BROCADE IP PRIMER

Chapter 1: Networking BasicsAs you can see, the sender sends three segments and waits for the acknowledgmentfrom the receiver. The receiver sends the acknowledgment. Now, thesender can send three more segments, and so on.Connection-oriented transport also uses something called flow control. Theidea here is that the sender wants to make sure he's not overwhelming thereceiver with information. Let's say you have a super-fast server that needs tosend information to a 15-year-old workstation (don't think this won't come up).The workstation probably doesn't have that fast a network connection, and itsprocessor won't be able to handle information nearly as quickly as the server.This is where the Transport Layer comes to the rescue.SourceDestinationSegmentSegmentSegmentPAUSE“Woah! Wait a minute!I gotta catch up!”RESUMESegment“Okay, go ahead!”SegmentSegmentThe receiver is able to send a message back to the sender saying, “Whoa! Waita minute! Let me catch up! Okay, now I'm ready. Go ahead.” This is one moremechanism that connection-oriented transporting uses to make sure that thedata arrives reliably.One other mechanism used by connection-oriented transporting is labeling thesegment with an order number. Seems simple, doesn't it? It breaks up thedata into segments, but it's careful to label each segment (“This is the firstsegment...this is the second segment...”, etc.). Why would it need to do this?Well, it's always possible that something may happen on the way to thereceiver that may put the segments out of order. If that happens, the receiver'sTransport Layer will simply look at the segment labels and reassemble them inthe correct order.But what if a segment is missing? How will the receiver know? There will be abreak in the order. The receiver will be reassembling the segments, and maynotice, “Hey, I've got segment 1, 2, 3, 4, 5, and 7, but I don't have 6." At this14 Brocade IP Primer