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Quels sont les problèmes possibles avec des durées de bail DHCP très courtes (< 1 min) ?

ayi

Nous avons a network setup for a demo, qui lasts about 15mn. Our DHCP server is configured to assign ~ 100 addresses (max number of simultaneous connections ou our AP) ... mais depuis people might come et go très quickly we need to keep le lease time très short in order to free le IP addresses et allow autre people to connect.

Initially I wanted to go for a lease time as short as 25 seconds, considering that le demo is assez short, et to be sure that no IP will be "abusively" reserved by le DHCP server ...
Cependant, Je suis afraid of plusieurs things.

First, le impact on le load of le network.

Second, J'ai read here et there that there might be certains "weird" issues avec time leases ci-dessous 1 minute (e.g. What is a good DHCP lease timeout configuration).

Does somebody know what can be le différent problems avec using such a short time lease? What is le impact on le network? What would be a short mais safe lease duration to use?

ayi

With a très low lease time you will see an increase of network traffic, particularly broadcast traffic as le "discover" et "offer" phases of DHCP are layer 2 broadcasts. How much of an issue this is depends on beaucoup de factors such as le size et complexity of le network, latency, performance of le DHCP server, etc. Keep in mind DHCP clients do pas wait jusqu'à leur lease is expired to essayez de renew it. So si you gave me a 60-second lease Je vais be talking to le DHCP server (potentially) chaque 30 seconds to renew it.

As for "weird" issues, anything goes. Different DHCP clients will behave differently. Some may handle it fine, certains may have problems renewing so often et fail. Perhaps there are clients qui get a lease et simply sleep for a certain period of time alors check si they need to renew ou toss le address si it expired. If le sleep is longer than le lease alors le system will keep le IP longer than it is allowed to. I n'ont pas seen that issue avant mais J'ai seen things like le IP a client requests in le "request" phase being différent than le one le server gave it in le "offer" phase mais le server actually gave le client le "request" IP, qui was déjà in use. Never under-estimate how poorly software can be written.