CSE555-SqalliTerm 0321-3-1 An Overview of Selected Protocols (Courtesy: Dr. Waheed) Channel access protocols Network layer level protocols Transport

Term 032 1-3-1 CSE555-Sqalli

An Overview of Selected Protocols(Courtesy: Dr. Waheed)

Channel access protocols Network layer level protocols Transport layer level protocols Application layer level protocols Recent work

Objective of this review: To help you select one protocol for your term project


Channel Access Protocols ALOHA Carrier sense multiple access (CSMA) protocols Collision-free protocols Limited contention protocols Channel access protocol standards

IEEE 802.x standards

All of these protocols deal with “channel access problem”

Allocation of a shared channel among multiple stations All of these protocols are implemented at medium

access sublayer level MAC layer is part of data link layer


Network Layer Level Protocols

IPv4 IPv6 Mobile IP RSVP Internet control protocols

ICMP ARP RARP

OSPF BGP


IP Protocol

Along with the Transmission Control Protocol (TCP), IP represents the heart of the Internet protocols

IP is a network-layer protocol that contains Addressing information and Some control information that enables packets to be

routed Documented in RFC 791 IP has two primary responsibilities:

Providing connectionless, best-effort delivery of datagrams through an internetwork; and

Providing fragmentation and reassembly of datagrams to support data links with different maximum-transmission unit (MTU) sizes

IP is a stateless protocol


RSVP: Resource Reservation Protocol

RSVP allows Multiple senders to transmit to multiple groups of receivers Individual receivers to switch channels (groups) freely Optimize BW use while eliminating congestion

RSVP uses multicast routing through spanning trees Each group is assigned a group address Sender puts group’s address in packets Routing algorithm builds a spanning tree of all members of

a group Difference from normal multicast:

Some extra information that is multicast to the group periodically to tell routers along the way to maintain certain data structures


Internet Control Message Protocol (ICMP) ICMP is used to report unusual events or to test the

internet Several types of ICMP messages

Destination unreachable Time exceeded Parameter problem Source quench: choke packet Redirect: teach the router about geography Echo request: ask a machine if it is alive Echo reply: yes, I’m alive Timestamp request: same as echo request but with

timestamp Timestamp reply: echo reply with timestamp

Each ICMP message type is encapsulated in an IP packet


Address Resolution Protocol (ARP) Data link layer hardware does not understand IP addresses Mostly hosts are connected through Ethernet LANs

All Ethernet cards have a unique 48-bit (data link layer) address How to map an IP address to data link address?

One solution: use of a configuration file Other solution: Address Resolution Protocol (ARP)

ARP: Host that needs to map IP address to Ethernet address broadcasts

a packet on the Ethernet, asking “Who owns IP address w.x.y.z?” Each machine on Ethernet receives this broadcast and checks its

IP address Machine with matching IP address will respond with its Ethernet

address to the sender Almost every machine on internet runs ARP

ARP is defined in RFC 826


Reverse ARP (RARP) ARP finds Ethernet address corresponding to an IP address Sometime reverse problem has to be solved: mapping an

Ethernet address to IP address This problem occurs while booting a diskless workstation, which

gets its OS binary image from a remote file server How does it learn its IP address?

This problem is solved by RARP A newly booted workstation broadcasts its 48-bit Ethernet address

and asks for corresponding IP address RARP server sees this request, looks up Ethernet address in its

configuration files, and sends back corresponding IP address RFC 903 Advantage: IP address is not needed in memory image Disadvantage: RARP uses broadcast to reach RARP server;

therefore, all networks are required to have one RARP server as it cannot go through routers

Solution: Use BOOTP


Bootstrap Protocol (BOOTP) It is a UDP/IP based protocol that allows a network user to

Automatically receive an IP address or Have a diskless workstation boot automatically by

Discovering its own IP address; Discovering the IP address of a server; and Obtain the name of a boot file that should be loaded into

memory It uses UDP messages that are forwarded over routers

Bootstrap process has two phases: IP address discovery and boot file selection phase (BOOTP) File transfer phase

BOOTP server managed by a network administrator automatically assigns the IP address form a pool of IP addresses

It is a basis for an advanced network manager protocol, Dynamic Host Configuration Protocol (DHCP)


Interior Gateway Routing Protocol: OSPF

Internet consists of autonomous systems (ASes) Each AS operated by a different organization Each AS can use any routing algorithm within its network Still standards help

Simplify boundary between ASes Reuse of code

A routing algorithm within an AS is called Interior Gateway Protocol

Open Shortest Path First (OSPF) routing algorithm Successor of link state routing algorithm, which was a

successor of Bellman-Ford distance vector routing algorithm

It became a standard in 1990 and many router vendors support it


Exterior Gateway Routing Protocol: BGP A routing algorithm between ASes is called an Exterior Gateway

protocol Border Gateway Protocol (BGP) is used for routing between ASes

Different from OSPF as routing goals are also different Gateway routers often need to enforce certain policies

Send and receive all packets to and from the Internet Do not carry transit packets from foreign ASes Carry transit traffic from specific ASes, etc. Example: traffic starting or ending at SUN should not transit Microsoft

Policies are manually configured into each BGP router BGP router handles transit traffic with three categories of

networks: Stub networks

Have one connection to BGP graph and cannot be used for transit Multiconnected networks

Have multiple connections but some may refuse transit traffic Transit networks

These are backbones willing to handle third-party packets


BGP (Cont’d)

Pairs of BGP routers communicated using TCP BGP is a distance vector protocol but differ from most

others, such as RIP Instead of maintaining just the cost to each destination,

each BGP router keeps track of the exact path used Instead of periodically providing distance info to each

neighbor, each BGP router provides exact paths it uses to all other routers


Transport Layer Level Protocols

TCP UDP AATM AAL protocols


TCP Protocol TCP entities exchange data in variable sized segments

Consists of 20-byte header with 32-bit seq. #, followed by data It can accumulate data from several writes or split data from one

write over multiple segments Two restrictions on the size of a TCP segment

Segment, including 20-byte header should fit in 65,535 byte IP payload Segment must fit in maximum transfer unit (MTU) of a network to

avoid fragmentation/reassembly Each fragment adds 20 byte segment header

Basic protocol used by TCP entities: sliding window protocol When sender transmits a segment, it also starts a timer After receiving segment, the receiver sends an ack segment with

an ack # that is equal to next sequence # it expects to receive If sender timesout before receiving ack, it retransmits the

segment


TCP Protocol (Cont’d)

TCP need to handle following problems Bits and pieces of delayed, duplicate segments that may

be fragmented differently Require special attention to extract the correct segments at

receiver Example: bytes 3072-4095 arrive but cannot be acknowledged

until 2048-3071 bytes are received Retransmitted segments can take different routes resulting

in different fragmentations TCP entity at receiving end is responsible for reliably

extracting the original segment even though sporadic delayed duplicate fragments may turn up

Segments may occasionally hit a congested network A number of algorithms have been implemented in TCP

to solve these problems


UDP

This is a connectionless protocol Encapsulated IP datagram Useful for applications that need one request and one

response A UDP segment consists of 8 byte header

UDP length includes 8 byte header and data UDP checksum is optional

0 if not computed 1’s complement of the sum of UDP header, data (padded to

even number of bytes), and pseudo header


ATM AAL Protocols

If ATM layer’s functionality is similar to network layer, AAL is similar to transport layer

AAL 5 protocol is similar to UDP

Four protocols to handle four classes of service AAL1 – AAL4

Requirements for classes C and D were so similar that AAL3 and AAL4 are combined into AAL ¾

AAL5 proposed by computer industry in contrast to telecommunication industry that proposed AAL1 – AAL3/4


Application Layer Level Protocols

Authentication protocols DNS SNMP E-mail related protocols NNTP HTTP Multimedia related protocols

RTP RTSP


Recent Protocols

Active IETF working groups in following areas: Applications Internet Operations and management Routing Security Sub-IP Transport


Applications Area Protocols

Cross Registry Information Service Protocol (CRISP) Instant Messaging and Presence Protocol (IMPP) Lightweight Directory Access Protocol (LDAP) Message Tracking Protocol (MsgTrk) SIP for Instant Messaging and Presence Leveraging

Extension (SIMPLE)


Internet Area

Dynamic Host Configuration Protocol (DHCP) Extensible Authentication Protocol (EAP) IP over Cable Data Network (IPCDN) IP over InfiniBand (IPoIB) IP Routing for Wireless/Mobile Hosts (MobileIP) Protocol for Carrying Authentication for Network Access

(PANA) IPv6


Operations and Management Area

IP Flow Information Export (IPFIX) Resource Allocation Protocol (RAP) Remote Network Monitoring (RMONMIB) Configuration Management with SNMP (SNMPConf) SNMP version 3 (SNMPv3)


Routing Area

Border Gateway Multicast Protocol (BGMP) Inter-Domain Multicast Routing (IDMR) Inter-Domain Routing (IDR) Multicast Source Discovery Protocol (MSDP) Routing Information Protocol (RIP) Virtual Router Redundancy Protocol (VRRP)


Security Area

Authenticated Firewall Traversal (AFT) IP Security Protocol (IPSec) Kerberized Internet Negotiation of Keys (KINK) Multicast Security (Msec) An Open Specification for Pretty Good Privacy

(OpenPGP) Public-Key Infrastructure (PKIX) Secure Network Time Protocol (STIME) Transport Layer Security (TLS)


Sub-IP Area

General Switch Management Protocol (GSMP) IP Over Optical (IPO) Multiprotocol Label Switching (MPLS) Provider Provisioned Virtual Networks (PPVPN)


Transport Area

Audio/Video Transport (AVT) Datagram Congestion Control Protocol (DCCP) Differentiated Services (DiffServ) Telephone Number Mapping (ENUM) IP Telephony (IPTel) Media Gateway Control (MEGACO) Multiparty Multimedia Session Control (MMUSIC) Network File System Version 4 (NFSv4) Robust Header Compression (ROHC) Session Initiation Protocol (SIP) Speech Services Control (SpeechSC)


Other References

http://www.iol.unh.edu/

http://www.ietf.org/rfc/rfcxx00.txt

Documents

CSE555-SqalliTerm 0321-3-1 An Overview of Selected Protocols (Courtesy: Dr. Waheed) Channel access protocols Network layer level protocols Transport