0
It's a time-to-live field designating that the packet is OK to forward from one device to another for a certain amount of time. If the packet gets caught in a routing loop, it won't just go back and forth forever. If that were allowed to happen, many other packets would be doing the same thing, just being mis-routed back and forth between the confused devices, until the available bandwidth on the link was saturated.
The TTL assures that the packet will not be forwarded by the very next routing device that reads the packet's TTL field and sees that its TTL has expired. The packet would be discarded at that point.
Wiki User
∙ 9y ago
Wiki User
∙ 12y agoThe TTL field is between 0-255, and the TTL is decremented one value for each hop (each router the IP packet traverses). This means, that once an IP packet hits zero in the TTL, the router will drop the packet.
For local traffic (traffic that is never meant to leave the local subnet), a TTL of 1 is used.
If we didn't have TTL in our IP packets, they would just loop without end.
Incidentally, this is the problem with Layer 2 bridging. Layer 2 traffic has no TTL, and that is why Layer 2 network can have those pesky bridging loops.
Wiki User
∙ 6y agoThe purpose is to avoid the packet from moving around the network indefinitely, in case there are routing problems - especially routing loops.The way it is dealt with is that every router decreases the TTL by one, when forwarding the packet. Once the TTL reaches zero, a router will discard the IP packet.
Add your answer:
Earn +20 pts
What field of the IP header does the Tracert program use to get the IP address of routers in the path?
it uses the time-to-live (TTL) field.
Which field of ip address is changes from router to router?
The TTL will be reduced by one every time it passes a router. Because this changes the IP header, the checksum also has to be recalculated.The TTL will be reduced by one every time it passes a router. Because this changes the IP header, the checksum also has to be recalculated.The TTL will be reduced by one every time it passes a router. Because this changes the IP header, the checksum also has to be recalculated.The TTL will be reduced by one every time it passes a router. Because this changes the IP header, the checksum also has to be recalculated.
Which IP packet field wiil prevent endless loops?
Time -to-live
Which IP packet field will prevent endless loop?
Time-to-live (TTL)
Which field of the IP Packet indicates the remaining life of the packet?
TTL- Time To Live
What does the protocol field in the IP header identify?
The protocol field, in the IP header, identifies what kind of data is in the IP packet - the upper-layer protocol. For example, if the code is 6, that means that the data is a TCP segment.
What in an IP packet header contains information that prevents a packet from continuously circulating around a network?
See time-to-live (TTL) packet
The maximum size of an IP datagram including the header is?
The datagram length field in an IP header is 16 bits in length. Therefore, the maximum datagram size an IP datagram can support is 2^16 - 1 = 65,535 bytes
Which field in the IP packet header allows checking for data transmission errors?
time to live
If the Protocol field in the IP header has a decimal value of 17 it means that the higher level protocol using the services of IP is TCP?
no, service of UDP
How many bits does the DSCP use in the IP header?
how many bit header Ip v4
What is a layer four header?
In the commonly used TCP/IP communications, that would either be a TCP header, or a UDP header.In the commonly used TCP/IP communications, that would either be a TCP header, or a UDP header.In the commonly used TCP/IP communications, that would either be a TCP header, or a UDP header.In the commonly used TCP/IP communications, that would either be a TCP header, or a UDP header.
