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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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Dhcp relay on backbone [on hold]

I'm configuring a backbone. I have a dhcp server and i need to use dhcp relay. Do i write the relay's ip adress under the vlan or the interface vlan? Is there a difference between these two situations(...
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2answers
49 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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2answers
86 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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29 views

Why does my 1921 Router not bring up its interfaces?

I have the 'no shut' command entered on both interfaces. They work when I enter the command. I copy run start 'wr' Power was cycled for the Router, Switch (3560x-24), Cable modem and AP. They were ...
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1answer
41 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
288 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
37 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
19 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
35 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
56 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
37 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
95 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
30 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
566 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
902 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
38 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
158 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
22 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
119 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
36 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
217 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
76 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
68 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
31 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
318 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
99 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
142 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 ...
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3answers
1k views

How not to route on a Cisco router

So we have a router, with a switch card interface, 8 ports Say I have 4 VLANs (A,B,C,D) on it, with 2 switch ports in each. Each VLAN (i.e. all ports) can communicate with each other, because ...
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1answer
35 views

My interface do not have a IP address in a segment, but I can ping the IPs of it

You see, in my local Mac's network interface there is no 172.18.1.*: $ ifconfig lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384 options=1203<RXCSUM,TXCSUM,TXSTATUS,SW_TIMESTAMP&...
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1answer
85 views

Network interface issues an ARP request to get the MAC address of an actively used gateway

My network interface actively uses a gateway to send IP packets to other networks. There is already an ARP entry in the cache for the IP/MAC association for the gateway. Is it normal that my network ...
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3answers
46 views

Interfaces named with `ge` represent what?

I see a information: Most interfaces are named according to: - Interface media type (ge, so, at, and so forth) ... I know the so represent SONET, at represnet ATM, but how about the ge ? if it ...
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2answers
87 views

Identify IP of the client causing high interface usage on uplink port

Background: We are observing a high interface load (spikes up to 1G) on a WAN (dedicated link) uplink port of a Cisco switch. How can we find the IP of the client that is causing this high load? I ...
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3answers
355 views

Empty mac address value [closed]

Is there some MAC address value, that can be used to denote that device does not have MAC set (something like 0.0.0.0 for IP).? I thought of ff:ff:ff:ff:ff:ff, but afraid that it could be meaningful ...
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2answers
1k views

Network Gateways vs Interfaces

When looking at the contents of a routing table section on the Wikipedia article on Routing Tables, it contains a table as an example of a routing table with two headings which have an unclear ...
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2answers
91 views

Why it is neccesary to assign IP adresses to interfaces?

I know this is a very very basic doubt, but never I thought of it in a deep perspective. For example, I am going to use the following scenario: You know that we usually use a /30 mask when you are ...
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1answer
287 views

Trunk on the outside ASA interface

I have a topology as in the picture. It is designed to be a factory network. 2 ASAs in a failover cluster border the whole LAN. And it is pretty much clear how to configure them: outside interface to ...
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1answer
89 views

Is TCP checksum verification also offloaded to NICs? [closed]

I understand that checksum calculation at the sender side is often offloaded to the NIC. Does this also happen for verification at the receiving end?
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1answer
2k views

Subnetting and switch configuration (CISCO Packet tracer)

I'd like to ask couple questions that I have about subnetting and switch configuration (more about latter). Currently, I have subnetted my network to be on IP 192.168.10.0/29 with subnet mask 255.255....
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1answer
413 views

GNS3 wic vs slot

can any one explain the difference between WIC vs Slot? plus I want to have more L3 links in GNS3 but I cannot have more than 4 on 3725 router. there are two built in plus i can add two NM-1FE-TX in ...
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1answer
142 views

EHWIC-1GE-SFP for Cisco 1941

I was able to configure the interface but only the GE port is working, not the SFP port. Did I miss something?
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2answers
430 views

Ping loopback without interface IP address

I have two routers attached directly and both of them has loopback address. The interface has no IP address, I have just connected R1 g0/0 to R5 g0/0. If I put IP address on the g0/0 interface of both ...
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1answer
1k views

“Gateway of last resort is not set” even though I have a default route to a tunnel interface

I work with Cisco CSRs. On all of my previous CSRs in AWS, I have the following: AWS-ENV-CSR-R1#sh run | in ip route ip route 0.0.0.0 0.0.0.0 Tunnel1 ip route 0.0.0.0 0.0.0.0 Tunnel2 2 AWS-ENV-CSR-...
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2answers
212 views

Physical / Virtual Interfaces.

Well, I know that's a simple question for the level of this forum, but yet, I didn't found anything on Google, at least not what I want. I'm studying for CCNA R&S and I just learned about ...
2
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1answer
153 views

Can I curl a Cisco sg300 switch to get running config, MAC address table, int des, etc.?

I'm auditing switch interface descriptions at work. I work nights and sometimes people during the day shut down their computers when they leave, so I don't see which computers are on interfaces when I'...
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2answers
42 views

What are parts of interface name called

Consider this interface name GigabitEthernet1/0/48 I know that GigabitEthernet is an interface type. What does 1, 0 and 48 stand for?
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2answers
1k views

Aruba OS equivalent for default interface

I need to reset or default an interface on an Aruba switch. This may be the same for HP procurve switches, but I am not sure. On Cisco, the command would be default interface in global config mode. Is ...
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2answers
283 views

Inter-vlan routing with unmanaged switch?

I have a Cisco 3650 with inter-vlan routing enabled. All vlans reach each other with no problems. The problem appeared when I connected an unmanaged switch to an interface on the cisco. I set up a ...
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2answers
1k views

Address of the router interface in subnetting [closed]

I've been given a Class C address, let's say 192.10.20.0. I have a topology of 4 routers, each with a serial connection to two of the other routers (like a square). To each router is connected two ...
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2answers
282 views

Can a broadcast storm do physical damage to computers and networking hardware?

We had a broadcast storm that went undiagnosed for several hours. After the problem switch was unplugged and traffic returned to normal, we had a handful of machines and switches that were broken. On ...
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1answer
660 views

Cisco 2811: VLANs, Subinterfaces, HWIC-4ESW

I asked a question not too many hours ago about multiple router interfaces on one network, and I think I have now established what I need to do, however I do not understand how to implement it. For ...