Questions tagged [router]

For questions about network routers, devices that forward data packets between computer networks, commonly at the network layer (layer 3) of the OSI model.

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InterVLAN routing on Cisco router with multiple trunks [duplicate]

I recently came across a scenario where I wanted to (ab)use a Cisco router (ISR 4331) as a layer 3 switch. The router is directly connected to two switches. The connection between each switch and the ...
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In France , what language is the Cisco IOS for routers and switches?

If I accept a Network Engineer job in France, what language will the Cisco , Juniper, etc, IOS communicate in? If it is in French, is there an acceptable workaround that I can install in routers that ...
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Multiple IP address on an unmanaged switch

Sorry if this question have been already asked. My ISP is providing multiple public IP's on an interface. Can I use an unmanaged switch to conect to ISP's interface and then connect this switch to ...
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If router is a layer 3 device how can it have an application interface (GUI)?

It is said that layer 3 devices such as routers do not have an application layer. But whenever I want to configure my home router I punch in the IP address and open up its graphical user interface. ...
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Ping ICMP is always sent to the same PC via switch from router

I am quite new to this world and I'm currently to understand why an ICMP ping is always sent to the same PC. In this case, I am sending a ping from PC_F to Server PT. ping 192.168.1.2 In the ...
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1 vote
3 answers
109 views

Why does a queue of a network device like router starts to fill up if the arrival rate equals the transmission rate of the outbound link?

In the book "Computer Networks: A Top Down Approach by Kurose" it is written that when the traffic intensity approaches 1, the average queue length gets larger and larger. Traffic intensity ...
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-1 votes
2 answers
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How does the computer detect the routers Around? [closed]

I can see any wireless modem around(networks) in internet access icon , How routers say to my computer "hey I am here ?" is it port forwarding ? upnp ? IGMP ? which protocol they send and ...
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How is it possible that CSMA/CA works in areas with a lot of users within a small radius (e.g. rallies, concerts, etc.)?

My understanding of CSMA/CA is that devices listen until a Wi-Fi channel is idle before sending packets. If a collision still happens, then the devices waits a random interval before attempting to ...
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1 answer
573 views

Possible causes of ICMP Destination unreachble - Port unreachable

Are there any other causes, apart from the specific port to be reached being closed, that can lead to an ICMP Destination unreachable - Port unreachable message? What are possible reasons for this ...
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1 answer
198 views

Can't ping neighboring router OSPF

I have set up an OSPF network and I cannot ping from the Edge router to Main Branch.
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1 answer
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Simple lab setup in Cisco Packet Tracer

I've just started my journey into the netowrking world. I am following Ross Bagurdes course of CCNA. I am trying to setup a simple lab in Cisco Packet Tracer. To see the lab please check the picture ...
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1 vote
1 answer
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How to uniquely identify device on LAN

I am concerned with uniquely identifying devices on the LAN. This is useful for making sure unauthorized devices did not connect to the network and try to access the router. This is also useful for ...
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ICMP packets are being dropped while pinging

I am pinging from one of the Juniper L3 interfaces to another with a rapid ping count of 10000 packets. It's a direct 100G optical connection and I am seeing 10-15 packets being dropped by the end of ...
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3 votes
3 answers
507 views

Multihoming with two 'good' providers - load sharing strategy?

We get two 100G links, one from each provider and our aggregate traffic is sub 100G. The rationale is one provider can fail and the other will pick up the slack with zero degradation. Our traffic ...
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1 vote
2 answers
88 views

Proxy-ARP when the destination device is connected to the same layer-2 switch, but belongs to a different subnet

I have recently learned about Proxy-ARP and am slightly confused about what would happen in the following scenario. Let's say I have two host devices A (IP: 10.0.0.10/24) and B (IP: 10.0.1.10/24) that ...
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Tagging a VLAN or not

I want to create a wi-fi network for guests using access points. I asked to the IT provider a dedicated network with its VLAN and it is: 172.16.0.0/24 VLAN ID 344 The above network is configured on ...
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How does a switch know when and how to forward traffic to a router

I generally understand how L2 switching works. I want to understand how a switch and router work together to send traffic to a device off the L2 network. For example. Computer A tries to send ...
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L3 Switch acting both as a router and as a switch for the same packets

I am trying to figure out if an L3 switch is able to act as a switch and as a router at the same time for the same packets. Consider the following architecture: I would like to set up VRRP for both ...
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Why Ping Reply Succcess from different subnet IPs

In the university lab, i manually added IP in two ubuntu machines. PC1 IP 10.129.2.33 255.255.0.0 and PC2 IP 10.129.2.165 255.255.255.0. I connected first both computers with direct ethernet cable ...
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1 answer
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Two routers connected with a serial line, why they can ping each other without clock rate setting?

I'm pretty new to networking and still learning CCNA stuff. I'm reading a book and as I understand, when you are connecting two routers using a serial line, one router is considered DCE and the other ...
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1 answer
177 views

IP masquerading and nat

what is the difference between IP masquerading and nat? do both of them have the same limitation? in the line "IP masquerading cannot provide full internet connections to the hosts which hide ...
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1 answer
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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 ...
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What is the difference between these two different network security devices?

I have a choice between these two network security appliances, however the only difference I can see is the year and I don't know what that year means. SONICWALL TZ300 WIRELESS-AC SECURE UPGRADE PLUS ...
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Dual Juniper MX80 problem

We have 2x Juniper MX80 routers with only one currently being actively used. Second one is waiting to take over in the event of disaster. We also have two ISP's that deliver network to our MX80. We ...
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Is it possible to configure DHCP on a router or UTM firewall for the multiple VLANs on L3 Switch?

I'm working on expanding our office network to accommodate more users/devices. Currently we have the DHCP configured on a UTM firewall(cyberoam ing50) device(cum router) providing IP addresses for ...
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1 vote
0 answers
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1941W wireless clients losing DHCP IP address [closed]

I am attempting to 'extend' a 192.168.1.0\24 network with an experimental network 192.168.10.0\24 using a 1941W router. I have configured 1941W to distribute a 192.168.10.0\24 network, with WLAN ...
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2 votes
1 answer
270 views

Cisco, Router can communicate; hosts cannot

I am learning CCNA related tasks, I have picked up a Cisco 1900 Series router. I am attempting to set it up behind my existing router (Comcast standard router). My "Real" network is 10.0.0.0/...
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1 vote
2 answers
225 views

Huawei AR207V - can't set IP address

I can't set an IP address on a Huawei AR207V router because it rejects the "ip address" command. It's a used but factory reset unit, I'm currently connected on the serial port no other ...
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0 votes
1 answer
7k views

"Destination host unreachable" when pinging a pc from another network

I tried to build a simple network in Packet Tracer and I get "Destination host unreachable" when I try pinging a PC from another network. Pinging PCs from the same network works. When I use ...
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0 votes
1 answer
57 views

What is BTU/hr gauge of Cisco ISR4461/K9?

I searched everywhere but couldn't find it. If anyone knows the system, can answer? How much BTU (British thermal unit) /hr uses by this router.
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1 answer
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NAT cannot communicate with 2 network

I have configured BGP for routing and NAT for HQ and Branch. I can ping from windows / server to public IP and also Linux Mint ping to public IP. but, I cannot ping / communicate between network HQ to ...
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2 votes
1 answer
300 views

Is it possible to have a second ASBR in my OSPF area 0?

I have three routers in area 0, two of which are connected to separate WAN circuits. I have one router that is sending the default route but when I try to add a second router with the configuration ...
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Where can one find how much memory is currently allocated to logbuffer?

Do you know where it can be checked, how much memory is currently being used by the logbuffer? some-switch#show log | i Buffer|Trap|udp Buffer logging: level debugging, 2268 messages logged, xml ...
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1 vote
1 answer
646 views

BGP Best Path Selection Algorithm

According to this cisco document (https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13753-25.html), shortest AS_PATH is the #4 algorithm in the sequence to evaluate, out of 13 ...
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Cisco ip helper-address

I am looking at the DHCP documentation and i cannot seam to find how to configure the router to use a loopback interface as the relay-agent. My objective is to use option 82 so that the dhcp server is ...
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Static Routing - host to host ping does not work (MikroTik)? [closed]

I'm trying to do static routing using actual devices. Below is my setup: The left router is a MikroTik RouterBoard hAP lite. The right router is a MikroTik RouterBoard hAP ac. I want to ping from ...
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6 votes
2 answers
1k views

Undo last command(s) in case of losing connection to a Cisco Router

I would like to configure an interface on a remote Cisco router (ISR 4000 series) with IPsec. The only way to connect to it is through the interface that I am trying to encrypt. I want to ensure that ...
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1 answer
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Is it possible to assign an IP to a tagged dual-mode port (Brocade)

I have a router (ubiquity USG) and a Brocade FCX648 Layer 3 switch. (I have a second one in a stack, but that's unrelated). The end goal is to be able to connect the switch to my router, provide IPs ...
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Who initiates PPP Keepalives after PPPoE session is Established between Modem and BNG?

Hello Everyone, In case of DSL Modem , normally service providers employ PPPoE connection between Modem and BRAS (BNG). We all know that when Modem dials , it goes through PPPoE stages namely 1 ) PADI ...
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1 vote
3 answers
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Combining NAT an tunneling

I was reading a text and a doubt came to mind. Suppose there is an interface in a router that implements NAT. That same interface is the extreme of a tunnel. If I was to send a message through said ...
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1 vote
3 answers
114 views

One client: static IP vs Static lease DHCP vs. DHCP limited range to 1 slot

I want to attach one client (only 1 maximum) to network router ethernet port. I want to always know the client's IP address, for my port forwarding settings. Using DHCP with range the client IP could ...
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1 answer
986 views

Factory reset Cisco N520-4G4Z-A

I'm having some issues doing a factory reset on above mentioned Cisco box. I've tried several different key combinations and unfortunately previous owner does not remember password The examples on ...
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1 vote
0 answers
52 views

Mistakenly added switch configuration on Cisco router 2951 so now it is showing gibberish data on CLI

I have Cisco 2951 router in which my colleague mistakenly uploaded switch configuration from tftp server. Now it is showing gibberish data on CLI when it boots up. I tried to get into the ROMmon mode ...
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2 answers
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How does an L3 Supported Switch differentiate L2/L3 Packets?

I had a managed or layer 3 supported switch (it can process both layer 2 and layer 3 packets). Now a packet from a connected host comes to it, sending traffic. How does the switch decide to process it ...
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BGP unnumbered on P2MP link

I'm wondering what will happen if BGP unnumbered session is configured on a link that has multiple routers on the other side which are both IPv6-capable and will both reply on RS and produce RA ...
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1 vote
1 answer
209 views

GNS3 can not ping from ethernet interface to serial interface

So I am doing a Lab for one of my classes involving ipv6 and routing using EIGRP. When I set-up the network and assign the router interfaces with IPV6 address I get an issue pinging the whole network. ...
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Does the control packets flow into a router/switch through forwarding plane? [duplicate]

I know there are two platforms in any networking device separating the control packets from the traffic, which I call control plane and data plane. My question is, how does the control packets enter ...
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2 votes
2 answers
1k views

How to block advertisement of a prefixes recieved from 1 BGP neighbor to another

I have a eBGP topology as follows: RTR1 ------ DUT ------ RTR2 (AS100) (AS200) (AS300) I do not want any routes sent by RTR1 to be advertised into RTR2 by DUT I do not know what exactly the ...
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Switch vs. Router and sequence of OSI Model [duplicate]

As I understand it: A switch (layer 2) seems to define a LAN and a router (layer 3) enables communication between distant LANs. A device on a LAN will give it's MAC address to the switch upon ...
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1 vote
3 answers
5k views

Difference between Reverse Proxy and Port Forwarding

Well both reverse proxy and port forwarding looks for any incoming packets destined to a particular machine which is present in local network. How both of them are different ?
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