outstanding segments = the segments that are sent and still not acknowledged
Base: the sequence number of the oldest unacknowledged packet
NextSeqNum: the sequence number of the first next packet to be sent
N: the size of the window
the receiver must deliver in-order bytes of data to the upper layer protocol
In GBN protocol,
out-of-order received segments are discarded. If the receiver expects a byte with SeqNum, but receives a byte with SeqNum + 1, it sends an ACK for byte SeqNum and discards the SeqNum+1 byte because it will be considered out of order. In other words, the receiver sends an ACK for each received in-order segment.
at the sender side, if the application layer gives data to the Transport layer whose sequence number is larger than base + N, TCP signals to the application that it rejected the data because the window is full.
Sender maintains only one timer. The timer starts with the oldest-sent-yet-not-acknowledged segment. With each ACK received, the Sender checks if there still are segments that are sent and not acknowledged. If so, the timer restarts. However, if there are no sent-yet-unacknowledged segments, the timer stops
if ACK for segment k is not received, then a timeout occurs and the sender retransmits all the segments up to the last sent-yet-not-acknowledged segment. For example, if the sender already sent segment 2 up to 5, and ACK 2 is not received, then in Go Back N the sender retransmits segments 2, 3, 4 and 5.
The following diagram describes the operations of the Go Back N protocol.
Call forwarding is one of the features of the call coverage in Cisco CUCM. Call Hunting is when CUCM distributes a call on more than one Directory Number (DN), whether consecutively or simultaneously, depending on the algorithm. Hunt Pilot A Hunt Pilot is the entry point for the whole call hunting process. It is hit by a Call. The Hunt Pilot number is a dialable entity and has many similarities with Route Patterns : We can configure Route Filters with Hunt Pilots, Hunt Pilots can Provide Outside Dial Tone , We can set Hunt Pilots with the Urgent Priority flag, They can route or block calls, They can apply Calling and Called Party Transformations. Hunt Lists After hitting the Hunt Pilot, the call is presented by CUCM to the Hunt List. Each Hunt List contains one or more ordered Line Groups. A Hunt List can be pointed by one or more Hunt Pilots. Line Groups Each Line Group contains one or more member (we’ll refer to them as Hunt members, hunt parties or Line Group members). A Line Grou...
In this post, we will understand the nuances between the following concepts related to ISDN PRI: TDM links and interfaces T1, T1 PRI, E1, E1 PRI, ISDN BRI ISDN E1 PRI and ISDN T1 PRI E1 and T1 are two TDM technologies; they leverage Time Division Multiplexing to transmit and receive information. E1 TDM link provides a total 2.048 Mbps bandwidth. T1 TDM link provides a total 1.544 Mbps bandwidth. Both the E1 TDM and the T1 TDM links are segmented into channels, or timeslots. Each timeslot allows a bandwidth of 64 kbps. E1 TDM and T1 TDM have been used in the past to carry digitized voice. But since carrying voice and data is the same thing -from a transmission perspective- then T1 TDM and E1 TDM have been leveraged to carry data, voice and even video. E1 TDM, T1 TDM and WAN Protocols E1 TDM and T1 TDM can be used to carry PPP traffic. Also, E1 TDM and T1 TDM are used as a Link Layer transport protocol for ISDN PRI technology. That’s why we find in literature E1 PR...
Comments
Post a Comment