New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

Class Note for COSC 6397 at UH


Class Note for COSC 6397 at UH

Marketplace > University of Houston > Class Note for COSC 6397 at UH

No professor available

Almost Ready


These notes were just uploaded, and will be ready to view shortly.

Purchase these notes here, or revisit this page.

Either way, we'll remind you when they're ready :)

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

No professor available
Class Notes
25 ?




Popular in Course

Popular in Department

This 33 page Class Notes was uploaded by an elite notetaker on Friday February 6, 2015. The Class Notes belongs to a course at University of Houston taught by a professor in Fall. Since its upload, it has received 20 views.

Similar to Course at UH


Reviews for Class Note for COSC 6397 at UH


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 02/06/15
39 Ii Summary of Mobile IP Operations I Careof address to identify a host s point of attachment I Correspondent node CN gt mobile host MH 1 1 Use of MH s permanent IP address as destination address Intercepted by MH s home agent encapsulated in an lPinIP packet Decapulated at FA or a MH itself I MH gt CN Use its permanent IP address as source address Send directly to ON using IP fonNarding Reverse tunneling is optional 204 39 I Message Format in Mobile IP I Agent advertisement ti Type 16 l l Seq no count of Agent Advertisement messages sent since the agent was initialized in Life time the longest lifetime measured in seconds that this agent is willing to accept in any Registration Request 0 l 2 3 O l 2 3 4 5 6 7 8 9 O l 2 3 4 5 6 7 8 9 O l 2 3 4 5 6 7 8 9 O l Type Length Sequence Number Registration Lifetime RBHFiMiGV reserved zero or more Care of Addresses 205 39 1 quot Registration Request I Type 1 I Identification A 64bit number constructed by the mobile node used for matching Registration Requests with Registration Replies and for protecting against replay attacks of registration messages l i l l l i l 0 l 2 3 0 l 2 3 4 5 6 7 8 9 0 l 2 3 4 5 6 7 8 9 0 l 2 3 4 5 6 7 8 9 O l eeeeeeeeeeeeeeee77eeeeeeeee eeee Type e e eeeeere eeeeeee sBlDlMGvrsv Lifetime eA e e Extensions r Home Address eeeeeeeeereeeeeere Home Agent Careeof Address Identification eeeeeeeeeeeeeeeee e4 eree eeeee 206 ill 39 1 U Registration Reply I Type 3 I Code a value for the result of request 0 O l 2 3 4 5 6 7 8 9 0 l 2 3 4 5 6 7 8 9 0 l 2 3 4 5 6 7 8 9 O l Type Code Lifetime Home Address Home Agent Extensions Identification 207 39 1 Mobility in IPv6 I Route Optimization is a fundamental part of Mobile IPv6 1 1 In Mobile IPv4 it is an optional set of extensions that may not be supported by all nodes I Foreign Agents are not needed in Mobile IPv6 IPv6 supports stateless address auto configuration and neighbor discovery MNs can function in any location without the services of any special router in that location I Security Nodes are expected to employ strong authentication and encryption 208 Transport Issues 209 39 Ii Scope revisited Personal Area Networks Sensor Networks Mobile ServiceApp Routing Medium Access Control lueuie euew nonuoo Jemod SOC Munoes Physical Layer 210 39 I Transport Protocols in the Internet I UDP user datagram protocol 1 Application level endtoend connection l l Unreliable datagram delivery 2 Applications DHCP DNS SNMPNFS I TCP transport control protocol l l Connection oriented reliable byte stream 1 Congestion control amp flow control 1 l HTTP telnet 211 39 L Why Do We Worry about Transport Layer I If Mobile IP claims to provide mobility transparency G 1 M 00 e quot i TCP UDP MIP Link Layer NIC Mobility transparency in routing is not enough 212 Factors that Affect TCP Performance I Wireless channel 1 Error rate 1e6 Dynamic link quality Mobility 1 Out of order delivery 1 Longer round trip time RTT Disconnection 31 1 3 RTT 2bp 01xI7 Client 5 Y Ser39ver39 nISN Connection Setup 3way handshake 213 39 I L39 Window Based Flow Control I Sliding window protocol I Window size minimum of iZl receiver s advertised window determined by available buffer space at the receiver Ll congestion window determined by the sender based on feedback from the network Sender s window E 4 5 6 7 8 940311 lt Acks received gt Not transmitted 214 IF indow Based Flow Control Sender s window ACk 5 Sender s window 215 39 I quot Ack Clocking I Chen Server I TCP window flow control is self clocking I New data sent when old data is ack d I Ack is cumulative I Indication of losses 216 39 1 L39 How does TCP detect a packet loss I Retransmission timeout RTO I Duplicate acknowledgements 217 USing Retransmission Timeout RTCCID s i 1 er39ver39 I At any time TCP sender sets retransmission timer for only one packet I If acknowledgement for the timed packet is not received before timer goes off the packet is RTC assumed to be lost I RTO dynamically calculated 218 39 I quot Retransmission Timeout RTO calculation I RTO mean 4 x mean deviation srtt 05 RTT 1a srttn n1 rttvarn1 B RTT srttn 1 8 rttvarn RTO srtt 4 rttvar n1 n1 n1 I Large variations in the RTT increase the deviation leading to larger RTO I RTO backoff exponentially after each timeout RTOn1 max 2 RTOn 64 seconds 219 Ltoss Using Dupacks and Fast Retransmit Mechanism I Dupacks may be generated due to packet loss or outof order packet delivery I TCP sender assumes that a packet loss has occurred if it receives three dupacks consecutively 3 dupacks are also generated if a packet is delivered at least 3 places beyond its insequence location almostordered w 5 unnecessary 220 ill 39 I Congestion Control in TOP 25 After timeout 20 20 ssthresh 10 ssth resh 8 Congestion window segments O 01 O 01 I I I osoog 3 m Time round trips 221 39 1i Hand ing Wireless Errors MH I Problem D In TCP Packet Loss gt Congestion gt TCP reduces sending rate i i But in Mobile Networks packet loss can be caused by disconnections handoffs high bit error rates t 1 Solution hide wireless errors from TCP sender Retransmissions at base stations Notification to TOP sender modification at end hosts 222 11 11 Snoop I lmprovinq TCPIP Performance over Wireless Networks Mobicom 95 Hari Balakrishnan Srinivasan Seshan Elan Amir Randy H Katz I Key idea li Data from CN gt MH Cache unacknowledged TCP data Perform local retransmissions li Data from MH gt BS Detect missing packets Perform negative acknowledgements 223 39 I Snoop Protocol I Per TCPconnection state TCP connection application transport network link physical application transport network A rxmt link Ill 4 physical application A transport network link physical wireless 224 39 1 Snoop MHgt BS I New pkt can be used to estimate RTT on 1 Forward packet Wireless 2 Reset local rexmit I Outofseq cached counter earlier it 1 If ack ed by MH retransmit an ACK 1 7 Else forward to MH Packet arrives Sender rexmission 1 Mark as cong loss 2 Forward pkt ln sequence Congestion loss 1 Cache packet 2 Forward to mobile Common case 225 39 I quot ACK from MH III I Spurious ACK 1 Free buffers neither new or dup 2 Update RTT estimate 3Propagate I Dupack ack to sender Common case 1 Not in cache or marked restranmission route dupack to ON quot If in cache rst one Retransmit lost retransmit packet with high priority Ack arrives Discard toi iz si g QSSf Next pkt lost I Retransmission from BS based on timeout 226 39 I quot Data Transfer from MH gt FH I MH timeouts for packets lost in first link will happen much later than they should I NACKs sent from BS to MH when 1 l Threshold no of packets from a single window have reached 1 No new packets from MH for certain time Based on TCP SACK 227 39 1 L39 Performance I Error rate 39x106 I Snoop 1MbpsTCP 025 Mbps 12907 Snoop Regular TCP vr39 5 1 e07 a 8906 Se06 Sequence number 4e06 2606 100 150 200 250 300 350 Time seconds 228 39 1 quot Handling Mobility An End Host Approach I Benefits of End Host Solutions 3 No triangle routing l l No change in the IP substrate Cl TCP peer can suspend an open connection and reactivate it from another IP address transparent to an application that expects uninterrupted reliable communication with the peer I An EndtoEnd Approach to Host Mobility Alex C Snoeren and Hari Balakrishnan the sixth ACM MobiCom 2000 229 39 L39 Migrate Architecture Location Update Dynamic DNS Update DNS Server Connection Migration Correspondent quotU Host Mobile Host 00 bar edu yWWyWyyyy xxx 230 39 I Implementation in TCP I Provide special Migrate option 1 Sent on SYN packets of new connection l l Indicates new connection should be joined to a previous one I Use previous sequence space 1 Works with SACK FACK Snoop I Preserve threeway SYN handshake 1 l Works with statefull firewalls 231 xed xmwszy 5115mm ImgmLcOk Km ummmmp Tm SYN owzmxsszuoy xck 531522 migmltDk m umcsmmp m wk 1231522 TCP Connection Migration 1 InitiaISYN i i 2 SYNACK 3 ACKWith data TCP Connection Migration mobile XEd 54501545957636 4 ad mm 4 Normal data transfer TCP Connection Migration mobile XEd 3 1092197 Imam mm 1 R I 5 M lg rate SYN 968 Mlgrate 7 ACK With data CLOSED TCP State send nothing h a I O 1 quot LISTEN senilezcsv il CK SWeSENT 2 new transitions between existing states and 1 new state handes pathological race condition recv SYN migrate T R send SYN ACK MIGRATEJNAIT 2MSL tnneout Q Migration Trace 36533 I I I I I I E Era 8438 4 BE a M m a SIN Am 3 E m 5 82686 6 E A o J E m I A 9 E I 3 o E I w seam o a II I E 9 I a v o a s o g E 3 I3 I a 78686 3 z III lt gt g Buffered 3 7saaa c g 93 Packets 9 3 old address 74662 a o o I b 9 3 a a G quot new 9 Ingmar 3 39 H Before Data 0quot QCKS w quot After Data a Hm I 73982 I I I I I I a e 4 5 3 1a 12 Time secs 236


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Steve Martinelli UC Los Angeles

"There's no way I would have passed my Organic Chemistry class this semester without the notes and study guides I got from StudySoup."

Kyle Maynard Purdue

"When you're taking detailed notes and trying to help everyone else out in the class, it really helps you learn and understand the I made $280 on my first study guide!"

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"


"Their 'Elite Notetakers' are making over $1,200/month in sales by creating high quality content that helps their classmates in a time of need."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.