Cisco is a major provider of switches and routers to most medium and large companies. Cisco devices often run IOS or NX-OS. This is a generic tag to be used when no more specific tags are available. See the partial list of tags in the full Tag Wiki.

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15
votes
2answers
1k views

What is this item that came with my Cisco switch?

We just received a new Cisco Catalyst 2960, and in the box came an item we've never seen before. Interestingly enough, the documentation shows an image of the object, but it is not listed anywhere ...
14
votes
5answers
1k views

Are Cisco admins expected to understand classful networks?

While studying for the CCENT exam, my reference materials have made an alarming number of references to class A/B/C networks. Thankfully they just treat Class A/B/C as shorthand for /8, /16, and /24 ...
14
votes
5answers
4k views

ARP broadcast flooding network and high cpu usage

Hoping someone here might have some insight to the issue we are facing. Currently we have Cisco TAC looking at the case but they are struggling to find the root cause. Although the title mentions ARP ...
13
votes
5answers
1k views

IPv6: How to start? (ISP perspective)

In our company we have a range of /21 (2048) IPv4 public addresses. We have a bunch of Cisco routers and servers. How to get started with IPv6? What can we do to provide internet to our clients with ...
12
votes
5answers
14k views

Code to generate Cisco “secret” password hashes?

Does anyone have a pointer to code (or just the algorithm) that Cisco uses to generate their password hashes for things like "enable secret"? I'm not trying to break into anything; I'm trying to ...
11
votes
8answers
27k views

Blocking Facebook and Myspace by IP address

I'm having some trouble making a Cisco ASA device block certain social networking sites which have become time sinks in our office. This question is really in two parts: Is there a reliable way to ...
11
votes
2answers
781 views

What's the protocol-level difference between IPSec and “Cisco IPSec”?

Most VPN clients distinguish between IPSec and "Cisco IPSec." For example, (Apple's) iOS treats them as essentially separate things. But I can't find any explanation of what the protocol-level ...
10
votes
9answers
2k views

Why buy high end hardware firewalls?

There exist firewalls from Juniper and Cisco that cost more than a house. So I wonder: what does one get from a $10.000+ firewall compared to an 2U server with 4x 10Gbit network cards running e.g. ...
10
votes
2answers
177 views

How to safely install a new IOS image on a Cisco device when the installed flash memory size isn't enough for two of them?

Today I was updating IOS on a Cisco 877 router, and a problem came up: the installed flash memory wasn't enough to hold both the old and the new IOS images, so the new one couldn't be uploaded unless ...
10
votes
3answers
511 views

Cisco ASA and multiple VLANs

I currently manage 6 Cisco ASA devices (2 pairs of 5510s and 1 pair of 5550s). They all work quite nicely and are stable so this is more of a best-practice advice question rather then "OMG it's ...
9
votes
3answers
3k views

Why is my router CPU at 40% when no processes use more than 2%?

I have a problem, I have a Cisco 1841 running Cisco IOS 15, and I get strange behavior. The CPU usage is shown as 40%, but there is no processes that is using this much CPU power. Here is an ...
9
votes
2answers
3k views

Is my Cisco switch port bad?

I've been chasing a packet-loss and network stability issue for a handful of end-users on an internal network for the past few days... These issues surfaced last week, however the location was struck ...
9
votes
3answers
214 views

Native VLAN mismatch and missing VLAN?

I'm trying to wrap my head around what exactly is going on here with a new site's configuration of their networking stack. This particular piece I am working is pretty simple but I having a hard time ...
9
votes
6answers
1k views

What is the best solution for traffic control in a large system (ca. 2000 users)?

following situation: We're a group of students administering the internet connection for the local resident halls, with a total of about 2000 end users. We have a traffic point system, every MB down- ...
9
votes
5answers
1k views

Spanning Tree Setup

I understand the basics of spanning tree, but that's about it. I'm hoping that someone can tell me if this will work as I want it to. I've got two Cisco ACE load ballancers setup for redundancy. ...
8
votes
3answers
398 views

Cut network cables in Cisco 2960 PoE

We've a Cisco 2960e that services our VoIP phones and other things. I inherited it. The question I have is the cut cables: there are about four network connectors that are cut about 1cm away from the ...
8
votes
7answers
2k views

Are VLANs necessary for my environment?

Greetings. I'm the new network manager for a school. I've inherited an environment made up of several Windows servers, about 100 Windows clients, ten printers, one Cisco router, six Cisco switches, ...
8
votes
1answer
5k views

Authenticate Linux sshd with TACACS+ (Cisco ACS)

Our network engineering team uses multiple linux servers for syslog collection, configuration backups, tftp, etc... We want to use TACACS+ on a Cisco ACS machine as our central authentication server ...
8
votes
4answers
3k views

New network design from a noob. VLANS, IP's, hardware, etc. Any comments please

I’m currently planning a large network infrastructure for a University in Ethiopia and would like people’s comments on my planning. Please bear in mind I have never done networking before. The campus ...
8
votes
2answers
1k views

Smart card authentication to a Cisco switch?

We have our Cisco network devices configured to authenticate network administrators using their domain accounts via RADIUS running on a Windows 2008R2 server with the network protection role. This ...
7
votes
4answers
2k views

Can a Cisco 3550 be used as router?

Very recently I picked up a Cisco 3550 just to play around with networking and to familiarize myself with Cisco's command line configuration due to the fact that I will be working an electrical ...
7
votes
10answers
36k views

Identify machines connected to switch

Our company recently closed down half our office space, which was not being used. We gave back the unused space to the building management and had it walled off. Prior to us closing it off, I jotted ...
7
votes
3answers
11k views

How do I reach my internal server on the external IP?

We are trying to configure our Cisco 5505, and it has been done through ASDM. There is one big problem that we're not able to solve, and that's when you go from inside to outside and back in again. ...
7
votes
3answers
6k views

How to obtain Cisco IOS firmware?

Quick and simple question, but I've not been able to find an answer around. I have a Cisco ADSL router (model 877). I don't have any Cisco support contract. How can I obtain an updated firmware for ...
7
votes
6answers
5k views

Cisco VPN Client for Windows

is there any Free Cisco VPN Client software for Windows ?
7
votes
6answers
549 views

Cisco router for educational purposes

I want to buy a Cisco router to use on my home network. I'm just hoping to get a unit that is not too old and is not a SOHO model. I want to run the latest Cisco OS just to learn how Cisco does ...
7
votes
8answers
8k views

Alternative Cisco VPN clients for Windows XP

I'm considering investing in a Cisco ASA5505. As Cisco's own VPN client requires a service subscription, which I am trying to do without, are there any free or low-cost ipsec VPN clients that will ...
7
votes
4answers
1k views

How do you document your Cisco configurations?

How do you document your Cisco configurations? How much / what kind of information do you include in the description field (connects to, circuit ID, device information, etc.)? Do you use any ...
7
votes
1answer
2k views

High latency/drops between Cisco switches in two locations. How to troubleshoot?

I'm receiving user complaints about poor network application performance between two parts of a large warehouse facility. The software is a curses-based terminal application running on a Linux server. ...
7
votes
3answers
3k views

Cisco and Linux and Vlans

I appear to have some fundamental misunderstanding of how VLANs work on Linux, and I'm hoping the good people here can educate me. Cast: One Cisco 3560, one VLAN, and one Linux box [1]. Cisco ...
7
votes
2answers
16k views

Connect to Cisco ASA 8.2 VPN with Android 2.1 L2TP/IPsec?

I am trying to configure my Cisco ASA 5510 running software version 8.2 to allow my Droid X to connect via L2TP/IPSec VPN. I have configured the DefaultRAGroup like so: tunnel-group DefaultRAGroup ...
6
votes
4answers
1k views

Is Selling Old Cisco Routers a Security Issue?

I'm a system admin but I'm not Cisco certified and I'm not a network engineer. Basically I only use switches/routers/modems with a GUI. I've inherited a pile of old Cisco routers that are not in use ...
6
votes
2answers
2k views

pfSense Firewall or Linksys/Cisco router for small offices

I'm about to start switching some networks around for multiple small offices. Each office has about 10 to 15 users and 10 to 15 computers. Each office has a spread of generic routers and access ...
6
votes
1answer
253 views

How do I configure NAT rules when using ASA IP-SLA when leveraging post-ASA-8.3 NAT syntax?

We are currently running ASA9 at a location with redundant ip connectivity. We'd love to configure ip sla so that internet access survives a single carrier outage. I'm aware of the ip sla commands, ...
6
votes
4answers
1k views

Cisco IOS QoS prioritize SSH but not SCP

How can I prioritize ssh traffic to ensure low-latency but throttle SCP file transfers? I'm looking for a solution that is not host specific so I don't have to add lists of IP addresses. Thanks!
6
votes
2answers
2k views

DMZ subnet: to NAT or not to NAT?

I'm looking at setting up a DMZ behind a Cisco ASA that will contain a large number of HTTP front-end load balancers and SSL offload services - over 100 IPs, concentrated on a smaller number of hosts. ...
6
votes
3answers
452 views

Mixing SFP's with different speeds

I need to install new SFP's in a location; however, I need them to connect to existing switches and I'm not sure what SFP type they are. All I know is I've got MM Fiber. If I installed Cisco ...
6
votes
7answers
928 views

Are there any good free Cisco router simulators out there?

I'm just starting some Cisco training and I would like to know if there are any freely available simulators available.
6
votes
2answers
2k views

HP to Cisco spanning tree root flapping

Per a recent question I recently configured both my HP (2x 2900) and Cisco (1x 3750) hardware to use MSTP for interoperability. I thought this was functional until I applied the change to the third ...
6
votes
1answer
361 views

Cisco FWSM -> ASA upgrade broke our mail server

We send mail with unicode asian characters to our mail server on the other side of our WAN... immediately after upgrading from a FWSM running 2.3(2) to an ASA5550 running 8.2(5), we saw failures on ...
6
votes
1answer
2k views

Is bonding mode=5 a solution against MAC flapping?

There is two are interconnected Cisco WS-2950T. By the one GBIC port on first switch connected a first NIC of bonding interface, and by the one GBIC port on second switch connected a second NIC of ...
6
votes
4answers
514 views

How to buy from Cisco and/or Juniper when you're a small company? [closed]

I find it quite difficult to buy from Cisco and Juniper : no price-tags can be found on their websites, let alone buy-online capabilities a "buy cisco" google-search will mostly return websites ...
6
votes
3answers
143 views

Cisco Dot1x Port Authentication - VLAN selected based on what domain the user logs on to on computer?

Currently my company has been bought out by another. Due to this, another two companies users will be migrating into our office. It would be super handy if we could have the vlan chosen for the user ...
6
votes
1answer
5k views

Why would Windows Server not respond to DHCP DISCOVER?

My network was working just fine and I broke it. There is a Cisco 1711 router which was configured to hand out DHCP leases to the client PCs. I have a domain controller (Server 2008) on the same ...
6
votes
2answers
5k views

How to achieve automatic roaming between two Cisco Aironet access points?

I have two Cisco Aironet 1141 access points covering an office; the access points are configured identically (each of them with two SIDs) and are fully working; they are standalone access points, not ...
6
votes
2answers
13k views

Cisco AnyConnect SSL VPN client allows local LAN access, but not on additional multi-homed server

We have a machine for connecting via Cisco SSL VPN (\\speeder). i can ping our our speeder on 10.0.0.3: The routing table on \\speeder shows the multiple IP addresses we have assigned to it: ...
5
votes
9answers
3k views

Why DELL PowerConnect and Juniper are so rare ? Why do enterprises stick with Cisco? [closed]

I have a little question, I'm actually studing IT in France, and when looking on alternative on the very [...] very expensive Cisco equipments, I've found Juniper and DELL PowerConnect pretty ...
5
votes
5answers
1k views

Mixing SAN iSCSI Traffic with core network traffic, Am I asking for trouble?

I am configuring a new network and had a couple questions I am finding hard to find good answers about best practices on using VLANs to separate Core network traffic and iSCSI traffic. The switches ...
5
votes
5answers
3k views

Hubs/switches taking out switches?

Here's the issue...we have a network with a lot of Cisco switches. Someone plugged in a hub on the network, and then we started seeing "weird" behavior; errors in communication between clients and ...
5
votes
5answers
8k views

Is there a Cisco IOS Virtual Appliance?

Need to do test configurations on (unfamiliar) Cisco/IOS equipment. Is there a virtual machine I can light up and use it in my test environment as a real firewall/edge/core router?