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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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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22 views

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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2answers
85 views

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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51 views

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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Cisco Router Interface Connection Problems

I am new to networking and am configuring, I am trying to setup my connections in packet tracers for 3 different routers to talk to each other over Serial ports as attached. However, I did notice ...
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1answer
53 views

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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1answer
472 views

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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2answers
45 views

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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131 views

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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27 views

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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1answer
383 views

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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2answers
30 views

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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2answers
126 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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1answer
30 views

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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1answer
33 views

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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1answer
240 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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54 views

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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1answer
57 views

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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1answer
121 views

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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1answer
2k 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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2answers
119 views

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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3answers
487 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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771 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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1answer
44 views

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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1answer
341 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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2answers
105 views

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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1k 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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1answer
186 views

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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2answers
338 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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1answer
78 views

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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1answer
35 views

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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2answers
191 views

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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2answers
193 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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1answer
93 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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2answers
302 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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1answer
93 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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3answers
704 views

What is responsible for dropping Layer 2 frames that's not addressed to it?

It's my understanding that if a network interface card (NIC) receives a Layer 1 packet, it will extract the Layer 2 frame from it, checks its destination MAC address, and if it is not addressed to it (...
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2answers
1k views

How does a router know the MTU of a network?

I've done several exercises where you're given the MTU of a net or subnet, but I wonder how routers know the MTU of the nets they're connected. I've learnt that in OSPF protocol this information is ...
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1answer
95 views

Can not add a Physical port into LAG

Using SuperMicro network module, which related to Intel SDN product, the command PDF . and the Web GUI manual. there I have qe57, qe61, qe65, qe69 four upstream ports, I want to aggregate them to one ...
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1answer
593 views

Urgent: how to configure different interface using same ip subnet in asa 5506?

Scenario is in old asa firewall 5505 I have switch port access vlan command in different interface. Just like below: interface Ethernet0/0 ! interface Ethernet0/1 switchport access vlan 2 ! ...
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1answer
25 views

i cant configure the ip adress and subnetmask ,i only have one router “1941” and 2 pc's

the command line is this : Router0(config-if)#ip adress 192.168.1.1 255.255.255.0 the error message is : % Invalid input detected at '^' marker.
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1answer
473 views

How to create interfaces for CSR 1000v for GRE tunnels?

Well, my idea is to connect to 4 CSR 1000v routers in different VPC (without VPC peering). I've basically finished with everything with the pre-configuration creating VPCs, subnets IGW, modifying ...
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1answer
66 views

Multiple Networks on Sonicwall with no access to cisco firewall

The issue im having is that i have 2 networks with 2 internet connections. We now all of a sudden have a POS system handling our network. This system blocks our email and a bunch of pages we use. They ...
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2answers
843 views

How can two interface communicate between them with different subnet

R1 and R2 are connected with serial cable interface but both of them having different subnet and i know they will not communicate so what are other options two communicate between them without the ...
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1answer
204 views

What's the relationship of a Router with its loopback interface in logic?

I have a Router1 with a loopback 0 connected to the Router2: the interface brief is bellow: Router1>show ip interface brief Interface IP-Address OK? Method Status ...
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1answer
225 views

How to use“ Multimode SFP GLC SX MMD” in Cisco Catalyst 2960 S connected LAN and single mode OFC network

We have single mode OFC network and CAT 6 CAT5 LAN with ethernet and gigabit Ethernet switches and ordered for "GE SFP, LC CONNECTOR LX/LH TRANSCEIVER FOR SINGLE MODE FIBER OF CISCO CATALYST 2960 S" ...
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1answer
44 views

Network Security Tunnel

In the Tunnel Interface, when I edit the tunnel information, it shows: Attributes Values Tunnel Source IF10 Tunnel Destination 1.0.0.1 Tunnel Mode GRE What does IF10 ...
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2answers
1k views

How to assign all interfaces in one router to OSPF backbone area?

Is there any command to assign all interfaces in router (CISCO 2691) to OSPF backbone area? I was using this command for each interface. network address wildcard-mask area area-id Where wildcard ...
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1answer
678 views

Can not create sub-interface like `interface gigabitEthernet 2/1.100`

I follow a tutorial, there shows the method of create sub-interface: but in my actual situation, I can not do this: Router(config)#interface gigabitEthernet 2/1.100 ...
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2answers
744 views

Why the Cisco Router's loopback interface can not be showed up by default?

By default, why the Cisco Router's loopback interface can not be showed up? Router#show ip interface brief Interface IP-Address OK? Method Status Protocol ...