Translation

English
label
0/100 · 5
English Czech Actions
Fragmenting packets on a per-link basis, as presented for the second solution, can minimize the transmission overhead since a packet is only fragmented on the links where fragmentation is required. Large packets can continue to be used downstream of a link that only accepts small packets. However, this reduction of the overhead comes with two drawbacks. First, fragmenting packets, potentially on all links, increases the processing time and the buffer requirements on the routers. Second, this solution leads to a longer end-to-end delay since the downstream router has to reassemble all the packet fragments before forwarding the packet.
The last solution is a compromise between the two others. Routers need to perform fragmentation but they do not need to reassemble packet fragments. Only the hosts need to have buffers to reassemble the received fragments. This solution has a lower end-to-end delay and requires fewer processing time and memory on the routers.
The first solution to the fragmentation problem presented above suggests the utilization of control packets to inform the source about the reception of a too long packet. This is only one of the functions that are performed by the control protocol in the network layer. Other functions include :
sending a control packet back to the source if a packet is received by a router that does not have a valid entry in its forwarding table
sending a control packet back to the source if a router detects that a packet is looping inside the network
verifying that packets can reach a given destination
We will discuss these functions in more details when we will describe the protocols that are used in the network layer of the TCP/IP protocol suite.
Virtual circuit organization
the outgoing interface for the packet
the label for the outgoing packet
For example, consider the `label forwarding table` of a network node below.
index
outgoing interface
label
0
South
7
1
none
2
West
3
East
If this node receives a packet with `label=2`, it forwards the packet on its `West` interface and sets the `label` of the outgoing packet to `2`. If the received packet's `label` is set to `3`, then the packet is forwarded over the `East` interface and the `label` of the outgoing packet is set to `2`. If a packet is received with a label field set to `1`, the packet is discarded since the corresponding `label forwarding table` entry is invalid.
`Label switching` enables a full control over the path followed by packets inside the network. Consider the network below and assume that we want to use two virtual circuits : `R1->R3->R4->R2->R5` and `R2->R1->R3->R4->R5`.
->R2
->R5
Since a packet received with `label=1` must be forwarded to `R5` with `label=1`, `R2`'s `label forwarding table` could contain :

Loading…

User avatar None

New source string

cnp3-ebook / principles/network — Czech

New source string 5 years ago
Browse all component changes

Glossary

English Czech
No related strings found in the glossary.

String information

Source string location
../../principles/network.rst:369 • ../../principles/network.rst:410 • ../../principles/network.rst:420 • ../../principles/network.rst:430 • ../../principles/network.rst:440
String age
5 years ago
Source string age
5 years ago
Translation file
locale/cs/LC_MESSAGES/principles/network.po, string 91