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Questions tagged [arp]

Address Resolution Protocol is a layer 2 networking protocol used for resolving layer 3 addresses (such as IP addresses) into layer 2 addresses (such as Ethernet MACs). It is used by network devices when communicating with devices on the same layer 2 network.

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Neighbour table overflow on Linux hosts related to bridging and ipv6

Note: I already have a workaround for this problem (as described below) so this is only a "want-to-know" question. I have a productive setup with around 50 hosts including blades running xen 4 and equallogics providing iscsi. All xen dom0s are…
tim
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How to find the process which causes the arp request?

When i run tcpdump in the gateway, i get a lot of arp requests originating from the gateway itself. I wonder know why this happens. How can i find the process that causes these arp requests? $ tcpdump -n arp tcpdump: verbose output suppressed, use…
Ping Yin
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Why does Linux answer to ARP on incorrect interfaces?

I have the following Linux networking setup: there is an eth10 network interface with the assigned address 10.11.0.1/24. Then there is a tap0 network interface with assigned dummy address 0.0.0.1/32 (I assigned a dummy address to bring the interface…
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When do STALE arp entries become FAILED when never used?

root@openwrt:~# ip -s -s -4 neigh show dev lan 10.64.42.121 lladdr b8:20:00:00:00:00 used 6387/6341/6313 probes 1 STALE 10.64.42.157 lladdr b8:20:00:00:00:00 used 24/813/19 probes 1 STALE 10.64.42.12 used 29066/30229/29063 probes 6…
Fox
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Dynamic ARP Entries turning into Static ARP entries

I recently acquired a client that has a strange ARP caching issue on one of thier servers. I have a server that will eventually start turning it's dynamic ARP entries into static ARP entries. This causes problems because when the machine that has a…
Zach
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Network throughput issue (ARP-related)

The small college where I work is having some very strange network issues. I'm looking for any advice or ideas here. We were fine over the summer, but the trouble began few days after students returned to campus in force for the fall term.…
Joel Coel
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ARP reply vanishes from br0 to tap0 using OpenVPN in bridging mode

I have setup a linux box (on an esxi5) which acts as an OpenVPN server. the server is configured to use bridging for the clients, which essentially works, with one exception. If the client pings some machine on the network which is not the server…
fen
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linux routing bug?

I have been struggling with this not easily reproducible issue since a while. I am using linux kernel v3.1.0, and sometimes routing to a few IP addresses does not work. What seems to happen is that instead of sending the packet to the gateway, the…
Balázs Pozsár
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Why my laptop sends ARP request to itself?

I have just started to learn about protocols. While studying the packets in wireshark, I came across a ARP request sent by my machine to my own IP. Here is the details of the packet : No. Time Source Destination …
user58859
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ARP/Mac address table

What is the difference between a mac address table and an arp table? Is it correct to say only one arp cache is kept for each switch which self learns to forward information to another host, and every host on the network has its own mac table, which…
user171131
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Is it possible to use proxy-arp back to the same interface?

I have a WiFi Access Point connected to a Linux Router. The Router is itself connected to the Internet. For multiple reasons (mostly to control security and quality of service), I want to force all the users' traffic to go through the Linux…
MiniQuark
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Is it possible to match an internal IP address to a switch port?

I'm trying to find a computer that has a certain IP address on our internal network. I have identified the computer name from DNS, but in this case it does not help me. Just wondering if I can somehow tie the IP to a switch port, and track it from…
Brent
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How to query the age of an ARP-cache entry in Linux

How can I query the local ARP-cache on my Linux-machine to see when a specific ARP-entry was learned and/or updated the last time?
nitram
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Cannot ping B from A until B pings A

I have a server cluster all connected on a local network(all physical machines, not virtual). When trying to ping from Server A to B, I get a Desitination Host Unreachable. I can ping from B to A no problem, which then allows me to ping from A to…
Eumcoz
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How do I poll the ARP table with an SNMP OID?

When you need to poll the ARP table of a device, conventional wisdom is to use ipNetToMediaPhysAddress or atPhysAddress; however, both of these OIDs are deprecated according to Cisco's documentation. These OIDs work just fine; however, I'm building…
Mike Pennington
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