Telecom Chapter 8 - TCP/IP Internetworking I

IPv4 Mask

32 bits long

Dual Stack

An IPv4-to-IPv6 transition method that runs both IPv4 and IPv6 on networking devices. Allows for IPv4 and IPv6 coexistence.

RST

An abrupt close uses a ________ segment. Used also when segment arrives that reciever isn't expecting.

IPv4 Protocol Field

In the header, describes messages in data field. 1 = ICMP 6 = TCP 17 = UDP

Acknowledgement Number Field

Indicates which segment is being acknowledged. TCP uses ACKs to achieve reliability.

IPv4

Which of the Internet Protocol version allows packet fragmentation?

Routing Decision

1) Find all row matches 2) Find the best-match rows 3) Send the frame out, based on information in the row

IPv4 and IPv6 Coexistence Tools

Dual Stack Tunneling Translation

simplify writing

IPv6 addresses help to ________.

Flag Fields

TCP has 9 single-bit fields called _____. Value of 1 means set, value of 0 means not set. Can be ACK, SYN, FIN, Urgent Pointer, PUSH, RST, or others.

row

In a routing table, a ________ represents a route for a group of IP addresses.

Reserved and Private IPv4 Addresses

10.0.0.0. - 10.255.255.255 172.16.0.0 - 172.31.255.255 192.168.0.0 - 192.168.255.255 169.254.0.0 - 169.254.255.255 240.0.0.0 - 254.255.255.255 127.0.0.0 - 127.0.0.255 local loopback

Sequence Number

32 bit field, TCP. TCP fragments long messages and this gives position so it can put them back together.

Urgent Pointer

A TCP header field that is used to identify higher-priority data that is interrupting a lower-priority transmission.

PUSH

A TCP header field that prioritizes a segment at the beginning of communications.

Border Router

A border router

TCP Reset Segment (RST)

A flag bit set that is sent when either side wishes to end a conversation on an abrupt close. A reset may occur if a problem is encountered during a connection, for security reasons, or for several other reasons.

Prefix Notation

A mask is represented by a slash followed by the number of initial 1s in the mask.

Interface

A router port

1

A router will discard a packet if the Time to Live (TTL) value in an arriving packet is ________.

Host Part

A term used to describe the last part of an IPv4 address that is used to uniquely identify a host inside a subnet.

Time to Live (TTL)

An IP field that assigns a value by source host. Different OS's have different ______ defaults. A router decrementing the _____ to 0 will discard the packet.

network part

In a network mask, the 1s correspond to the ________.

Routing Table

Each router has a ______ that it uses to make routing decisions. These have rows. Each row represents a route for a range of IP addresses-often packets going to the same network or subnet mask

physical layer

Ethernet standards are set at the ________.

Differentiated Services Control Point

Field that can be used for priority or other quality of service purposes. Can govern transmission quality. In the first row of an IPv4 packet.

Explicit Congestion Notification (ECN)

Field that can be used to reduce the transmission frequency between a pair of hosts to cope with congestion in the transmission system between them. In the first row of an IPv4 packet.

IPv6 Address Syntax

Global Routing Prefix (IPv4 network part) identifies the network in the internet. Subnet ID (IPv4 subnet part) identifies the subnet in the network. Interface ID - always 64 bits (IPv4 host part) identifies the host.

IPv4

Hierarchical, consisting of three parts (groups of bits) that locate a host in progressively smaller parts of the Internet. 1) Network Part 2) Subnet Part 3) Host Part

IPv6 Main Header

IPv6 packets can have multiple extension headers before the Data Field. IPv4 addresses = 32 bits. IPv6 addresses = 128 bits.

Payload Length Field

IPv6. Gives length of the packet payload, which is everything beyond the 40-octet main packet header. It includes both extension headers and the data field.

Hop Limit Field

IPv6. Is like the IPv4 time to live field. Each router along the way decrements the field's value by one, and if a router decrements it to zero, the router discards the packet.

the total length

If you see an IPv4 address, what do you know for certain?

ECN

In IPv4, the ________ field is used to deal with congestion in the Internet.

lower case

In IPv6 address simplification, text characters are expressed in ________.

both 4 symbols and 16 bits

In IPv6 addresses before simplification, there are ________ in a field.

Subnet Part

Most organizations further divide their networks into smaller units called _________. This specifies a particular subnet within the network.

No Header Checksum

Not in IPv6 because when IPv4 was created, there was a concern that if packet headers contained errors, they could cause serious problems for the Internet. Experience proved this concern to be groundless.

Recognized Organization

On the internet, "network" does not mean a single network such as an Ethernet LAN. It is an organizational concept. It means the routers and switches owned by a ___________, which is an end-user organization (Amazon.com and UofH) or an ISP.

Internal Router

Only connects different subnets within a network.

IP Protocol Field

Reveals contents of the Data Field. TCP and UTP have protocol values 6 and 17 respectively.

Find All Row Matches

Step 1 of the Routing Decision Router looks at the destination IP address in an arriving packet. Apply row's mask to the destination IP address in the packet. Compare the result with the row's destination value. If the two match, the row is a match.

Find the Best-Match Row

Step 2 of the Routing Decision The router examines the matching rows it found in Step 1 to find the best match row. Selects row with longest match (initial 1s in the row mask). The router now knows the best-match row.

Send the Packet Back Out

Step 3 of the Routing Decision Send the packet out the interface (router port) designated in the best-match row. If the address says Local, the destination host is on that interface. Sends the packet to the destination IP address in a frame.

Quality of Service (QoS)

The diffserv field in IPv4 is for ________.

Version Number Field

The first four bits in a packet to tell if it's an IPv4 or IPv6 packet. IPv4 = 0100 and IPv6 = 0110

default risk

The next-hop router listed in the last row is the ________ router.

Network Part

The portion of an IPv4 address that is either 1, 2, or 3 octets/bytes long (8, 16, or 24 bits long). Identifies the host's recognized network on the Internet.

Packet Fragmentation and Header Checksum

The two aspects that are gone in IPv6 that were present in IPv4. Not needed b/c IPv6 is very reliable.

Translation

Uses IP service that translates versions in cloud. Allows for IPv4 and IPv6 coexistence.

Routing

When routers forward incoming packets closer to their destination hosts

IPv6

Which has a better system for handling options beyond the main header?

Tunneling

Wraps IPv6 in IPv4 packet. Allows for IPv4 and IPv6 coexistence.

Hop-by-hop options

________ are the only extension headers that all routers must consider.