10 Questions
What is the source IP address of the DHCP ACK message?
223.1.2.5
What is the lifetime of the IP address allocation in seconds?
3600
What is the purpose of the DHCP protocol?
To allocate IP addresses to clients
What is the IP address of the client after receiving the DHCP ACK message?
223.1.2.4
What is the purpose of the subnet mask in an IP address?
To determine the network ID of the client
How does an ISP allocate IP addresses to its customers?
By allocating a portion of its own IP address space to each customer
What is the advantage of hierarchical addressing in IP routing?
It allows for more efficient advertisement of routing information
What is the function of the first-hop router in an IP network?
To route packets between networks
What is the purpose of the DNS server in an IP network?
To resolve domain names to IP addresses
What is the format of the IP address allocated by the ISP to its customers?
IP address and subnet mask
Study Notes
IPv6 Datagram Format
- 27 fixed-length 40-byte header with no fragmentation allowed
- Priority: identifies priority among datagrams in a flow
- Next header: identifies upper layer protocol for data
- Ver: identifies the version of the IP protocol
- Pri: indicates the priority of the datagram
- Flow label: identifies a specific flow of datagrams
- Hop limit: specifies the number of hops the datagram can travel
- Payload length: specifies the length of the payload
- Next header: specifies the next header in the datagram
- Source address: 128-bit address of the source
- Destination address: 128-bit address of the destination
- Data: the actual payload of the datagram
Transition from IPv4 to IPv6
- Not all routers can be upgraded simultaneously
- No "flag days" for transition
- Tunneling: IPv6 datagram carried as payload in IPv4 datagram among IPv4 routers
- IPv4 header fields: IPv4 source and destination addresses
- IPv6 header fields: IPv6 source and destination addresses
- UDP/TCP payload: IPv6 datagram carried as payload in IPv4 datagram
Network Layer
- Interplay between routing and forwarding
- Routing algorithm determines end-end-path through network
- Routing algorithm determines local forwarding table
- Forwarding table determines local forwarding at this router
- Graph abstraction: represents network as a graph of nodes and edges
- Graph abstraction: costs associated with each link
ICMP
- Internet control message protocol
- Used by hosts and routers to communicate network-level information
- Network-layer "above" IP
- Error reporting: unreachable host, network, port, protocol
- Echo request/reply (used by ping)
- ICMP messages carried in IP datagrams
- ICMP message format: type, code, plus first 8 bytes of IP datagram causing error
Traceroute and ICMP
- Source sends series of UDP segments to destination
- First set has TTL = 1, second set has TTL = 2, etc.
- When nth set of datagrams arrives at nth router, router discards datagrams and sends source ICMP messages (type 11, code 0)
- ICMP messages include name of router and IP address
DHCP
- More than just IP addresses
- Can return address of first-hop router for client, name and IP address of DNS server, and network mask
- Address allocation: gets allocated portion of its provider ISP's address space
- Hierarchical addressing: allows efficient advertisement of routing information
Test your understanding of the IPv6 datagram format, including its header fields and priority, as well as the transition from IPv4 to IPv6. Learn about the key differences between the two protocols and how they impact network communication.
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