Questions tagged [arp]
For questions about Address Resolution Protocol (ARP). ARP resolves OSI layer-3 addresses to OSI layer-2 addresses.
312
questions
0
votes
0answers
12 views
Arp Access-List Without An Interface [duplicate]
I have dhcp snooping an arp inspection setup on my VLAN. I have a number of clients that need to be statically set on this VLAN but still plug into a DHCP access port on the VLAN. I have ip dhcp ...
0
votes
1answer
34 views
IP Snooping\ARP Inspection With Static Devices On DHCP VLAN
Consider this network:
I have enabled DHCP snooping on my system. Switch A has the DHCP connected and the port on VLAN 70 for DHCP has been trusted to allow for reading the database and passing ...
1
vote
1answer
49 views
VPN with Cisco virtual ASA on Azure not routing correctly
I've deployed a Cisco virtual ASA in Azure to use as a VPN server. For simplicity, I'm using just the management interface as the lan for the time being (10.2.0.4 is the interface). I want to use the ...
1
vote
3answers
48 views
Why do IP(v6) routes require a next hop IP(v6) address and not just a MAC Address?
My understanding of how you "ask" a router to route a packet for you is that you simply put the IP(v6) address of the destination host and the MAC address of the router you are routing via ...
0
votes
2answers
56 views
ip dhcp snooping Kills DHCP Ports
I am working on implementing DHCP Snooping on my switches and have found that when I do so it kills the DHCP connection to the clients. The network is as such:
The server with DNS is providing DHCP ...
2
votes
1answer
20 views
Unable to Communicate from server to other servers after migrating from existing firewall to new firewall
In our existing environment we had migrated old firewall with new firewall after this activity . we had faced connectivity issue . From servers unable to reach other servers . Post clearing ARP table ...
0
votes
1answer
21 views
issue regarding broadcast mac address
I read a line saying {Routes do not forward packets coming from one interface having broadcast mac address
(FF:FF:FF:FF:FF:FF)}
what is meant by one interface in that line?
if router cannot broadcast ...
1
vote
0answers
65 views
EVPN+VxLAN strange silent host issue
EVPN+VxLAN very strange silent host issue
I have very basic EVPN+VxLAN design where i used OSPF/Multicast/BGP/vPC technologies to build small size datacenter. L2VNI working great without any issue. I ...
0
votes
2answers
34 views
Broadcast times for new devices in ARP protocol
How many broadcasts are needed in ARP protocol for one new device send to another new device to get necessary ARP table entries for lookup in one switch?
1
vote
1answer
66 views
Suspicious flood of ARP requests [closed]
I'm trying to review a Wireshark capture and it seems the network is heavily flooded with ARP requests that make no sense to me.
The destination is not "Broadcast", but some unknown DELL ...
1
vote
2answers
64 views
What role is ARP playing for a internet request?
For me it is not clear how the internet is working. Let's say we have host (local IP:192.168.12) and the gateway/router (local IP: 192.168.0.1 / extern IP: 62.1.2.134)
Now the client (192.168.0.12) ...
0
votes
0answers
11 views
ARP Table Entry [duplicate]
There are 2 devices - A & B in a LAN. They have no entries in their ARP cache. Device A sends an ARP request to know the MAC address of device B, considering that the ARP request does not have an ...
1
vote
1answer
40 views
How does router know MAC addresses of computers that are connected to a separate switch? [duplicate]
i am a newbie but i need to understand this ARP thing.
In my company we have a router that has 3 switches connected to it. On the switches there are more than 100 hosts.
I know that switch learns and ...
0
votes
1answer
43 views
Much ARP requests from Cisco ASA 5510
An employee of the ISP writes to me that a lot of ARP requests from us go to them.
ISP equipment log:
07:47:27.732242 ARP, Request who-has AAA.BBB.CCC.213 tell AAA.BBB.CCC.53, length 46
07:47:27....
1
vote
2answers
92 views
How does the ARP table know to update if two hosts flop IP addreses?
When hosts on the same local network communicate, they manage their own ARP tables which translate between IP addresses and MAC addresses. Thus when computer A needs to send data to IP address ...
3
votes
1answer
297 views
ARP Router issue
I have a question when a Router receives ARP request to a host that dosen't exists on the forwarding table for that router does the.
And this Router is not the next hop either will the Router continue ...
1
vote
2answers
83 views
Intermittent Network Performance Problems
I've been dealing with an intermittent issue in my network for several weeks now.
Symptoms:
Periodic "Destination host unreachable.", and similar errors when pinging. The following is ...
0
votes
1answer
37 views
IP datagram route through a network utilizing ARP
Suppose I want to send an IP datagram from node D to node C . Each step I also want to list the MAC addresses of the source and the destination , as well as the source and the destination of the IP ...
0
votes
1answer
30 views
How might ARP impact the UDP communication and what is a scenario i can reproduce to check/understand it?
I was wondering which impact the ARP protocoll might have on a UDP communication. I am learning for an exam and trying things out with mininet (linux )/ wireshark to understand the dependencys between ...
2
votes
1answer
307 views
How to capture mixture of packets with and without VLAN tag over LACP with tcpdump?
Given following configuration in Linux:
bond0 in LACP (802.3ad) mode with two VLAN networks running over it.
bond0.111 configured with static IP
bond0.222 configured with DHCP
How to capture packets ...
1
vote
3answers
146 views
Why is in all arp table snmp oids an interface index before the ip number?
When I want to get arp information about a single ip number or subnet, I have to snmpwalk the whole arp table, as some oid architects had the "great" idea to always insert an interface index ...
2
votes
2answers
64 views
When traffic is intiàted from pc is ANDing process or ARP process start working first
When traffic is initiated from desktop which process starts first; the ARP process or ANDing process?
1
vote
2answers
66 views
Is the outgoing interface of a router in the same Subnet as the Incoming interface of the NEXT HOP router?
In the TCP/IP Volume 1, it is stated that ARP works only on the same subnet. Does this mean that the outgoing interface of a router is necessarily on the same subnet as the incoming interface of the ...
0
votes
1answer
31 views
Who can get ARP packets? [duplicate]
I'm new to networking.
And as far as I understand about ARP messages, Alice can only send ARP to Bob if two are connected.
But if Alice and Bob are connected to a router, but not connected to each ...
0
votes
0answers
22 views
MAC flooding for new host in L2 domain [duplicate]
This hypothetical network has one dumb L2 switch and two hosts A and B connected to it. CAM table entries on the switch are all populated and both hosts have ARP entries for each other.
Now if a ...
2
votes
3answers
80 views
How are packets ( received from the server ) sent to the host from the gateway ( which is present in the host network )?
If the host is receiving packets from a server, these packets have a destination IP address of the host and it is first received by the gateway present in the host network. Now the gateway checks the ...
0
votes
1answer
60 views
Broadcast ICMP and gratuitous ARP
When sending an ICMP broadcast, all nodes can respond. is it the case of the sender too?
If it's the case then:
Is it specified somewhere that the sender should respond with gratuitous ARP when the ...
2
votes
2answers
79 views
Can a switch send a frame back to the source host because of a loop?
First, I understand how switches work when they receive a broadcast frame. They will record the source MAC address on the incoming port (put it in the CAM table) and then flood the broadcast frame out ...
1
vote
2answers
88 views
Question on ARP
I'm not really sure if the IP-MAC addresses for the router get stored in the ARP cache of endhosts, hence the question.
0
votes
2answers
103 views
ARP-Request - Reply from the perspective of a router
Presume I have a route table with such entries:
typedef struct route_table_entry {
uint32_t prefix;
uint32_t next_hop;
uint32_t mask;
int interface;
} route_table_entry;
I have a ...
-1
votes
1answer
44 views
ARP protocol, how it should behave [closed]
I am trying to implement the ARP protocol by myself, but I'm not sure how it should behave, how I should craft an ARP request. How does it work and why it should work..
I tried to research this on ...
1
vote
1answer
118 views
Wireshark does not capture free arp packets (opcode2)
Wireshark does not capture free arp packets (opcode2). Only arp announcement packages (opcode1). While running wireshark on the windows 10 computer, I turned on the other computers, but wireshark does ...
3
votes
0answers
51 views
Arp Protect in dynamic VLAN environment
I am using 802.1x authentication with dynamic Vlan assignment(CPPM). As you may know, when a user logges in to their computer, SW attaches the user port to related Vlan. Thinking the scenario in which ...
1
vote
1answer
59 views
How does the swtich know if a packet needs layer 2 switching or layer 3 routing?
I have a network topoloty as follows
A --------- B --------- C
/|\ /|\ /|\
/ | \ / | \ / | \
A1 A2 A3 B1 B2 B3 C1 C2 C3
A, B, C are ...
5
votes
5answers
3k views
How does a host in one subnet know to forward the packet to the router MAC, when trying to send a packet to another subnet
I am trying to understand the ARP protocol and I could not understand the above. Consider the topology as follows:
H1(1.1.1.1) - (1.1.1.0)R(2.2.2.0) - H2(2.2.2.2)
My understanding is that if the ...
2
votes
1answer
59 views
How is traffic correctly routed in Site-to-Site VPNs where all sites are on the same subnet?
http://rockhoppervpn.sourceforge.net/ref_site2site_bridge_6.html
The diagram on this page shows all 3 sites using the same subnet, 192.168.0.0/24. Let's say on the hub site where 192.168.0.10 is the ...
3
votes
2answers
642 views
What's the difference between “show arp no-resolve” and “show arp” in Juniper?
What's the difference between show arp no-resolve and show arp?
If I add the no-resolve, what's the difference of it?
0
votes
0answers
16 views
ARP traffic for devices in same LAN but different subnets [duplicate]
Given a LAN with 5 devices (a,b,c,d,e). Where devices a and b are in one subnet and d,e,f are in another. Will an ARP request broadcasted by a looking for device b reach devices d, e ,f as they are ...
2
votes
3answers
368 views
Will pinging the multicast “all hosts” IP 224.0.0.1 fill my ARP cache with all hosts on my current subnet?
Just wondering in case I ever have a want / need to see all the hosts on my subnet.
1
vote
1answer
134 views
ARPs in WIFI Interface Monitor Mode
I set my WIFI interface to monitor mode.
I did not expect to see any ARP requests.
Can someone explain why there is ARP traffic?
1
vote
1answer
48 views
Packet analyze on router does not match client and server
thank you for your time.
My (virtual) network has 3 objects : a client, a server and a router between them.
I'm sniffing the traffic on the 3 machine with the command
tcpdump -i any -s 0 -w [path]
...
0
votes
1answer
167 views
How to get IP address of device from its MAC address on network?
Though it seems possible duplicate of this question. But the need to ask this question again is to simplify the scenario and the demands to just finding the IP address of the device.
The network in ...
1
vote
1answer
218 views
Arpping responding with Cisco ASA interface mac address and mac address of machine
For some reason our Cisco is responding to arp requests between machines on the same switch. It's not breaking anything but it is slowing initial connections. I've been making a lot of changes on the ...
1
vote
1answer
182 views
what are Hardware size and protocol size in ARP header? Attached image
While working on packet capture for a simple scan, just had a look at packet capture and want to know what does hardware size and protocol size means in a ARP header?
5
votes
1answer
161 views
Getting lot of unwanted broadcasts on my network
I am pretty new in Networking (noob), while I was monitoring my network using Wireshark, and I found that there is a lot of broadcasts happening all over the network, broadcast on Local network ...
1
vote
1answer
65 views
How data travel from a node to a destination IP address? [duplicate]
Let's say I have a lot of devices which connect to a single switch, and the switch itself connects to a router which provide Internet connection.
Whenever an application on a node needs to ...
0
votes
1answer
228 views
What is passive ARP learning and how does it work?
Is it the same thing as gratuitous ARP? I cannot find any good sources on the topic.
0
votes
1answer
2k views
Devices in same vlan cannot ping each other - ARP Issue [closed]
The environment is running with Nexus 9K in NXOS mode. Both are in vPC mode and running hsrp with N9K1 active and N9K2 standby. Due to vPC both nodes are running Active/Active for HSRP.
Now the ...
0
votes
2answers
616 views
How the broadcast MAC address accomplished?
The Layer 2 broadcast is the destination address of the Layer 2 package is FF-FF-FF-FF-FF-FF.
I have a question about the broadcast MAC address.
you see the ARP request, it send the destination MAC ...
5
votes
1answer
482 views
Cisco DAI / arp inspection limit
During a recent penetration test it was found that we didn't have dai set quite as tight as possible to fully stop things. I'm running Cisco 3750x if it matters.
The interfaces are configured with ...
