Questions tagged [cisco-ios]
For discussion about Cisco's Internetwork Operating System - Cisco IOS
513
questions
7
votes
1answer
747 views
How to break apart an IPv6 /56 6rd delegated prefix from ISP into multiple /64 VLANs for use with SLAAC EUI-64? [Cisco]
I have CenturyLink Internet service, and they have a 6RD IPv6 deployment where they hand out an IPv6 delegated prefix /56 block to me and allow me to use it as I wish. My Cisco ISR router receives the ...
0
votes
2answers
26 views
Show ports in use on Catalyst 3570
I picked up a used C3570 and am new to IOS. I am trying to ask the switch to show which ports are in use. My searches lead to the command "show modules" but that's refused by the switch (...
1
vote
1answer
42 views
QoS Policy to not overutilize WAN link
I have a configuration on a Cisco C897VA-K9 router that has a built in DSL modem. It has a simple internet connection via VDSL. There is a VPN configured on the device, that connects back to our main ...
4
votes
3answers
23k views
Meaning of the ip default-gateway L2 switch
What is meaning of the ip default-gateway command on a Cisco L2 switch? I read something about it on the Internet, but there was written that it allows you to Telnet to the switch. I am little bit ...
0
votes
1answer
17 views
Traffic flow of tunnel interfaces
I would like to understand traffic flow in a router. In what direction do i need to apply a policy-map in order to affect traffic? Especially regading tunnel interfaces, as traffic both comes and goes ...
1
vote
1answer
36 views
Cisco IOS NTP do not sync time after reboot
I try to setup automatic syncing time on Cisco Catalyst 2960-CG-8TC-L switch using following command.
ntp server 0.cz.pool.ntp.org
and it works and sync time but after switch reload it does not sync ...
3
votes
2answers
50 views
Understanding traffic flow on SVIs [closed]
I have a simliar question to this one: Access-Lists and VLAN and understanding traffic flow
But my question is concerning service-policies. Have a look at the image above. I triet to make a traffic ...
3
votes
2answers
1k views
Cisco IOS pick default route from two DHCP interfaces with track
I plan to have a portable IOS cisco router which will have two DHCP assigned ISP addresses from unknown ranges. A tunnel is then built through the preferred ISP to another outer.
I would like to set ...
0
votes
1answer
30 views
Cisco DHCP relay with Microsoft DHCP server
Current situation: we have a C3850 switch serving DHCP lease to desktop clients without communicating with any upstream DHCP server
Objective: We would like the C3850 switch continue to serve DHCP ...
2
votes
3answers
9k views
Show all VRFs link status summary
In Cisco IOS-XE if I want to see a specific VRF's bgp connections summary I would do:
show bgp vpnv4 unicast vrf VRF_ID summary
and the result would be as below example:
Neighbor V ...
0
votes
2answers
37 views
IOS. Whats the difference between these 2 commands
I am completing an online course for the network+ and am going through one of the labs. Here is a diagram of the network in question.
Specifically I have a switch with 24 fast ethernet ports and ...
2
votes
2answers
189 views
Restricting TFTP access from Host to Router using extended ACL in Cisco IOS
I am trying the below Extended ACLs to restrict TFTP but still I am able to upload files to the router using tftp. Not sure, what is wrong, can you all help?
Approach 1:
permit udp host <ip> ...
0
votes
1answer
54 views
Issue w/ Cisco router and failed NAT and static default route
I have a cisco router that is using a VRF to support a site to site VPN tunnel. I have added a second network to the router for non-VPN standard internet use. My problem is that my default static ...
0
votes
1answer
30 views
When do ACLs on SVIs get applied on Cisco Catalyst devices?
I don't understand exactly when an ACL will get applied when on an SVI. Given the following (pseudo) configuration
int vlan 100
ip address 10.0.0.1 255.255.255.0
ip access-list in in
ip access-...
3
votes
2answers
88 views
How can I use an HTTP CRL on Cisco IOS?
On a Cisco 867 running IOS 15.6(3)M7, I'm trying to do the following:
TEST-GW1(config)#crypto pki trustpoint vpn-p2s-server-11
TEST-GW1(ca-trustpoint)#crl query http://myvpn/crls/21.crl
% URL must ...
2
votes
3answers
9k views
Changing Label for Generic PC in Packet Tracer
I can change easily Router and Switch names in Packet Tracer using hostname command in global config mode. But how could I change a label of a Generic PC, let's say from PC0 to Sales? i could not find ...
1
vote
0answers
45 views
Upstream QoS garanteed bandwidth
In the network I'm trying to manage there is a satellite link, the upstream of which is ~ 7 Mbps. In this upstream, I need to allocate 1.5 Mbps of guaranteed bandwidth for one single host, but nothing ...
5
votes
1answer
910 views
What is the effect of using “ntp allow mode control 0”?
I am attempting to mitigate the issues surrounding bug report CSCum44673. According to the software release notes found here, I need to ensure that all of my routers are on IOS version 15.2(2) or ...
0
votes
0answers
17 views
Is it possible to specify a bandwidth parameter per service instance?
I have a physical interface with multiple service instances and policer per service instance:
interface GigabitEthernet0/3
switchport trunk allowed vlan none
switchport mode trunk
mtu 9192
...
1
vote
0answers
17 views
Configue IOS DHCP server to respond to Option 60 class
I have a number of small networks each with about half-a-dozen mostly-fixed hosts. The routers on each network provide DHCP service for the occasional visiting engineer's laptop. I am adding IP ...
0
votes
0answers
16 views
Rate limiting xFTP traffic originating from a Cisco IOS router
We have some routers on marginal cell links that we need to pull files from using TFTP or FTP. During file transfers connections to the router become so slow as to be unusable.
Is there a way to rate-...
1
vote
1answer
108 views
Lubuntu 18.04 can't SSH to Cisco Router: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1 [closed]
I'm not sure if this problem caused by Lubuntu or Cisco Router side.
Lubuntu = 192.168.1.100
Cisco Router = 192.168.1.1
Ubuntu 18.04.4 LTS
user@linux:~$ lsb_release -a
No LSB modules are available.
...
0
votes
0answers
51 views
Cisco erase nvram or erase startup-config doesn't work
According to this article, I can delete the current startup configuration files and return the router to its factory default settings with the erase nvram: and reload command.
https://www.oreilly.com/...
0
votes
1answer
47 views
Cisco IOS Sanitization: Any Way to Not Use NVRAM?
We want a method to sanitize Cisco IOS 15 routers (ISR Gen 2) before they are removed from the facility. While a "write erase" works perfectly if the router is breathing, how to sanitize dead routers ...
0
votes
1answer
47 views
implementing broadcast traffic restriction
Can we restrict the high broadcast traffic from interface in Cisco ASR9k and 7600 routers? If so, what configuration we should apply?
0
votes
1answer
36 views
Firmware of Cisco Phone
i want to configure IP phone Cisco DX650 with Sip.Anyone have idea about it how i can upload firmware of sip feature
0
votes
0answers
16 views
Cisco IE2000 - NTP Doesn't Associate
I'm having a very weird issue with a switch. It doesn't want to associate to my NTP servers.
My config is very simple:
ntp server ntp1.domain.com
ntp server ntp2.domain.com
ntp server ntp3.domain....
0
votes
0answers
13 views
What's the difference between “IP NAT Inside Source” and “IP NAT Inside Destination” commands in Cisco routers? [duplicate]
As much as i know both of this commands translate source address of packets that travel from inside to outside and destination address of packets that travel from outside to inside,so what's the ...
2
votes
1answer
30 views
Cisco snmp-server single user for multiple snmp versions
Attempting to maintain SNMP v2c compatibility while implementing SNMP v3 on cisco switch 5506cx.
Would a user that was previously used for v2c see issues with v2c if it is added to a v3 group?
For ...
2
votes
1answer
175 views
Link Aggregation from Cisco to Palo Alto using 10 gig interfaces, port on Cisco shows “waiting to be aggregated”
I am trying to bundle two 10-Gig interfaces on PA-3020 to Cisco Cat9300. Previously, I had bundled two Gigabit interfaces on same devices and everything worked fine. But now, when I try to configure ...
2
votes
1answer
52 views
Prevent static NAT to respond to ARP requests
We are trying to merge 2 networks with overlapping IP spaces: This is the configuraiton so far:
interface Tunnel1
description VPN Port CompanyA
ip vrf forwarding LAN
ip address 172.18.0.79 255.255....
2
votes
0answers
149 views
Cisco AIR-AP1852i-E-K9 stuck in “waiting for uplink[…]” after startup
I pulled an old cisco AP from a shelf today at work to test something, and after starting up and connecting with PUTTy, i was greeted with (after startup), this - repeating over and over:
[*02/16/...
0
votes
0answers
29 views
Cisco PPTP server available routes protocol
I have a 2921 Cisco router in one place, and a Windows XP computer on another.
I made my Cisco router as PPTP server, and my XP computer as a client.
The router is located within a LAN with address ...
0
votes
0answers
40 views
Cisco C3750 and PRTG netfllow
I have a core switch (backbone) of our network that broadcasts all the vlans to other switches. I am trying to configure netflow on the switch and link it up to a Netflow sensor on PRTG.
I followed ...
4
votes
1answer
2k views
Disable reset button on Cisco 2950?
On the front panel of a Cisco 2950 is a button which can be used to reset the switch to factory defaults, when held down for a few seconds.
Does anyone know of a way to disable this within IOS?
Many ...
1
vote
1answer
94 views
What is the difference between trustpool and trustpoint on Cisco IOS?
On Cisco IOS, there is trustpool and there is trustpoint. I have seen imported certificates in either of the two. And it seems SSL connection works when either location has the certificate it needs. ...
2
votes
2answers
423 views
Listen-only (stealth) CDP on IOS
I would like to put my router in a listen-only mode for CDP i.e. it should allow CDP packets to only arrive while not advertising so that I can glimpse into physical topology while remaining hidden to ...
2
votes
1answer
548 views
Why would you use port security mode “protect?”
Port security offers three violation mode options:
• protect—Drops packets with unknown source addresses until you remove a sufficient number of secure MAC addresses to drop below the maximum value....
1
vote
2answers
61 views
Cisco Switch without VLAN support?
I've been reading about VLAN and wondering is there any Cisco Switches that do not support VLAN?
So far, all switches that I found do support VLAN. This is one of the example in my lab.
Cisco-Switch-...
0
votes
0answers
40 views
Cisco Guestshell - Bridging of VirtualPortGroup0
i'm fiddling around with ne virtual-services functions of IOS-XE.
Is there a possibility to bring interface "VirtualPortGroup0" into a bridge domain with some physical interface of the router?
It's ...
0
votes
2answers
44 views
Why doesn't kernel itself had entire L2/L3 protocol stack? [closed]
I know kernel itself handles protocols in layer 2, layer3 and layer 4 at ipv4 stack, but why can't kernel itself doesn't have protocols such as STP/RSTP/xSTP/OSPF...etc, implemented.
Why should we ...
3
votes
2answers
150 views
Decreasing SNMP update timer on IOS-XR (CISCO ASR)
I've a case where i'm trying to poll SNMP information every 10 seconds from a Cisco IOS-XR devices (interfaces mib). Seems like CISCO IOS-XR updates SNMP information every 15secs, so sometimes ...
1
vote
1answer
89 views
TCP handshake immediately RST [closed]
I'm trying to set up a modbus TCP connection on port 502 but get a RST packet immediatly. So the TCP connection handshake doesn't even succeed.
This is done on a windows machine on an ESX server.
The ...
1
vote
1answer
51 views
Filter tagged route to downstream routers
I'd like to filter a redistributed route from EIGRP into OSPF to all routers in AREA2 and AREA34. I have tagged the route 10.90.100.0/24 with tag 90 at the Tampa router where its redistributed into ...
0
votes
1answer
56 views
Cisco Zone Based Firewall
I have Cisco 891F configured with ZBF from CBAC. Right now, router is wide-open SSH/443 or anything my public address is listening on, which is not what I intended. My intention was to only allow IMCP ...
0
votes
1answer
33 views
WebAuth With RADIUS For Switch Web Portal
I have a Cisco IE4000 running IOS 15.2. I am trying to login with my RADIUS credentials to the web portal for the switch. Currently the RADIUS is configured for successful login to Console and SSL but ...
0
votes
1answer
43 views
DHCP when you have both layer 3 and switch ports
I have the following config:
ip dhcp pool Vlan10
network 192.168.1.0 255.255.255.0
default-router 192.168.1.1
interface GigabitEthernet0/0
!
interface GigabitEthernet0/0.10
encapsulation ...
1
vote
0answers
68 views
HTTPS QOS and policing [closed]
In our office, everything runs on HTTPS. We have softphones and web-based clients which are high priority. We also have Google search, maps and other low priority websites that should work on best-...
0
votes
0answers
55 views
cisco zone-based policy firewall
How to limit the number of established connections for each host, that connect to the service? In the policy settings, I found only blocking by the number of half open connections.
parameter-map type ...
0
votes
2answers
116 views
What does the Cisco HTTP client (help to) do on a switch?
While checking for vulnerabilities in one of our Cisco switches I came upon this: CVE-2019-12665.
Excerpt from the CVE:
A vulnerability in the HTTP client feature of Cisco IOS and IOS XE Software ...
