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Questions tagged [interface]

For questions about a physical or virtual interface on a network device. For instance: Interface configurations, troubleshooting and security.

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Command for interface uptime

Is there any command to find out how long a particular interface has been up on a cisco switch ?
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1 answer
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VLAN routing on the same subnet

Consider following situation: You have 10.3.0.0/16 network without any VLANs. Now You want to divide it... You want Your IT department be able to reach the entire network, but sales department only ...
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4 votes
1 answer
261 views

Copying IOS from TFTP problem

I have a Cisco 4503 switch that had its IOS completely wiped. I have managed to boot from TFTP. the instructions I have tell me to switch the ethernet cable from the management port to a standard 10/...
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2 answers
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Question about subinterface DHCP relay CISCO

I want to make 4 PC got DHCP IP address No problem with left side, but right side 2 PC can't get IP automaitic. I think the problem is DHCP Relay. How can I use ip helper-address for subinterface of ...
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1 vote
2 answers
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What's the different between a "mask" in route table and interface?

if we took Windows as an example, we can use the command "netstat -rn" to show route table as follows: IPv4 Route Table ===================================================================...
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2 votes
1 answer
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Unable to disable CRC check on Cisco 2960-X

I have a 48 port Cisco 2960-X running IOS Version 15.0(2)EX5. I'm trying to connect it to a Ubiquiti EdgeRouter4 using a Ubiquiti DAC Twinax cable.. I'm aware that this is technically not recommended, ...
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2 votes
2 answers
112 views

Unable to add an abbreviated IPv6 to a Cisco router

I am very new to networking and playing around with GNS3. I am trying to configure a router to have 2 IPv6 addresses in a single interface (as far as I understood, this is possible with IPv6) I ...
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Is It possible to make Router On A Stick with two physical interfaces in the router?

If we try to implement router on a stick (ROAS) for try interVLAN communication, we must to use one Phisical interfase and split it into several "logicals" interfaces. Until Now all right. ...
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can LAN port have multiple IP addresses of same subnet mask or different subnet mask

Can the router's ethernet interface have multiple IP's of the same subnet or different subnet mask? If yes what's the use?
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What does network interface do? and what's difference between a network interface and a network interface card (NIC)?

I'm a little confused about the network interface. Based on my understanding, a network interface does the translation between link-layer and internet layer, and does the ARP. Is that right? Also what'...
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100 views

Adding Second Interface with Different Public IP for Same Internet Connection

We have a situation that I'm not sure how to proceed correctly. This location is currently utilizing two different firewalls - a Sophos XG 310 and a Sonicwall NSA 3500. The way this was originally ...
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1 vote
2 answers
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Basic conceptual questions about network interfaces

I have some basic questions as I am trying to understand the concept of network interfaces a bit better. Is network interface same as network interface card (NIC)? If not, what's the difference. What ...
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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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Understanding the Burst Size against policer for 1G/10G interfaces in Juniper MX

We are facing one confusion with regards to burst size value against rate limit or policer in Juniper MX. Need to understand two things :- (1) Is the burst size limit defined in firewall policer ...
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2 votes
0 answers
728 views

10G Interface on Juniper MX Stops Transmitting Output Optical Power

We have been facing an issue on Juniper MX series router. We have 10G interface on our router. Its does not matter whether interface is connected to DWDM or interface itself is a dark fiber. The end ...
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1 answer
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Accessing an interface range that spans beyond one stack on a Cisco Switch

I want to configure Interfaces 0/3, 1/2 and 1/3 for example. Using interface range gig 0/3-1/3 did not work, is it simply not possible or is there a different syntax? EDIT: Of course aside using ...
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Routers FastEthernet interface clock autonegotiation protocol

In routers, for serial interfaces, we need to manually set the clock at the DCE router so that the ends of the connection can communicate. I know that in this way we are using time-division ...
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I still can't understand how routers work

I've seen a topology that has 1 router for each network, for example: Network1: 192.168.1.0 192.168.1.2/24 PC1 -> 192.168.1.3/24 PC2 -> 192.168.1.5/24 SWITCH -> 192.168.1.1/24 ROUTER 192.168....
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1 answer
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VLAN Subinterface Removal - CISCO ASA

The below are the configuration of the subinterfaces in Cisco ASA firewall and currently sub-interface 0/1.1 is only passing traffic and I need to remove 0/1.2 configuration from here as it is unused. ...
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1 answer
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Multiple mac adrress on one cisco switch interface

How can i config Multiple mac address on one cisco switch interface? (I have 3 laptops and i connect only one laptop every time(I switch between them), and i want to config only one interface with the ...
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1 answer
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JunOS: FPC Major error alarm

I hope everyone is doing fine! This morning I've run into a problem. My uplink interface went down for unknown reasons. Upon checking system alarms I see this: show system alarms 1 alarms currently ...
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Steps on troubleshooting a network

If I have to troubleshoot a network stating that one of the interface is not working (i.e, a link is down), what steps would I need to take to make it working again?
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Fiber dBm transceiver power level at warning

We have cisco nexus 9000 and one of 40G interface showing port transceiver power level at warning when i check on command line i found following. Question: what is the normal power level for ...
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Change name interface [closed]

Sorry for my English.... I want to change the interface name, what I don't know sure the steps.... First I should know my interface name and mac from it, ip a Seconds, down my NetworkManager, ...
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2 votes
1 answer
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Link Aggregation from Cisco to Palo Alto using 10 gig interfaces, port on Cisco shows "waiting to be aggregated"

I am trying to bundle two 10-Gig interfaces on PA-3020 to Cisco Cat9300. Previously, I had bundled two Gigabit interfaces on same devices and everything worked fine. But now, when I try to configure ...
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Cisio interface naming rule

I'm very new to networking. I noticed in GNS3 lab environment, if I want to configure IP address for an interface of a router, I can use int f0/0 or int fastEthernet 0/0. What's the naming rule here? ...
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2 votes
2 answers
297 views

Relationship between full duplex and speed

Full-duplex data transmission means that data can be transmitted in both directions on a signal carrier at the same time. but my question is if we have an interface with 100Mb speed and full-duplex ...
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Bandwidth limit between CPE and Provider Equipment

I have 4 different WAN links for redundancy one of them is 15mbps MPLS and the other ones are 30mbps Internet , 50 mbps Internet and 10 mbps MPLS , the way that it is set up is that we have load ...
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1 answer
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Can't access services on my other IP on same network interface GNS3 and Host [duplicate]

I have one physical NIC that is assigned an IP address (10.14.255.240). Inside of GNS3 network simulation tool, I also have a another 'virtual' interface with another ip address (10.14.255.245). Both ...
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1 vote
1 answer
637 views

Why a NIC in promiscuous mode and not will impact the capture packages?

I have a question about network interface Promiscuous mode, A NIC in promiscuous mode can receive all data passing through it regardless of whether the destination address of the data is it. If the ...
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Brocade XMR randomly losing virtual interface IP address

We have a pair of XMR routers configured 100+ VLANs running VSRP downstream and BGP upstream. At random times, the IP information is deleted and I have to go in and reset it. Each VLAN config looks ...
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Static IP assignment 3750X - DHCP Override

I have a 3750X that I am running some testing with. I have a VLAN interface that is using 10.10.10.254/21 as it's primary IP and 192.168.10.254/24 as it's secondary IP. See below: interface Vlan10 ...
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3 votes
1 answer
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Switching interface VLAN ID Mid-Production

I was wondering if there was a way to switch out the VLAN ID from VLAN1 to VLAN10 without impacting the connectivity of the end users? Can I simply copy and paste from one interface VLAN to another? ...
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2 votes
2 answers
7k views

What is the purpose of a switch routed port?

From my Cisco CCNA documentation: Routed ports are used for point-to-point links. Connecting WAN routers and security devices are examples of the use of routed ports. In a switched network, ...
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4 votes
2 answers
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Serial interfaces of router are used nowadays?

I've heard the use of serial interfaces of router is not so common in the current network environment. But in some exams like CCNA, you can still see questions including the knowledge of serial ...
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4 votes
3 answers
1k views

JunOS, access mode interface asks for a vlan

I'm kinda new to networking so I'm going to do my best to try explain my issue. The issue that I have is that I want to delete all default configuration for my xe interface. Current configuration: ...
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5 votes
2 answers
2k views

What's the `line protocol` and `Link`?

When I show a switch interface information, there are line protocol and Link: Switch-A(config-if)# show interface gigabitethernet 0/3 Gi0/3 up, line protocol is up (connected) Bridge Port Type: ...
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1 vote
2 answers
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Configuring routers on Cisco

If I have three routers R1, R2, and R3 that are interlinked, then when configuring, do I have to give the command: description Link to R2 description Link to R3 when configuring R1?
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4 votes
1 answer
427 views

Which physical interface would be used to send/receive packets intended for a loopback interface?

Let us say, I have configured the managed router with a loopback addresses - Interface IP-Address OK? Method Status Protocol GigabitEthernet0/0 ...
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2 answers
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Cisco Catalyst pseudo interface?

I think I remember reading somewhere that you could have multiple VLANs assigned to a single interface by way of a pseudo interface. Googling with that vocabulary doesn't return proper results though, ...
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4 votes
2 answers
2k views

Cisco ASA 5585X Internal-Data0/1 interface errors

I have noticed on Cisco ASA 5585 (SSP-20) interface error counter going up specially overrun but so far we haven't seen any production impact or issue, error rate is low so its not noticable but would ...
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3 votes
1 answer
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Is a network interface supposed to have no more than one MAC address?

Is a network interface supposed to have no more than one MAC address? Since a network interface is free to have more than one IP addresses, is IP address a way of multiplexing MAC address, if a ...
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3 votes
2 answers
367 views

Do the concepts of IP address and network interface not belong to the same layer?

https://unix.stackexchange.com/a/508065/674 You are confusing the device driver layers and the IP layers of the stack. At the IP layer, 127.0.0.1 is just another IP address and treated the ...
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2 votes
1 answer
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What can an IP address be assigned to?

What can an IP address be assigned to? A network interface, which is what I thought originally. (I seem to hear a network interface can have multiple IP addresses assigned to it, and if it is true, ...
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0 votes
1 answer
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Can more than one IP addresses be assigned to the same network interface?

Can more than one IP addresses be assigned to the same network interface? Is it correct that a network interface can be a physical one or a virtual one? Thanks.
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2 votes
2 answers
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Junos[MX]: How to show VPLS instance associated with given subinterface

Suppose I have a subinterface with Vlan-vpls encapsulation, like this one: admin@router> show configuration interfaces ge-2/1/1 flexible-vlan-tagging; encapsulation flexible-ethernet-services; ...
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1 vote
2 answers
343 views

Get DHCP IP with subinterface

Router0 has 1 subinterface on gi0/0 and can't get a ip trough dhcp. Is there something I forgot? The configs: Router0(got no ip from dhcp): interface GigabitEthernet0/0 ip address dhcp duplex ...
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3 votes
1 answer
106 views

DHCP Broadcast on SVI

Think of a dhcp broadcast going through multiple switches. What happens to that broadcast when it reaches the vlan interface (svi)?
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4 votes
3 answers
511 views

Mgmt Vlan vs other SVI s

Think of a layer 3 switch. Assume that we have a management vlan and a mgmt vlan interface. And we have other svi's on the switch. The question is this. I know that mgmt vlan is for telnet/ssh, simply ...
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2 votes
1 answer
178 views

Wireless Controller 5520 Creating a dynamic interface

I'm hoping to determine the least intrusive way to configuring my WLC. I am working through the GUI interface and have created a new dynamic interface [Controller-> Interfaces] When I went to ...
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