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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6answers
6k views

Why do I need to specify a subnet mask on interface?

When assigning an IP address to an interface, why do I need to specify a subnet mask? I understand the purpose of subnet masks in a routing table for example (to specify a range of IP addresses as ...
1
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1answer
44 views

How do i set this ACL on the router

I was told in a previous answer to use ip access-list extended TEST deny ip host <PC0 address> host <PC5 address> permit ip any any But, whats the command to set it on the router ...
1
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1answer
408 views

how to connect 2 routers to communicate?

What cable connects routers to communicate ? I am using Packet Tracer Simulator, and I connected 2 routers using a DTE connector. After doing this, I am unable to ping between the 2 routers. Is using ...
2
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2answers
7k views

what are input errors on the CISCO switch?

In my topology, I have connected spirent - traffic generator to MRV switch ( L1 switch) and then connected to CISCO switch. I am seeing some input errors on this interface. What does it mean? Does it ...
1
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2answers
276 views

Required VLAN overlapping allowed?

I configured the switch for two VLANs, as below: Projects-3560-(config)#int vlan11 Projects-3560-(config-if)#ip address 10.110.1.1 255.255.255.0 Projects-3560-(config)#int vlan10 Projects-3560-(...
6
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4answers
70k views

What is the difference between WAN and LAN ports?

I was looking some routers and I noticed that in some of them there is a distinction between WAN and LAN ports? The WAN ports is to connect an access point and LAN ports to connect a switch or a PC?
2
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2answers
2k views

What are the most common scenarios in which the 'loopback interface' on a router is used?

I was studying about CISCO routers and we learned that every router has a LOOPBACK interface. How and when are those interfaces used? We never used it though in our configurations.
2
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1answer
1k views

admin state Vs link state from a network engineer stand point

On a network switch, if the admin state is made "UP" by using a "no shutdown" on that physical interface then it remains "UP" what so ever until the port is configured as "shutdown". This is the ...
2
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1answer
19k views

How to know the interface utilization on a Cisco switch?

I would like to confirm. Is the above below information in bold sufficient to know the utilization of my interface in percentage? Switch#sho int fa0/8 FastEthernet0/8 is up, line protocol is up (...
4
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3answers
9k views

interface down time summary

bar show interface link is there an alternative (pretty) way to display a summary of link last in use. Goal is to get a view of how long a link has been unused. Something along the lines of: show ...
2
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1answer
55 views

cisco Output Queue Droppped on down interface

what does it mean if an interface is reported down but there are drops on the interface? show interface X displayed: Total output drops: N line protocol is down (notc)
0
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1answer
729 views

Configuration interface VLAN hp switch [closed]

my company purchased a new switch brand HP and I created two VLANs on it. VLAN 2 is for the ports 47 and 49 that provide access to internet through a fiber cable and other VLAN 1, which is for the ...
6
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2answers
1k views

Why is Cisco enforcing X:X:X:X::X for link-local addresses when the standard says FE80:/10?

This document shows that you can use one of these options: interface type/number ipv6 address ipv6-prefix/prefix-length eui-64 ipv6 address ipv6-prefix/prefix-length link-local <------...
1
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3answers
133 views

Gigabit NIC stuck on 100mbs

My main problem started when i installed 4 gigabit NIC into my computer. The 4 NIC are connected to GB linksys switches, each in different location,1 of the 4 gives GB and the others are stuck on 100 ...
2
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1answer
2k views

How exactly is “input rate” calculated in IOS “sh int” output?

Cisco IOS routers display input and output bps and pps values for load-interval time period in sh int output. For example here is load-interval set to 30 seconds: C1921#sh int Gi0/1 | i rate 30 ...
1
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1answer
8k views

Overlapping with Serial0/0/0

I have tried configuring the serial interfaces and it is working for two devices which is my HQ1 and HQ2: HQ1 - IP address 120.244.121.136 on Serial0/0/0 HQ2 - IP address 120.244.121.139 on Serial0/0/...
4
votes
1answer
17k views

What is “usec” and “delay” a measurement of?

The term usec appears in the delay field of the show interface command on a router: Router# show interfaces fastethernet 0 Fast Ethernet0 is up, line protocol is up Hardware is DEC21140, address ...
1
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1answer
2k views

Multi-area OSPF, Use Wildcard/Subnet IP address OR Quad zero and interface IP address?

I am trying to configure multi area OSPF on several routers (in packet tracer) to a switched core area 0. If I understand correctly, I could either choose to configure OSPF using router interface IP ...
7
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4answers
4k views

Why do I get “% Warning: use /31 mask on non point-to-point interface cautiously” when I use a /31 subnet mask?

Why do I get % Warning: use /31 mask on non point-to-point interface cautiously when I use a /31 subnet mask over Ethernet, and why am I not able to ping from R1 to R2 when both the interfaces have ...
3
votes
1answer
628 views

Does traceroute show the IP address of the entry port? or exit port?

Does traceroute show the IP address of the entry port? or exit port? For example, if there is an intermediary router in the path with 198.28.56.18 facing the source (entry port), and 65.86.24.136 ...
2
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1answer
311 views

Linux routing: routing between 2 local interfaces depends on source address? [closed]

The setup is this: The linux system (debian 7 as a VBox guest) has the following interfaces: $ ip addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/...
1
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0answers
154 views

Basic Interface MTU Setting [closed]

I would like some clarification on the MTU setting on an interface and the size attribute for ICMP. I have two routers connected directly with an MTU of 1500 set on both sides. There is no dot1q, ...
2
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1answer
68 views

Why switch (2950) port configuration is needed when NIC adapter is configuired?

I have two Cisco 2950 switches connected with a Dell 7810 machine to provide network redundancy. The machine is equipped with one built in (On Mother Board) Ethernet port and with a dual port NIC “...
1
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1answer
59 views

Using different NIC vendors on a LAN - does it make a difference?

I was reading up on network interface cards and came across this statement: "Avoid mixing network adapters from different vendors on the same LAN. Although all may follow a standard, implementation ...
0
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2answers
305 views

I'm confused about ethernet interfaces (eth/in, eth/out, eth/local)

I'm using an Edgemax router (EdgeOs), and even after having read posts and checked internet pages, I'm still very confused about which of my ethernet interfaces are communicating with what. My LAN is ...
5
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5answers
13k views

How many IP addresses can a device or an interface possess?

Can one IP address be assigned to more then one device or interface? In which situations may this happen? Can one device or interface posses more than one IP address?
2
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2answers
1k views

Why use two NICs, one external facing and the other internal facing? [closed]

As the question implies, why use two NICs, one external facing and the other internal facing when one would suffice for both functions using NAT.
2
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1answer
87 views

Can I use a router which has just one working interface? [closed]

I have a Mikrotik RB532 router with three Ethernet ports. One of the ports supports PoE and the other two don't. The main point is that LAN2 and LAN3 interfaces are broken. Can the device still be ...
2
votes
1answer
463 views

Showing the current intput/output rate on a cisco device

Is there a way to check the current interface output/input rate on Cisco devices? the interface statistics only give the average over 5 minutes, and monitoring the interface seems to have a very long ...
1
vote
1answer
2k views

How many network interface can a network interface controller have?

If I am correct, a network interface is the interface between a network interface controller and a network. If I am not correct, please let me know. How many network interface can a network ...
1
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2answers
985 views

Interface on ASA 5525 cannot turn up/up

The interface is connected to a switch and has the no shutdown command applied. The interface at the switch is already up/up, but ASA's interface is still down/down. Another ASA also has the same ...
3
votes
1answer
194 views

OM3 optical fiber 850 nm compatibility with 10GBASE-LRM

I have Cisco equipement with "XENPAK-10GB-LRM" and Optical Fiber Type OM3 wavelength 850 nm. As the LRM interface works at 1310 nm, will it work with this type of Fiber.
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2answers
486 views

problem with inter vlan routing with ip helper

here i used the recommendations of making the DHCP server an external server and just use the command IP helper X.X.X.X in cisco 4500X under each interface vlan to relay DHCP to hosts in this vlan , ...
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0answers
2k views

Get interface input/output rate statistics over SNMP from Huawei switch

We need to monitor the download/upload bandwidth on interfaces on Huawei S5300 switches, and we need to do it with a specific monitoring system. This system can get information from a switch using ...
3
votes
2answers
7k views

Network Daughter Card vs Network Interface Card

I've noticed that when customizing a server for Dell you have the option to select between "Network Daughter Cards" and "Network Interface Cards", as well as a number of others. I've looked up the ...
2
votes
2answers
19k views

How do i factory reset a Allied Telesyn AT-9924t?

I have connected to the switch from my Win7 computer with the following equipment. (the blue cable isnt the exact one, but nearly the same) When i restart the switch while connected with Putty or ...
1
vote
2answers
319 views

Cisco disables port on switch when configures linux bridge

I have a CentOS server plugged into a Cisco 3048. I use nm-connection-editor to configure a virtual bridge interface, like I've done a thousand times before. Every time I enable the bridge, the ...
5
votes
4answers
7k views

DLink switch loses configuration on power off!

We just bought a DGS-1210-28P smart switch, it is my first experience with a business class switch, however I found a pretty weird behavior. The switch loses all of its configurations, even management ...
1
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1answer
6k views

I disabled an interface in vyatta, how do I enable it?

I entered set interfaces eth0 disabled which worked. show interfaces shows that the interface is administratively down. However I can figure out how to bring it back up.
2
votes
1answer
513 views

Dell 6248P Powerconnect Switch - Routing IP Configuration - What is it for?

This is a rather simple question but I cannot seem to find a resource that explains what this feature is for (without it simply saying "this is to configure an IP interface"....very helpful) Can ...
2
votes
2answers
11k views

SonicWall : Blocking Access Between Different Subnets or Interfaces

I have two interfaces on NSA 220 configured as follows Real interface X2 192.168.1.1/24 LAN Zone Virtual interface X2:V1 192.168.2.1/24 VLAN ID 100 LAN Zone In this configuration computers in ...
6
votes
1answer
1k views

Cisco ASA startup-config command ordering for sub-interfaces

In relation to another question on this forum, Moving interface names on a Cisco ASA while maintaining the rest of the configuration in place, I modified the startup-config on my Cisco ASA 5525-X from....
2
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2answers
11k views

Subnetting Question [closed]

Consider a router that interconnects three subnets: Subnet1, Subnet2, and Subnet3. Suppose all of the interfaces in each of these three subnets are required to have the prefix 223.1.17/24. Also ...
1
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2answers
94 views

Is an interface's limit independent of input/output?

Suppose I have a 10 Gbps interface in a router. Does that mean the maximum amount of traffic I can send through the interface will be some combination of input/output rates up to 10 Gbps, or can I ...
3
votes
2answers
571 views

Juniper SSG and multiple interfaces

Okay guys I have a conundrum on my network, I do not know how it is working, I just know it does. I have a Juniper SSG firewall with 3 different ISPs. I have traffic coming in through the 3 interfaces,...
1
vote
1answer
4k views

How do testers (i.e. Fluke) get the port they're connected to?

At work I've been tasked to create a program that acts similar to Fluke testing devices (such as LinkRunners) but will be much more extensive and specific to our needs. One of the capabilities that ...
10
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4answers
155k views

What can cause “FastEthernet is up, line protocol is down” on a Cisco Switch?

I wonder what can cause the first line output of the command show interfaces to be: FastEthernet is up, line protocol is down. In other words, Is the cable that is connected to the local interface, ...
7
votes
2answers
64k views

Difference between CRC and input errors - show interface

The command "show interface fa0/1" prints the following output: What is the difference between "CRC" and "input errors"? CRC errors confirms that a frame error has occured, but what about "input ...
-1
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1answer
599 views

How port, channel and interface are working together?

I do know about Physical port but a little knowledge about channel and interface, can any one explain how these 3 work simultaneously, i am not getting proper idea and from cisco i got to know about ...
5
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1answer
3k views

Routing on firewall vs L3 switches

So we have an environment with several VLANs connected to a FortiNet firewall using multiple interfaces trunked back to our L3 Dell PowerConnect 6248P switches. Currently the FortiNet is setup to do ...