Questions tagged [cisco-ios]

For discussion about Cisco's Internetwork Operating System - Cisco IOS

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Is it possible to set maximum 32 PAT translations per global ip address?

So basically I'm trying to configure a cisco router (c7200) to use PAT with a pool of global addresses, and each global address should only support a maximum of 32 private addresses. I've been ...
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GNS3 Router Telnet Configuration

I configured the IP address and telnet for my Cisco router but on GNS3 it shows a different IP address. When I ping the router from my Ubuntu virtual machine using the IP address I configured the ping ...
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Show on a Cisco 3850 Switch if a new IOS is installed

We have some Cisco 3850 that we never get downtime to do software upgrades (current uptime of switches is over 4 years). Tomorrow there is power works in the room so these switches will lose power so ...
1 vote
2 answers
67 views

What interfaces does a Cisco iOS Router allow SSH Console access on?

I am have trouble understanding how Cisco iOS maps console access services like SSH to IP addresses. Assume the following: There are no acls blocking traffic There is the typical SSH server ...
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1 answer
63 views

Naming ASN something else than "default", Cisco IOS XR

I'm trying to configure a BGP and VRF (for a L3VPN) on a Cisco ASR9000 router, as per this tutorial. I'm on the first section ("Configuring Multiprotocol BGP on the PE Routers and Route ...
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1 answer
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How to change the AS number without losing the old BGP configuration?

I use Cisco with IOSv and would like to change AS number without losing the old BGP configuration.How to change the AS number without losing the old BGP configuration?
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What could be blocking ARP?

I have a metro ethernet link between two offices with Cisco C3560X's on each end. Actually, I have two links. (We are switching from one provider to another.) I can't get the new link to work. Pinging ...
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Admin IOU L3 switch

Problem with IOU l2 switch By Konstantinos Dimos July 31, 2022 at 3:12 UTC Hi, under Ubuntu 22.04 LTS, gns3 and local server I am trying to manage switch IOU L3 switch, although at the begining I was ...
1 vote
1 answer
149 views

how to limit or block broadcast traffic on ASR920 service instance EVC

I don't want to turn off all port, I want to block completly broadcast traffic, or the best to limit rate to 500 pps broadcast, all more to drop. Is there any way to do it on Cisco ASR920? I have ...
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Cisco Access Switches: Monitoring AAA server dead via SNMP?

This is a new setup of Cisco access switches (2960S, 2960X IOS with 15.2(2)E9, but mostly C1000 with IOS 15.2(7)E*), with a Cisco ISE 3.0 as authentication server for 802.1X, config style is to be ...
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BGP Protocol configuration between two VPC

I would need to configure a cross connect between two VPC networks via SFP Fiber. Unfortunately I'm new on BGP configuration and would need confirmation that I'm doing it on the right way... I have ...
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Cisco ASR 1001 transceivers not working

I've a Cisco ASR 1001 v03. When it got to my hands it wouldn't save the config after reboots, after some research I found out the config-register had a wrong value and it was fixed by running ...
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Cisco 9400-Supervisor Engine 1XL uplink help

I have inherited a Cisco 9400 with 6 line cards installed. I am trying to use some ports on one of the cards. I noticed that there is no link activity lights, no indication of any activity. I think ...
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Cisco 4500X TCAM question on PBR

I have a pair of 4500x in VSS mode and i have 100-150x SVIs and i have PBR under those SVIs and i am changing their next-hop, i want to know PBR and changing next-hop happens in TCAM, hardware or it ...
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No Adjacency-SID label in packets in SR topology

I configured Segment-Routing on Cisco IOS XE 17.03.3 in lab environment. You can see topology in the attachment. I configured IS-IS as IGP protocol. It also advertise SR labels. Global-SID static ...
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Cisco ACL Entries

I have a cisco 4500x and n5k-5672up and in their datasheet mentioned that we can have "Security ACL Entries (1K=1024) 128K (64K ingress and 64K in egress) Shared with QoS" for 4500x and &...
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TACACS Through ASA L2L Tunnel

Hello see below network diagram. I am trying to configure the Branch Router (10.1.1.1) to use TACACS AAA on the HQ-AAA-Server host (192.168.10.10). TACACS works fine for the Branch-FW1 ASA device ...
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Problem with BGP aggregate-address behavior in IOS when a large number of OSPF routes update all at once

We have a Direct Connect setup to AWS using BGP. We are running a ISR4451 with IOS XE 16.03.06. I have a strange situation where the AWS BGP neighbor drops our connection with the notification: ...
2 votes
1 answer
124 views

AAA Authorization on IOS

Still working away on a project (not for real life deployment so don't worry about seeing passwords). I have a Tacacs server set up for centralised AAA. I am trying to set up two users, "admin&...
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events log in cisco

Is there log file just like events file in windows showing what happened,who did what, kind of ? I could not see with show archive log.some switch goes down and support guys plug off/on cisco switch, ...
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Route-map to manipulate metric in EIGRP

I have following Setup R1 --- R2 --- R3 --- R4 --- R5 The same network is being advertised from R1 and R5. There is some difference in delay between the two paths R1-R2 and R4-R5. So the route from R1 ...
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4 votes
3 answers
245 views

IOS Memory allocation error after ping

I have written a script in Tera Term for a Cisco IR809g which pings 3 different routers(IR 809g) in 2 different networks over the cellular interface. After +- 6 hours I'm getting a Memory allocation ...
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Update IOS on Cisco CGS2520 Switch

I need to update the IOS on a Cisco CGS2520 Switch. Not stacked, single switch I have never done this before and I have a couple questions. I do not have physical access to the switch. Looking at the ...
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How do I load VLAN database between switches (CISCO 2960)?

I glad for any help on this topic -- netanel
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2 answers
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Client's ARP requests affect whether Cisco C897VA receives packages or not

So I have bought used ISR C897VA with an issue: when vlan1 is pinged from windows there are quite a lot of "Request timed out"s. Config-register 0x2142 has been done, as well as resetting ...
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No Voice commands on cisco router

I cannot find voice commands on my router, I have licenced it but no voice commands or sip are found Its on packet tracer. Cisco router 2911 Thank you
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Addresses in router's subinterfaces overlapping [duplicate]

I can't really understand why I'm getting overlapping addresses in subnets when they're between the allowed range. I have the network 192.168.1.0/24, and I have to create 3 subnets: A - 58 Hosts B - ...
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How to query which line I am configuring in a Cisco router?

The Cisco router prompt shows only that I am configuring a line: config-line. How can I make IOS to print exactly which line I am configuring?
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1 vote
1 answer
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ARP sending an ARP request on changing port IP address

Using the c7200 images on GNS3. I configured two routers as so: With arp debugging on, after assigning an ip address I see that each router sends a gratuitous ARP response packet (only debug output ...
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Cisco DHCP using dynamic updates

I would like to use a configuration on a Cisco router that allows for clients to resolve the names of other clients without the use of mDNS. I have following configuration: roTST01#show running-config ...
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344 views

Can ping from VPC 1 to router and VPC2, but can't ping from switch to VPC2 or router

I have a simple, linear topology in GNS3 that goes like this. VPC1 > Switch > Router > VPC2 I have the default static IP Routes on the router set to 0.0.0.0 0.0.0.0 Ethernet0/1 and Ethernet1/...
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How to stop automatic entry as privileged exec from console login?

I am configuring my Cisco router and trying to set up access levels. I was under the impression that level 0 was a very limited mode which almost only allows users to enter the enable command to enter ...
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2 votes
2 answers
164 views

Unable to add an abbreviated IPv6 to a Cisco router

I am very new to networking and playing around with GNS3. I am trying to configure a router to have 2 IPv6 addresses in a single interface (as far as I understood, this is possible with IPv6) I ...
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1 answer
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IP Source Guard On Static Networks

I am running a set of Cisco C9300s. I have them configured with ip dhcp snooping, and ip arp inspection with ip dhcp snooping trust and ip arp inspection trust set on the fiber link between the 2 ...
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In France , what language is the Cisco IOS for routers and switches?

If I accept a Network Engineer job in France, what language will the Cisco , Juniper, etc, IOS communicate in? If it is in French, is there an acceptable workaround that I can install in routers that ...
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Why does a Cisco router advertise a prefix with NDP RA when it has an address in that range?

If I write interface Vlan1 ... {ipv4 config} ... ipv6 address 2001:DB8:5432:101::/64 eui-64 ipv6 address FDAA:DB8:5432:101::/64 eui-64 ipv6 enable ipv6 nd prefix 2001:DB8:5432:101::/64 ipv6 nd ...
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204 views

Steps for upgrading to Cisco DNA Center?

Has Anyone upgraded from cisco Prime to Cisco DNAC, if so then Does anyone have Steps (Prep Work) checklist suggestions before beginning the Brownfield Deployment of Cisco DNAC ?
3 votes
1 answer
252 views

Cisco ACL numbering

This is a small technical question. I can't seem to find any information on this, so I thought I'd ask here. I'm currently studying for my CCNA and I'm currently on the topic of ACLs. On IOS standard ...
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1 answer
519 views

4500x ios upgrade

I have a Cisco 4500x-32SFP (with Enterprise License) with cat4500e-universalk9.SPA.03.04.04.SG.151-2.SG4.bin ios and i want to upgrade it to cat4500e-universal.SPA.03.11.03a.E.152-7.E3a.bin which is ...
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270 views

Cisco ip helper-address

I am looking at the DHCP documentation and i cannot seam to find how to configure the router to use a loopback interface as the relay-agent. My objective is to use option 82 so that the dhcp server is ...
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1 answer
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Multiple administrator connecting to a router - who has precedence? Can they monitor each other's logs?

Just getting started in Networking. Came across multiple administrators connecting over Telnet. Does someone who connected first have precedence over everyone else? Does a admin connected to VTY line ...
5 votes
3 answers
8k views

How to remove switchport mode access from Cisco Switch 2960?

This is in Cisco Packet Tracer - this is not a real switch. Default interface config on Cisco Switch 2960 looks like this ! interface FastEthernet0/10 ! Then I put it in switchport mode access ! ...
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1 vote
1 answer
600 views

IP SLA VS tracking IP-route reachability for HSRP

I have two Cisco switches A and B, which I want to use HSRP to track if route to specific IP still works, but according to my understand it could be either IP SLA or tracking IP-Route Reachability ...
0 votes
1 answer
241 views

IPCP removing default route when 2 available

I've been stuck on this one in my lab for a while. Any help is appreciated. Here's my CPE edge topology: https://i.imgur.com/UZ4u0XG.png Take the below scenario: I have 2 circuits coming in that I am ...
2 votes
2 answers
2k views

Why does the CISCO's command 'enable secret <password>' produce different hash from MD5?

I am configuring a CISCO's 4331 router password, in Packet Tracer. More specifically I use the command enable secret weakpassword. This command uses by default MD5 to hash the last string (i.e ...
1 vote
2 answers
1k views

Safe to remove ip default-gateway?

We recently changed IP schemes from 192.168.x.x to 10.x.x.x In doing so, I noticed that the prior network engineer had ip default-gateway in the configuration pointing to an old default gateway that ...
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2 votes
1 answer
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Cisco router with 3 spaces between `deny` and `icmp`

I was configuring deny icmp any any traffic when I realized it was not in the config. I verified it with do sh run | i deny icmp command as follows: R1#configure terminal Enter configuration commands,...
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Cisco IOS How to dynamically change the queueing/shaping upload bandwidth for xDSL circuits?

In Cisco 29xx routers with IOS 15.7, we have upload queues (with the classic service-policy output command and the policy-map: policy-map wan-shaping class class-default shape average 1024000 ...
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2 answers
119 views

Add allowed vlan to vlan.dat automatically

I have a switch configuration for a Cisco 2960cx that allows a specific VLAN on a trunk but no interface on the switch explicitly accesses that VLAN. So when the configuration is ran for the first ...
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Dual WAN with each ISP in a VRF - Cisco IOS

I have a DMVPN spoke router setup almost identically to the spoke configuration listed here (Also quoted below): https://www.cisco.com/c/en/us/support/docs/security-vpn/dynamic-multi-point-vpn-dmvpn/...
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