Hello, i have a simple question.
If I set for example ARP timeout for 10mins and no traffic is received or transmited for 10hours. So questions do ARP timeout after 10mins will refresh it's ARP table with ARP request or no even with no traffic ? Can't find clear documentation on that... thanks.
may i know what device are you working on and the ios version?
and what do you mean by no traffic? are you unplugging the cable?
it's just theoretical question.
Just imagine two standard cisco Routers connected to each other. And all the features like CDP is turned off. The ARP will renew or not ?
It will not renew automatically without an arp request. Local addresses should still show up in the arp table though. Once the dynamically learned address hits the 1440 minute threshold, it will drop from the table. Addresses that are set with static arp and local addresses will always stay in the table and will not drop out.
im reading a good chapter abour ARP here:
what interest me the most is the way the writer use the simple analogy:
"The alternative to direct mapping is a technique called dynamic address resolution. To understand how this works, we can consider a simple analogy. I'm sure you've seen limousine drivers waiting to pick up a person at the airport they do not know personally. (Well, you've seen it in a movie, haven't you?) This is similar to our problem: they know the name of the person they must transport, but not the person's face (a type of “local address” in a manner of speaking!) To find the person, they hold up a card bearing that person's name. Everyone other than that person ignores the card, but hopefully the individual being sought will recognize it and approach the driver.
so, theoritically, based on my understanding, if there is no traffic that needs to be transmitted, the arp protocol must not start itself.
but nowadays, in the real world, even if you only connects two cisco routers without having any client and disabling cdp, there are some protocols that depends on ARP, such as dhcp, dynamic routing protocol, or multicast routing, etc.