Questions tagged [interface]

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

Filter by
Sorted by
Tagged with
4
votes
2answers
8k 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 ...
-1
votes
3answers
2k 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 ...
1
vote
2answers
156 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 ...
2
votes
3answers
2k views

Cisco C3560CX Interface number/name question

The Cisco C3560CX's come in flavors that include 10gbs SFP+ ports (e.g. WS-C3560CX-12PD-S), and also less expensive ones that only do 1gbs SFP (e.g. WS-C3560CX-12TC-S). Documentation shows you can put ...
1
vote
2answers
139 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 ...
2
votes
3answers
572 views

Arista switches- Email alert if interface status changes

I'm looking to be notified of interface state changes on my Arista switches without my manual polling of the logs. For example, tailing var/log/messages, I might see something like: un 29 19:10:48 ...
2
votes
1answer
498 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 ...
1
vote
2answers
401 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 ...
0
votes
1answer
104 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?
2
votes
1answer
4k 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....
5
votes
2answers
697 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 ...
1
vote
1answer
1k 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 ...
5
votes
4answers
9k views

Multiple IP Addresses on VLAN Interface (SVI)

Let's say that there is a SVI for VLAN 100 and it's been assigned the first usable IP address in subnet 192.168.1.0/24. There is a host on VLAN 100 with an IP address of 192.168.1.130. We need to ...
1
vote
1answer
3k 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 ...
2
votes
2answers
1k 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 ...
1
vote
1answer
2k 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-...
1
vote
1answer
62 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 ...
2
votes
1answer
245 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'...
1
vote
2answers
49 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?
2
votes
1answer
88 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
2answers
4k 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 ...
0
votes
2answers
3k 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 ...
3
votes
2answers
1k views

Cisco: Two interfaces on one network

I'm a newbie to Cisco Equipment and IOS, but got myself a Cisco 2811 and have been playing with it and getting to grips with the basics quite happily. One problem i'm having is trying to get two ...
1
vote
1answer
2k 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 ...
2
votes
2answers
496 views

Manually set combo interface for RJ45 Cisco 3560-CG Series

I have a Cisco Catalyst 3560-CG that has two combo ports with SFP and RJ45 each. Is it possible to manually set the combo port to use the RJ45 only? If so, how is it done? I am troubleshooting a ...
1
vote
1answer
45 views

How to know which IPv6 interface will be chosen by the router?

I would like to know how does the kernel decide through which interface it sends data to some IPv6 address, how is the calculation done based on the routing table information: destination, gateway and ...
0
votes
1answer
57 views

How to assign IPs in server interfaces when connected to two similar routers [closed]

I need to connect two similar routers with the IPs 192.160.2.4/24 and 192.160.2.6/24 (in the same 192.160.2.0/24 network) to 2 server interfaces (ports) in the same server as shown in the image. ...
0
votes
2answers
430 views

Physical interface as switch port and VLAN interface as layer 3 [closed]

In most of large ISP networks, physical interfaces are used as switch ports (layer 2 port) and VLAN interfaces are used as layer 3. Could you please explain what is the main purpose to use like this?
1
vote
2answers
523 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 , ...
1
vote
0answers
757 views

Interface is up, but wan interface ip not pinging?

I have Juniper ACX-2200 router , i have assigned an ip address to the vlan tagged to ge-0/1/2 interface , and interface status is up, but self wan interface ip not pinging , ip won't even show up in ...
7
votes
2answers
69k 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
vote
1answer
1k views

ARP requests and multiple interfaces

Suppose a device has both ethernet and wireless interfaces enabled and active. Is it correct that ARP requests from one (e.g., ethernet) cannot reach the other (e.g., wireless) unless a Proxy ARP is ...
1
vote
1answer
117 views

what type of fiber SFP for cisco 6500 Gbic module

I have an old 6500 with 6516a GBIC module (picture) and im planning to do some testing with it. I've already looked over Cisco's product page, and im still having a hard time identifying what SFP ...
1
vote
2answers
7k views

What are "Excess Defer Frames" on a show interface gix/x/x controller output?

I have a switch that is counting "output errors". A "show interface gi1/0/46 controller" shows up "2963657 Excess Defer frames" but I really can't find any documentation about "excess defer frames". ...
1
vote
1answer
899 views

Diifference between sfp/sfp+ ports and unified ports

there is something I don't understand. Some switches have SFP ports, it means that you can connect fiber or rj-45 cables I believe? Some switches like Nexus 5600 have unified ports. So they can ...
1
vote
1answer
4k views

Issues trunking VLANs from pfSense to Cisco switch

I am currently using an old desktop with a dual port PCI NIC as a pfSense router. Interface em0 is assigned to the WAN interface, and em1 is assigned to the LAN interface, as well as 3 VLAN interfaces ...
1
vote
1answer
1k views

TACACS: multiple source interfaces

I have a Cisco router connected to a TACACS server via two interfaces. As a prerrequisite, no loopback should be set on the router. My question is: Is it possible to set these two interfaces as ...
1
vote
1answer
780 views

VLAN trunk between Single Port Machine to Switch

i have this setup which is a bit low end because i ran out of test server to test so i'm just doing what i can to attain target setup. Normally i would use a blade or rack type server. So my setup ...
0
votes
1answer
730 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 ...
1
vote
1answer
2k views

debugging arp requests over vlan

We have a chain of switches configured for vlan 13, let's call them switch1, switch2 and switch3 No, somewhere on this chain the arp requests get lost. I can run tcpdump on these switches. Running ...
18
votes
7answers
60k views

Cisco command to show which interfaces an ACL is applied to

For Cisco routers and switches, is there a show command, or something similar, that will display what physical and logical interfaces an ACL is implemented on and what direction it is applied in? I ...
4
votes
3answers
10k 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
votes
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
votes
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
votes
1answer
64 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)
1
vote
1answer
12k 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/...
5
votes
1answer
19k 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 ...
3
votes
2answers
608 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,...
2
votes
1answer
339 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
vote
0answers
166 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, ...