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.
3,759
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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 ...
- 2,040
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2
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60
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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
...
- 82.6k
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122
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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 ...
- 82.6k
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132
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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 ...
- 67.1k
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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::/...
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1
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2
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3k
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Cisco ASA VPN disconnecting regularly random time
We have Cisco ASA VPN IPSec with Sonicwall but we are seeing randomly after 8 hours or sometime 10 hours. I am unable to trace issue so just wonder is there a simple setting to renegotiate tunnel ...
- 2,040
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28
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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 ...
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1
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794
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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/...
CommunityBot
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2
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3
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747
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Cisco 2960 not receiving dhcp from the router
I have a problem with Dhcp of some the Vlans. here is how my network is :
I have a router ASR1001, which connects 15 switches(2960) as a ring topology. each switch has a subinterface of the router ...
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1
answer
2k
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Cisco ASA IPsec tunnel QM FSM error
I am setting up Cisco 5585 ASA for IPsec tunnel with one of cloud company.
we already have lots of tunnel for various cloud provider and life if good but recently this tunnel giving me hard time to ...
CommunityBot
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0
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91
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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 ...
- 82.6k
2
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3
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2k
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NIC transmission is serial or parallel
Since NIC card receives data from memory in parallel, does it perform the transmission over the link serially? if yes, how?
Thank you.
- 82.6k
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2
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217
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How does distance play a role for total transmission time?
I've found a similar question in this site but the answers were not convincing me enough so I'll make a small scenario of two routers to express my point:
Two routers connected by a link of rate 1 ...
- 13.1k
1
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1
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185
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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 ...
- 19.5k
1
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1
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64
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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...
- 2,040
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1
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50
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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 ...
- 82.6k
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3
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125
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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 ...
- 55
2
votes
1
answer
602
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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 ...
- 2,040
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157
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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....
- 82.6k
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1
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565
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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 ...
CommunityBot
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38
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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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154
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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 ...
- 2,638
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2
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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?
- 2,040
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1
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28
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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 ...
- 2,040
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238
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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: ...
- 988
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votes
1
answer
109
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Cisco C9300 Drop Out And VLAN Table Loss
I have a Cisco C9300 is one of my main racks. Recently it has been restarting on it's own. My suspicion that the PSU is on the way out. Strange part is when it does this the VLAN table resets to ...
- 461
1
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2
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540
views
Cisco ISR 4000 series with SM-X Layer 2/3 module
I have a Cisco SM-X-16G4M2X Layer 2/3 Service Module installed in an ISR 4000 series router, and I would like to configure its ports as level 2 in a vlan, and then configure that vlan with an IP ...
3
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1
answer
328
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Cisco IP Fragments ACL strange behavior
I am testing following ACL on Cisco 3850 L3 switch :
C3850#show ip access-lists 101
Extended IP access list 101
10 deny ip any any fragments
20 permit ip any any (268 matches)
I applied ...
- 98.7k
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2
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396
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Unable to ping but I can see the arp in switch 4451
Recently I got to know that I am unable to ping the IP addresses behind vlan236 from core1 whereas I am able to ping the same from core2 and able to ping the IP address of vlan236 from my laptop as ...
CommunityBot
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1
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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 ...
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2
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278
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How to link three Cisco 2960 switches together?
Current Network Setup
I have three Cisco 2960 switches. Each switch linked to a lab of 12 windows 10 computers. All three switches are in the same cabinet.
1st switch connected to 2nd switch using the ...
- 2,040
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2
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2k
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Cisco performance issues C890 series
I'm working on a complex project that includes Linux and Cisco routers. I am fairly new to networking and i'm using cisco command lines for the first time, so please be nice and don't hesitate to ...
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7
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2
answers
528
views
Where is the traffic going?
Here is a routing puzzle:
I'm working on a poorly documented network, and I'm trying to document things as I discover them.
R1 is a core L3 switch. R2 is a router. The FW is a, well, firewall.
On ...
- 68
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2
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225
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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 ...
2
votes
2
answers
390
views
Spanning tree loop prevention
Can I get some advice on what STP features to enable as best practice please, mainly to mitigate loops? In the past a user mistakenly connected two floor ports together causing a loop.
Below are the ...
CommunityBot
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1
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317
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 ...
CommunityBot
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1
answer
145
views
I upgraded a Cisco switch to a newer model with different SNMP OIDs. Can I have the new switch receive the old OID and report values from the new OID?
I upgraded from a Cisco SG300-10MP to a Cisco SG350-10MP. A piece of software is looking for the value from 1.3.6.1.2.2.1.8.50, but the OID on the new switch is 1.3.6.1.2.2.1.8.2. The final number ...
CommunityBot
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votes
2
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61
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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 ...
- 31.7k
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653
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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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1
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530
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
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0
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891
views
IKEv2 between Cisco router and Google cloud VPN
Hey I'm trying to create a tunnel between cisco router and google cloud vpn (client site) but the connection is stuck on stage 2 (UP-IDLE), need help where the problem may lie.
Some debug that I get ...
1
vote
0
answers
95
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
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1
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1k
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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
...
- 98.7k
0
votes
1
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94
views
Dell OS10 equivalent of Cisco switchport access
hoping someone knows OS10 command structure :)
In the Cisco world, if I want to create an access port and add it to VLAN 50 its simply:
switchport mode access
switchport access vlan 50
What would the ...
CommunityBot
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1
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268
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 ...
CommunityBot
- 1
1
vote
4
answers
414
views
Cisco Core Switches - Identifying unused ports
I've started at a new site, and the server room is an absolute state - I want to get in and start removing unused patch leads, so that I can start to see what is available & to tidy up.
There is ...
- 19.5k
2
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2
answers
5k
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How Can I configure DHCPv6
I want to config one DHCPv6 server using Packet Tracer and with multiple routers, the router takes IP addresses from a server and distribute to computers .I have done that with IPv4 using IP helper ...
- 98.7k
3
votes
2
answers
3k
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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 (...
- 205
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1
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320
views
Cisco ASA 5516-X won't communicate on inside interface at all. No packets
I'm configuring a brand new ASA and the Firewall refuses to communicate on my inside interface.
No matter the traffic type, its denied by implicit deny every time. I was hoping to get some feedback/...
CommunityBot
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2
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230
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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