecture 10: Internet Control Message Protocol, Future Proof, Loopback

• School: UCSD
• Department: Computer Science and Engineering
• Course: CSE 123
• Professor: Alex Snoeren

Document Summary

But the router will keep dropping this packet! Router detects a problem with the packet! If the router drops the packet, the sender will resend it! Need to explicitly let the sender know that you cannot send this packet! Ip header will not be used (instead will use a icmp header!) Ttl expired (exploded in the router"s hands!) Icmp messages include portion of ip packet that triggered the error (if applicable) in their payload. You never generate icmp in response to icmp! I. e you don"t get to whine back! Fragments (if the error is caused by the host, then it"s the first fragment!) Ip header that is corrupt or has bogus source! Icmp messages are often rate-limited too! (less bandwidth) Why not choose an arbitrarily long address? waste space on the header! 32-bits on ipv4 ( < 1 address per person!) In korea, they have 4 ip addresses per person!