Questions tagged [cisco-commands]
Used for questions about the commands for Cisco devices.
215
questions
48
votes
24
answers
103k
views
How can I see which switchports are not in use?
On a large Cisco Catalyst switch stack, almost all switchports are patched. I need to identify the ports, which are not in use, for connecting further devices.
Following switchports, cabling, patch ...
25
votes
5
answers
29k
views
Accidentally Removed Allowed VLANs from Cisco Switch Dot1Q Trunk
I am adding a new VLAN to an existing trunk port between two Cisco Catalyst switches (3750's). In the process of adding the new VLAN, it appears that I've removed the existing allowed VLANs on the ...
18
votes
2
answers
37k
views
Cisco - display ALL routes using a single command
In Junos when you use a show route it displays the routing tables , starting with inet.0 ( global routing table) and then listing each VRF in alphabetic order.
I am after a similar command , for the ...
16
votes
5
answers
239k
views
How can I reset a VPN tunnel on a Cisco ASA?
On a site-to-site VPN using a ASA 5520 and 5540, respectively, I noticed that from time to time traffic doesn't pass any more, sometimes just there's even missing traffic just for one specific traffic ...
16
votes
3
answers
71k
views
What does logging synchronous command do?
Can somebody describe me what does
logging synchronous
command do ?
14
votes
1
answer
2k
views
BGP "no synchronization" command not showing up in running-config
I noticed in the running config I don't see the no synchronization command under the BGP section. Is this a default command so I won't see it unless I change it?
Hardware / software
Cisco 1921
c1900-...
11
votes
11
answers
4k
views
Locate a host on Network
What is the best method of locating a particular workstation on a VLAN ?
I sometimes need to do this, if a workstation IP address, shows up on an ACL Deny
torrent use
High bandwidth usage (Top ...
10
votes
5
answers
3k
views
How can I speed up CLI typing in Cisco IOS using shortcuts?
I know we can use auto-completion (tab key) and abbreviated commands (such as sh ip int bri) to speed up typing.
However, I'm still not satisfied with typing crypting chains such as sh ip dh sn bi | ...
10
votes
3
answers
15k
views
Cisco: prevent vlan's of communicating with eachother on cisco router (ACL alternative)
Setup: Cisco router with multiple VLAN's configured on it.
How can you prevent 2 VLAN's communicating with eachother? Normally I would do this with ACL's like this:
access-list 102 deny ip 1.1.1.0 0....
10
votes
1
answer
380
views
Deconfigure an interface in IOS with one command
I was wondering if there is a single command to clear a single network port's configuration? (wipe switchport, portsecurity,...)
10
votes
2
answers
4k
views
How can I disable SIP on IOS 12.x
How would I disable SIP on an Cisco router running IOS 12.x?
10
votes
1
answer
5k
views
Cisco IOS: Show ip route output order
I am runing some BGP tests through the lab before rolling them out in production (thus, any IP addresses or AS numbers etc used here are done so in a completely fictitious manner).
Something that has ...
10
votes
2
answers
3k
views
What do these three options in a Cisco Router NAT configuration mean?
In a standard Static PAT configuration, where one IP:Port combination is always mapped to another IP:Port combination, there are three possible combinations of inside/outside/source/destination that ...
10
votes
1
answer
2k
views
QoS between two VLANs with Cisco 881 Router (IOS)
I'm hoping to get some advice regarding the best practice to delegate a limited Internet connection between two VLANs. In my case, one VLAN is for an office network, and the other is for guests. What ...
10
votes
1
answer
20k
views
Cisco config example for Policy Based Routing
I find my self in a situation I was in not too long ago, but I can't
remember how I resolved it :)
The Scenario
I have a Cisco IOS router with a LAN interface (fa0/0) and a WAN
interface (fa0/1), ...
10
votes
1
answer
5k
views
PPPoA ADSL Configuration with external modem on Cisco 891
Context
We use Cisco 891 routers as CPE for several client sites. They are all running IOS 15.
Cisco IOS Software, C890 Software (C890-UNIVERSALK9-M), Version 15.0(1)M8, RELEASE SOFTWARE (fc1)
The ...
9
votes
5
answers
10k
views
Monitor specific traffic type on a Cisco router
Is it possible to monitor a specific traffic type going through a cisco router? (like monitoring via wireshark)
Ex: I want to monitor http traffic specifically that is passing through a router. (or ...
9
votes
1
answer
57k
views
Diffrence between "wr" and "copy running config to startup config"
For saving configuration in Cisco devices we have "wr" and "copy running config to startup config" i am curious what is difference between these two command.
9
votes
3
answers
714
views
Why does "show adjacency" take so long to run?
Why does the "show adjacency" command take so long to run (in the order of minutes) on Cisco IOS Software, 7200 Software (C7200P-SPSERVICESK9-M), Version 12.4(4)XD5, RELEASE SOFTWARE (fc1)? The ...
8
votes
1
answer
7k
views
About the inside local and outside local and inside global and outside global
I have some concept problem with the NAT. Here is the Cisco definition for the local and Global and the NAT operation.
Local address—A local address is any address that appears on the inside ...
7
votes
5
answers
4k
views
Why does the Cisco show run command not show the full version, while the show version command does?
Is there any reason why Cisco show run does not show the full version which is 16.3.7 in this example?
IOSSW#show running-config | include ersion
version 16.3
while show version does?
IOSSW#show ...
7
votes
2
answers
3k
views
What is the difference between "ip domain name" and "ip domain-name"?
I'm running a ISR 4221 with "Cisco IOS XE Software, Version 16.04.02".
I see that it has both ip domain name and ip domain-name commands. Why? Is this some sort of compatibility thing? My 7206 ...
7
votes
2
answers
3k
views
Configuring redundancy using floating static
I wanted to post my network layout, but I dont have the required reputation. So I have made up a network diagram below:
ISP
/ \
/ \
/ \
HQ------Branch
| ...
7
votes
2
answers
5k
views
"transport input" for AUX port in Cisco routers
On physical layer AUX port works on asynchronous serial RS-232 protocol. However, one can specify various application layer protocols like telnet or SSH as allowed input protocols under AUX line ...
7
votes
2
answers
3k
views
"Local Policy Denied Prefixes" in 'show ip bgp neighbor' output
I've been spending the last week or so troubleshooting some (maybe related, but probably not) issues with Quagga. I have a test router - 7204VXR-NPEG2 running 12.4(24)T6 - with a single BGP session to ...
6
votes
2
answers
40k
views
What does no shutdown command do? Cisco
Newbie here. I'm studying networking and struggling to understand the no shutdown command. I don't understand what no shutdown command actually does. I've read that it enables the interface but I don'...
6
votes
2
answers
4k
views
SNMP and Syslog in configuration
Really stupid questions guys so I apologize. When sending Syslog messages to a server we use the command logging x.x.x.x. I get that part.
SNMP is used to gather stats or change configurations on ...
6
votes
2
answers
6k
views
Cisco show log number of messages
When I run the "show log" command, it displays the latest 360 messages.
Why 360?
Can this value by changed?
If yes, what is the command for that?
Thanks.
6
votes
4
answers
24k
views
Reconfiguring Layer3 Switch to enable IP routing and become the default gateway
Current configuration with HP Procurve 2848 switch at a colocation facility consists of using the ISP switchport as the default gateway. The current configuration is very basic with only 1 vlan assign ...
6
votes
2
answers
17k
views
VLAN Interface is down, protocol is down
I have Cisco Layer 3 switch with IP routing enabled on it. I have different VLANs configured on it and its working perfectly. Now i have added another VLAN (SVI) and assigned that VLAN to one of the ...
6
votes
2
answers
2k
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 <------...
6
votes
2
answers
61k
views
Show connected (up) interfaces on cisco devices
Is there any way to show a total count of interfaces that are in status "up" on a cisco router?
The purpose is to let a script go through all routers and show a summarization count of "up" interfaces....
6
votes
1
answer
3k
views
How do I create an SSL CSR via CLI for Cisco Prime?
I'm trying to create a csr for a cisco prime server.
I managed to create a csr and put it in the "defaultRepo", which is local on the disk. After what I've read I need to create a certificate repo ...
6
votes
1
answer
6k
views
Chassis temperature and Fan status on Cisco 3548 switch
I need to remotely check the status of the fans and temperature of a switch that I currently do not have physical access to. I have done so in the past on a 2950 with the command:
Show environment
...
6
votes
1
answer
3k
views
Cisco 867 forward UDP port range
I need to forward an UDP port range to a specific private IP address in my LAN.
In order to forward one port to an internal IP I do:
access-list <acc_list_number> permit <port_type> any ...
6
votes
2
answers
4k
views
SNMPv3 Setup - Cisco 3750
I am not a network guru by any means but need to setup our router/switch to use SNMPv3. I am installing What's Up Gold on our system and configured the settings (changed for this post) as follows:
...
5
votes
3
answers
58k
views
How IP helper address works?
How IP helper address works and what is the difference between dhcp and IP helper-address .please explain in brief.
5
votes
1
answer
5k
views
How to Disable telnet on Cisco switch totaly?
I have disabled telnet on Cisco 2960G switch by putting:
line vty 04
transport input ssh
but now when I try telnet to the switch I get message saying,password required but not set
I am wondering ...
5
votes
2
answers
1k
views
spanning tree RootGuard question on vPC switches
I have following diagram and two distribution switch connected back to back over vPC
Related spanning-tree question is it ok to use RootGuard on both distribution switch where access switch is ...
5
votes
2
answers
6k
views
Cisco: No autostate on GigabitEthernet interfaces, any alternative? (not working)
I recently tried the command "no autostate" on a GigabitEthernet interface (on a newer router) and this didn't work anymore, does anyone know why this is occuring? This use to work on FastEthernet ...
5
votes
1
answer
13k
views
time based interface shutdown on cisco router
Is there a way to shutdown an interface on a Cisco router based on time periods?
I would like to shut the cellular interface when it is not necessary.
Can this be done with the event manager and ...
5
votes
4
answers
41k
views
Cisco Router Telnet Connection Refused
I have a cisco 1941 router just configured but no matter how I go about configuring the telnet, it seems not to work.
It has interfaces already set up and systems can browse through it in the office....
5
votes
1
answer
500
views
"Protected" switchports on a Cisco 881W
I want to configure a Cisco 881W to deliver Corporate wired and wireless connectivity, plus Guest wireless connectivity on a second SSID, connected to the core by a site-site VPN. I was expecting to ...
5
votes
2
answers
2k
views
Order of entries in "show ip bgp x.x.x.x"
Router# show ip bgp 10.3.3.3 255.255.255.255
BGP routing table entry for 10.3.3.3/32, version 35
Paths: (3 available, best #2, table default)
Multipath: eBGP
Flag: 0x860
Advertised to update-groups:
...
5
votes
3
answers
4k
views
Cisco Switch (Cayalyst 2960-X): How to add a rule to the access list that filters out l2tp packet when a specific MAC address appears in it?
I am using a Cayalyst 2960-X series Cisco Switch, Whose 2 SFPs are connecting between 2 hosts (A,B).
A,B are connected to the switch's 1,2 ports respectively.
The host communicates using an l2tp ...
5
votes
1
answer
672
views
Enable traps on FIB (Forwarding Table) changes
I've been working for weeks to enable sending traps for FIB changes on our Cisco 2600 router. I finally found this command is responsible for that:
snmp-server enable traps cef peer-fib-state-change
...
5
votes
1
answer
531
views
Traffic marking is not working properly in QoS
Traffic marking is not working properly in QoS.
I have a problem with the policy map marking bit. I would like to monitor the traffic that matches the IP precedence bit 4 in Po 50, but from the ...
5
votes
1
answer
296
views
Need Zyxel Speedlink router to communicate with Cisco 886VA router
I'm trying to connect a Zyxel Speedlink router to a Cisco 886VA.
The problem is that the FE ports on the Cisco 886VA are switchports and I can't assign the ports an IP address directly. Therefore, I ...
5
votes
1
answer
696
views
Time Cisco Router reload not always mentioned
Im trying to measure our cisco router availability data based on downtime happened. I assume from show version, the time mentioned in tag "System returned to ROM" is when reload started, and next line ...
4
votes
2
answers
600
views
Passive interface default - issue
I was trying to configure ospf router, I have a router connected to FW in G1/0/10 and mpls router connected g1/0/1, when i typed passive interface default in the ospf router i lost all connectivity ...