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10
votes
1answer
3k views

Cisco WLC External WebAuth Apparent Random Behavior

On Cisco 5508 v7.2.103.0, I have a couple of WLANs configured. Call them ABC and XYZ for the sake of this question. ABC uses 802.1X and gets a splash page redirect URL pushed down. XYZ uses PSK and ...
24
votes
10answers
246k views

How to find the port a device is connected to, based on IP, on a Cisco Catalyst switch

On a Cisco Catalyst switch, I need to find what port an end device is connected to. I have the IP address/host name. How do I quickly find the port?
13
votes
4answers
6k views

Hardware tap vs port mirroring - Any limitations?

I predominantly work in a Cisco environment and contemplating buying a network tap device for use with Wireshark. Can anyone provide the pros and cons from their experience between using network taps ...
10
votes
2answers
2k views

Why does my Cisco 6509 BGP table use two entries in my TCAM?

I have a problem on my Cisco 6509, each entry in my BGP table occupies two entries in the TCAM. If I show capacity forwarding, I see MPLS entries in L3 forwarding resources. But, I do not use MPLS on ...
6
votes
3answers
691 views

Is there a way to test TRILL in a virtual lab?

I don't have access to devices to run TRILL for testing and learning purposes, so is there a way to set-up a virtualized lab to try it ? What would be the virtualisation system, the vendor, the ...
10
votes
4answers
1k views

Should spanning tree path costs match on a physical link?

While working on a set of switches I noticed that the spanning tree path costs aren't set up to match on opposite sides of the same physical link. For some reason that doesn't look right to me. ...
12
votes
1answer
2k views

What is the maximum prefix size routed in the IPv6 Internet?

In v4, most of the operators filter BGP updates for prefixes longer than a /24, to preserve the size of the full view. What about IPv6 ? Is there such "convention" that stands out ?
7
votes
2answers
890 views

Netflow differences between IOS 12.2 and 15.1

Has anyone upgraded their cisco routers from 12.2 to 15.1? I'm curious to know what kind of changes were made to netflow. Most specifically, I'd like to know how (if at all) the CPU utilization ...
6
votes
4answers
4k views

Are multiple links with different VLANs between two switches possible?

I'm not considering Etherchannel or LACP. Given 2 Ethernet switches A and B, where both switches have port 0 configured as a tagged trunk for VLAN 100 and 101 and port 1 configured as a tagged trunk ...
7
votes
2answers
1k views

Is it possible to emulate device other than Cisco and Juniper in GNS3 or any other environment?

For testing and research purposes, I know it is possible to emulate Cisco devices (with dynamips) and Juniper ones (via an "Olive", a FreeBSD based system running on qemu) in a GNS3 environment. Is ...
5
votes
3answers
2k views

Unable to connect via VPN to remote network

PROBLEM: I'm unable to connect via VPN to our production network while connected to my home wireless network. SETUP: Internet | ISP router at home | Cisco ASA 5505 firewall | Buffalo wireless ...
7
votes
2answers
2k views

Cisco Catalyst cluster heartbeat switch issue - increasing input errors

PROBLEM: The servers in two clusters keep losing heartbeat connectivity with each other thus causing database outages. Outages are brief but disruptive. SETUP: There are two clusters of three ...
5
votes
4answers
1k views

IP prefixes by state (geolocation) [closed]

I've been given a task of creating several filters to block outside traffic by geolocation. In the list of the places that need to be blocked there are several countries (e.g. China and India) and 5 ...
8
votes
3answers
4k views

Using Fabric on a Cisco device : “Line has invalid autocommand”

I wasn't sure where to ask this but it seems to be something on the switch side so I thought I would start here first. I am working on a little project to automate updates to config files in bulk ...
10
votes
3answers
4k views

Multiple LAN interfaces on SonicWALL

We have a SonicWALL 2400. Is there any way to assign multiple interfaces to the same LAN subnet? Basically, we would like to have X1 for the WAN and X0, X2, X3 and X4 connected to 4 devices that ...
7
votes
5answers
3k views

Cisco: monitoring users input

Is there a way to monitor a user's input on a cisco device? Clarification: the commands a user have entered as in configuration mode AND normal mode. (especialy normal mode. Configuration mode can ...
12
votes
3answers
4k views

ALU interop GRE tunnel

I've been trying to figure out how to setup a GRE tunnel between an ALU 7750SR and a 3rd party vendor. I think it's balking at the VC-ID in the SDP but i'm hoping someone has experience getting a GRE ...
15
votes
6answers
1k views

Time to switch to IPv6?

I am thinking of upgrading our networking situation and am considering a migration of IPv4 to IPv6. Is it too soon to be considering this move as it looks like much of the networking gear and OSen ...
9
votes
2answers
4k views

What is backpressure in the context of routers?

There are several references to backpressure as regards to the internal bandwidth and switching fabrics of routers and switches. What exactly does backpressure mean, and what are the real world ...
16
votes
5answers
2k views

How to choose a BGP router ID when using IPv6 only?

Usually, when using BGP, you can choose (or your device chooses four you) a router ID from one of your assigned public IP addresses. Now, let's admit you only run IPv6. As the router ID is still a 32 ...
5
votes
1answer
1k views

How many contexts can be created on a Cisco ASA Active/Standby Pair?

How many contexts can be created on a Cisco ASA Active/Standby pair with base license?
8
votes
2answers
1k views

intersymbol interference (ISI), channels, and frequencies

When describing 802.11b/g and the 2.4 GHz channels, or 802.11a/n with 5 GHz channels, textbooks (CWNA Official Study Guide) often show some figure with channels spaced such that certain channels ...
9
votes
4answers
3k views

Overcome 2 monitor session limitation in Cisco VSS

Is there a way to overcome Cisco's 2 monitor session limitation on a VSS 6500 without the use of a network tap?
55
votes
14answers
190k views

Multi-Mode and Single-Mode Fiber Differences

When cabling a network using fibre, what is the difference between single-mode and multi-mode fibre? When should I be using one or the other? Are there compatibility and/or speed concerns with either?
10
votes
6answers
11k views

Which Python modules are you using for network management and automation? [closed]

I was wondering if anyone has some favorite modules for doing things like SNMP, CLI screen scraping, netconf, etc...
10
votes
5answers
5k views

Static redistribution into EIGRP as internal failure

I am redistributing a static route into EIGRP on a 6500. I had read here if you enter a network statement matching a static route that it would be redistributed as an internal route by EIGRP. However, ...
15
votes
5answers
18k views

How to factory reset IOS-XR?

I want to factory reset IOS-XR. The router used is ASR9000 I'm used to do that easily in IOS doing config-register 0x2102, write erase followed by a reload. I search on documentation, but found no ...
6
votes
1answer
9k views

A FEX port remains inactive - how can I bring it up?

When implementing Cisco Nexus 5k switches (5596UP), I connected a server to a dual homed 2000 FEX (2232T), the port belonging to a virtual port channel. However, the port changed the status from ...
9
votes
3answers
4k views

Does varying the angle of omni directional antennas affect connection quality between WiFi APs?

I use Cisco access points AIR-CAP1552E to connect buildings via WiFi, 802.11a/n (5 GHz). Normally, they are mounted upright, with three three omni directional antennas at the bottom. Now I consider a ...
7
votes
3answers
2k views

What are the components and licensing of a full Cisco CUCME PBX?

I've been placed in charge of replacing an older Avaya TDM PBX with a new VoIP system that will integrate with Exchange (at least in the capability to transcribe voicemail messages and deliver them to ...
9
votes
4answers
4k views

Cisco-configuration syntax highlighting for TextMate/Sublime Text [closed]

I would like to have syntax highlighting while perusing my configs - does anybody know of a good Cisco IOS syntax highlighting bundle for TextMate or Sublime Text? Edited (2015-09-21) to add: GitHub ...
12
votes
3answers
2k views

Is there such thing as a network bridge?

Is there such a thing as a network bridge or is it always meant as a switch implementing a bridging function? Whilst bridges are described as devices that create separate collision domains in network ...
7
votes
1answer
2k views

Juniper SRX240H loses connectivity to upstream router

I have two SRX240's clustered together. The clustering is configured with 2 redundancy groups and then 3 RETH's. reth1 is connected to our internet connection via ge-0/0/5 and ge-5/0/5. Our internet ...
8
votes
1answer
6k views

How to force VPLS/L2VPN to use a specific path

We're using VPLS and L2VPN on Juniper MX for L2 connections. Signaling is done via BGP and label distribution via LDP. Now we want one L2VPN to use a specific path trough the network and not follow ...
13
votes
3answers
10k views

How do I read optical transmit power via SNMP on Cisco ASR9k?

I am looking to read optical transmit and recieve power of XFPs in our ASR9k. The MIB used should be "CISCO-ENTITY-SENSOR-MIB" which is 1.3.6.1.4.1.9.9.91 and occording the ASR9000 documentation, this ...
11
votes
2answers
3k views

Why don't iperf, scamper and path MTU discovery packet captures agree on the path's MTU?

Let's do some path MTU discovery between two Debian hosts separated by a Debian router that runs Shorewall-generated iptables rules. Each of the two hosts uses a single Ethernet link while the router ...
8
votes
4answers
12k views

ASA use of proxy ARP for NAT

I will be performing NAT on the outside interface of an ASA to a web server within a DMZ. I would like to disable proxy-arp on all the interfaces that I can. I know that outside interface will need to ...
8
votes
2answers
24k views

Policy routing configuration in Fortigate

I have an scenario where a Fortigate firewall is used to separate internal networks from the Internet (FortiOS Version 4.0 MR3 patch 11). Right now there is a single Internet connection attached to ...
35
votes
3answers
2k views

Why do network taps have four ports?

I've been looking at a hardware network tap like this one to replace a pseudo-permanent SPAN that's been running on a Catalyst switch. All the taps I find have four interfaces: A, B, and two output ...
8
votes
4answers
3k views

Cisco 1260 AP no longer responds to ping, ssh after upgrade to latest 15.x firmware

I have a 1260 AP that I upgraded this morning. Prior to the upgrade, the system permitted ssh and would respond to pings on the network, however now it does not respond. I hooked up a serial cable ...
11
votes
2answers
4k views

catalyst 3750x - jumbo frames on svi

I've encountered a problem on a cisco ws-c3750x-48ts-s where jumbo-frames won't cross a trunk-connection between a vwmare esx-host and the switch. The access ports in the same vlan don't experience ...
43
votes
15answers
78k views

How can I diagnose a bridging (ethernet) loop?

Given that spanning tree has failed (or you don't have any spanning tree) and get an ethernet loop, what's the best way to diagnose where the problem is? Which switch?, which cable? and so on.
9
votes
1answer
611 views

TCP Client / Server in Cisco EEM 3.0

I'm attempting to set up client / server sockets in Cisco EEM 3.0 TCL with IOS version 12.4(24)T8 (this was recently upgraded to determine whether the problem was EEM ver). I have the following two ...
11
votes
2answers
440 views

End-to-End FCoE

I have been evaluating converged storage/data networking for some time. It seems that the design pitched by vendors is a bridging of the Fiber Channel (FC) and Ethernet domains. I always come away ...
15
votes
4answers
1k views

Is Nexus 7000 series line card “OIR” impact-free?

I have read many data sheets on the Nexus 7000 series and it's cards purporting to be capable of OIR (Online Insertion and Removal). However I have never needed to replace/reseat/add any Nexus line ...
8
votes
2answers
1k views

Does Juniper set a control word on VPLS pseudowires

At the RIPE conference the was a talk about how MAC addresses starting with a 4or 6 may suffer from decreased performance because MPLS routers misinterpret the Ethernet packets as an IPv4/6 packet ...
14
votes
5answers
2k views

How to filter non-bogon prefixes received via BGP from an Internet Exchange(IXP)?

When connected to an Internet peering exchange(IXP), what is a good way to make sure that people don't send you prefixes that they shouldn't be announcing? With regards to bogons I'm aware of the ...
20
votes
10answers
5k views

Easily deploying new VLANs in a large environment

How do people handle the need to add VLANs to all switches on their network (or even a subset of devices)? We are adding around 6 new VLANs per week at the moment and as the network grows this is ...
8
votes
1answer
1k views

Migrating from STP short mode to long mode?

It was decided recently to migrate a large campus network from the short mode STP costs (16-bit) to the long mode STP costs (32-bit). I have clearly found it documented that this needs to be a "...
12
votes
5answers
4k views

What IPv6 prefixes should never be routed?

Seems clear to me that the Link Local, and Unique Local, addresses should at least be filtered. Is there anything other than LLA/ULA that should be filtered? For LLA, is it standard practice to ...

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