Questions tagged [cisco]
The major provider of networking equipment. This is a generic tag to be used when no more specific tags are available. See the list of tags in Help Center Tag page.
3,764
questions
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SPAN/RSPAN monitoring VLAN vs Interface
I am a little lost with regards to the concept of capturing every traffic passing a core switch. If we set our monitor source to be all VLANs in a L3 switch, does that mean that traffic coming from a ...
- 3
0
votes
2
answers
61
views
Add ip-helper to vlan did not have an ip address
I have a question
i have vlan921 did not have ip address in the Core switch, I'm able to add the IP-helper to it and will not causing me any issue?
interface Vlan121
description data
no ip address
...
- 41
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0
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123
views
Why `commit replace` left traces of login accounts on Cisco IOS-XR?
Wiped the startup-config with commit replace on our ASR 9006 routers in the global config. Noticed that after a console timeout that it prompts for an account to login. Logging in with an old account ...
- 1
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votes
0
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9
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Identify first six /49 blocks out of ABCD::/32 [duplicate]
The answer is given as
ABCD:0000:0000:0000:0000::/49
ABCD:0000:0000:0000:8000::/49
ABCD:0000:0000:0001:0000::/49
ABCD:0000:0000:0001:8000::/49
ABCD:0000:0000:0002:0000::/49
ABCD:0000:0000:0002:8000::/...
- 61
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votes
1
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137
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Cisco Meraki versus Cloud-Based WLC Deployment
A networking course that I follow mentions that we can centrally manage our APs in the cloud and that Cisco Meraki is a popular solution for that.
But then again, we can also have a Cloud-Based WLC ...
- 783
1
vote
1
answer
35
views
Is there an IGMPv1 querier router after all?
I recently looked into the mechanics of IGMPv1 and v2. Reading RFC 1112, I understand that in IGMPv1, the Querier Router functionality does not exist. All IGMP configured routers in a local network ...
- 183
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votes
0
answers
28
views
Cisco Firewall 5512 NAT cause IP randomly mapping to the host
I have an ASA 5512 firewall that has configured with 2 public IP addresses.
I use static nat to explosive https service and use PAT to allow my DMZ web server to access the Internet. The CLI are shown ...
- 1
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2
answers
180
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Cisco 9200L has empty config after IOS update
I have uploaded the newest recommended image on a C9200L switch, and its running the new version now. But the config is empty. Do i need to copy the old config again or how do i recover the old config ...
- 79
3
votes
2
answers
256
views
NETCONF namespaces
I am trying to extract information via NETCONF from an IOS-XE device.
I am using two separate methods to achieve this and cannot replicate the success of one method while using the other:
Successful ...
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0
answers
91
views
Limit switch interface symmetric bandwidth on a Cisco SG300 switch
I got the job to limit the speed on a cisco 1GBit interface so that the link will have 100MBit symmetric and a burst limit of 1GBit. Its the internet uplink for a customer vlan. I am a bit confused ...
- 79
1
vote
1
answer
188
views
Unknown command rename on Cisco Router
I try to rename a file on a Cisco 2911 router by issuing
rename flash:/asa842-k8.bin flash:/old.bin
but get the error message
Router#rename flash:asa842-k8.bin flash:old.bin
^
% Invalid ...
- 79
1
vote
1
answer
68
views
We want to see where the traffic is going on a Cisco 1140 firewall.. is there a way to do this? Need more than hitcounts [closed]
looking to see if there is a way to find out where traffic is going and coming from on a Cisco 1140 running FTD .... We need more than just a hit count...
- 11
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votes
1
answer
50
views
Cisco Firepower 4110 CLI regular expression help
We have an automation, that logs into our firewalls and lists all NAT pools and the allocated connections using the show nat pool command. We want to limit the output, if possible to only show 2 or ...
- 1,732
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votes
1
answer
625
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Cisco NGFW FTD NAT/PAT pool exhaustion monitoring
We have a customer, who rarely experiences NAT/PAT pool exhaustion on their Cisco Firepower NGFW 4110. While syslog will helpfully notify us that there's an immediate problem, we would really like to ...
- 1,732
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votes
3
answers
126
views
DNS Servers and Host Names
I was studying how to set up DNS on a Cisco router, and I got confused on this piece that stated:
"Next step is to configure your DNS server with the host names of your local network, this way ...
- 11
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1
answer
168
views
Packet tracer is changing my addresses ipv4
Could someone help me with this?
I have a subnet with the ip: 172.16.193.0 in the fastethernet 0/0 of my router and when I go to put it in RIP the Packet tracer is changing it for another ip:172.16.0....
- 9
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2
answers
47
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What command would let me know Which connection links are participating VLAN 2 spanning tree?
Which connection links are participating VLAN 2 spanning tree?
- 11
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1
answer
29
views
Cisco business cbs110-8t-d lag spike [closed]
I bought this switch to have peace, no luck. I have 1 gbps fiber going into my main router. then I have an rj45 cat 6 wire that goes to my cisco 8 port switch. Then each port is used by an rj45 wire ...
- 103
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0
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156
views
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 ...
- 383
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votes
1
answer
2k
views
VTP VLAN configuration not allowed when device is not the primary server for vlan database
I have a VTP server and 4 VTP clients. I wanted to create new VLANs on the VTP server and get the error
VTP VLAN configuration not allowed when device is not the primary server for vlan database.
The ...
- 79
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votes
2
answers
231
views
Cannot get inter-VLAN routing to work
The router at the top is from the ISP and I have no control over things like WAN, NAT, etc.
Network 192.168.1.1/24 is fine, but I cannot get inter-VLAN routing between VLANs 1 and 55.
PC 1 cannot even ...
0
votes
2
answers
63
views
Static routing Cisco packet tracert
Im new with Packet Tracer，
Regarding the problem of static routing, I have a question and want to ask,
I simulated static routing of three L3 switches on packet tracert,
Now, PC1 and PC2 can be ...
1
vote
0
answers
660
views
Nexus 7706 - switchport trunk allowed vlan not working - all VLANs are being allowed
I noticed that my two Nexus 7706 do not limit the trunk VLANs to what switchport trunk allowed vlan is set to.
Sample configuration:
interface Ethernet1/15
switchport
switchport mode trunk
...
- 226
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votes
1
answer
550
views
Why my PCs can't get dynamic IPs from DHCP Server?
In Cisco Packet Tracer I created following network
Following is how I configured the DHCP Server
But the computers can't get IP addresses - getting "DHCP failed" message. Why? Please ...
- 103
1
vote
0
answers
99
views
Cisco 3850 not saving port config [closed]
I have a 3850 and whenever it reboots it loses its config. Power went out for a second today and it lost its port config. Weird thing is - it keeps the vlans. I have gone through this three times. I ...
- 111
1
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1
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1k
views
Can Traffic pass a trunk if its not allowed but set as native vlan?
If i have configured 3 vlans
vlan10
vlan20
vlan30
and then i make 2 trunkports
int gi0/1
description trunk1
switchport mode trunk
switchport trunk allowed vlan 20
switchport trunk native vlan 10
...
- 79
0
votes
1
answer
576
views
Not shows Mac address in the Core Switch
Hi everyone i have a question, i have a device connected to the port in the Core switch, It's for LAN connected to Secomia device and the LAN port is configured and we checked in the firewall we see ...
- 41
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2
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233
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 ...
- 135
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1
answer
275
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 ...
- 1
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1
answer
192
views
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?
2
votes
2
answers
560
views
Why do 802.1Q trunk ports drop tagged frames with the same ID as the native VLAN?
I'm taking a course on the CCNA and when learning about VLAN tagging, I came across this:
"If an 802.1Q trunk port receives a tagged frame with the VLAN ID that is the same as the native VLAN, it ...
- 23
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114
views
How to NAT a unicast address to a broadcast address?
I have a 800-Series router connected in the following configuration:
Port GigabitEthernet7 is connected to an external server (192.0.2.251) that sends unicast UDP to destinations 192.0.2.42:45100 and ...
- 1
3
votes
2
answers
3k
views
Show port on Cisco switch that mac address is being dropped on
We use ISE to handle port security on our switches. When I see that there is a mac address being dropped by the switch it doesn't show what interface this mac is patched into.
#show mac address-table (...
- 383
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2
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278
views
Cisco 2960-X IOS Version 15.2 can't use command access-session control-direction both
I am trying to configure a Cisco Switch 2960-X with IOS V15.2 for WOL ( Wake on Lan)
I tried this tutorials but the command isnt working:
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/san/command/...
- 1
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votes
0
answers
76
views
Hide FTP login details from the running config
We are using the below commands to save configs onto an FTP server, I am wondering if we can hide the login details as they show in clear text in the running config.
#show run | b archive
archive
...
- 383
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votes
1
answer
594
views
Warning: portfast should only be enabled on ports connected to a single host
I've got this error and feeling frustrated about it , So we have in Production areas machine that's needs to assign to vlan 213 and after i did the configuration for that port and got an error with ...
- 41
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1
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372
views
What does `action errdisable` do differently when issuing `power inline police`?
While learning for my CCNA exam, I was looking over Cisco's PoE guide. It explains how to configure PoE so that a port changes its behavior when a device draws too much power:
power inline police: ...
- 113
2
votes
1
answer
463
views
How do you drop (or ignore or filter) all untagged traffic on an 802.1q trunk port?
This answer says "[a] trunk has optionally one untagged VLAN and many tagged VLANS."
I always thought specifying switchport mode trunk would drop untagged frames at that port, but that ...
- 157
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votes
1
answer
59
views
Is it risky to change hardcoded STP mLAG port cost on Cisco Nexus LACP port
When two Cisco Nexus are connected in VPC, the stp cost is hardcoded to 200 for the mLAG LACP ports.
I would like to manually change the cost on my devices because my 2G and 200G links have the same ...
- 123
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435
views
Cisco router access list not working as expected
I'm trying to set up a network in packet tracer with inter-VLAN routing. I need to restrict one of the VLANs to only accept traffic from the 172.25.30.0/24 network.
To do this I am using an access ...
- 3
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votes
3
answers
369
views
What does `switchport trunk native <n>` do when in `switchport mode trunk`?
According to this article Cisco recommends VLAN 99 for the "native VLAN".
But what is the point when operating under switchport mode trunk?
Doesn't switchport mode trunk filter all tagged ...
- 157
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votes
0
answers
28
views
Network Tapping cat3750/3850
I work with tapagg solutions as an NDR engineer. Upgrading my lab for various reasons. Right now I SPAN with an old cat2960 into my packet system. I need to bump up to gig span and would like some 10G ...
0
votes
1
answer
952
views
How to generate cisco key-hash string
cisco IOS stores public keys used for authentication as hashes.
cisco obviously does not store the key itself because you can simply copy these key-hash lines between machines and you can authenticate ...
- 153
0
votes
1
answer
72
views
Why I’m getting overlaps with fast Ethernet 0/1 when assigning an ip
But I have been receiving error code when I want to assist an ip to s1/0
2
votes
2
answers
307
views
spanning-tree portfast
IF I remove vlan 922 do I still need to have spanning-tree portfast when I will assign this port to UPS? I just need a port setup without voice VLAN and in layer two network
interface GigabitEthernet2/...
- 41
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votes
1
answer
171
views
I got locked out of my switch
I am currently practicing on cisco packet tracer, so I used the command " enable password 5 cisco"
then I leave the global configuration mode to the user mode and try to go to privilege mode ...
-1
votes
1
answer
64
views
aggregating Cisco 2960 ports with Cisco 3850
I'm new to networking. I have two switches: Cisco 2960 & Cisco 3850. I want to connect 4 Trunk ports of these switches to each other. Since Cisco 2960 port speed is 1G and Cisco 3850 is 10G, I ...
- 1
1
vote
1
answer
138
views
ISR 4331 vs ISR 4331/K9?
We have cisco router. On its box/package ISR 4331/K9 is written. I am watching a youtube video at below link, its title has word ISR 4331
https://www.youtube.com/watch?v=bk-4jkb6Cwo&list=...
- 111
1
vote
1
answer
104
views
Cisco Switch login
I have a switch as connected to the stack. I got it off the internet so now I need to login to this switch. I connected it to my laptop by the console cable and it did not let me to login with my ...
- 41
0
votes
1
answer
33
views
why SR LSP no tunnel interface? but SR TE need it?
I'm a bit confused that why SR LSP(or LDP LSP) no need to config a tunnel interface, but SR TE(or MPLS TE) need it.
how the tunnel interface works?
- 3