Questions tagged [troubleshooting]
For questions requiring troubleshooting assistance with persistent/unresolved problems.
150
questions
0
votes
1
answer
90
views
Wireshark filter for specific SYN packet which never received a SYN/ACK
Is there a way in wireshark to find out a single SYN that does not get answered by SYN/ACK?
- 893
1
vote
1
answer
73
views
Troubleshooting network issues; General inquiry
I work as a junior network admin at an ISP and I would like your help in resolving an issue whose cause is not readily apparent. Rn I am trying to troubleshoot a case where a switch interface randomly ...
0
votes
2
answers
39
views
Trying to achieve ECHO request reaching destination in other VLAN
I'm working in a network on packet tracer, when I'm sending ICMP requests from VLAN 20 (yellow field) to VLAN 10 (turqoise field) the packets get stuck at the switch where it is connected to.
Case 2: ...
- 3
0
votes
1
answer
29
views
Do wiremap testers detect split pairs
I was watching a How-to video on Youtube on wiremap testers and the technician said that wiremap testers detect split pairs among other wiring faults. However, I came across a Networking question ...
0
votes
1
answer
223
views
How to determine if a network cable is bad on a LAN under an unmanaged switch with no DHCP?
Is there anyway to detect this via automation and software? I know if I can get access to the MAC address table on the switch I can see if there's a missing MAC address. I don't know if this is ...
- 103
0
votes
0
answers
266
views
Eigrp flapping while using natting with route map
I have configured a topology which contains ip sla , route map , dual natting.It work perfect but when I used route map natting the eigrp become flapping and show the error is "retry limit ...
0
votes
0
answers
35
views
Cisco Kron Job starts later and later
I use a Kron job to ring a shit bell for our manufacturing plant. The application works, but the job starts 35+ seconds late. The problem seems to be getting worse, a few days ago it was at 35 secs ...
2
votes
3
answers
1k
views
How can you determine the result of a load-balancing hashing algorithm (such as ECMP/LAG) for troubleshooting?
In many architectures there are load-balancing mechanisms such as ECMP routing or LAG between various interfaces. This load-balancing is usually per-flow, based on a hash of various criteria, such as ...
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0
votes
1
answer
366
views
Does Telnet need to be activated on both devices I am using or not? [closed]
I've searched everywhere for the answer to this question but can't find a simple yes or no.
Basically, I have a virtual server hosting some services and then a physical panel PC in another part of the ...
1
vote
2
answers
65
views
Steps on troubleshooting a network
If I have to troubleshoot a network stating that one of the interface is
not working (i.e, a link is down), what steps would I need to take to make it
working again?
- 127
0
votes
0
answers
370
views
NAT overload and access to web resources
I have really bizarre problem in clients network.
Clients have access to the internet via NAPT - I'm using several public ip addreses for this purpose. (I'll change ip addresses for obv reasons)
ip ...
- 45
5
votes
2
answers
120
views
Cisco 2821 hangs with "No memory"
I have one (pretty old) 2821 router, running BGP with 2 ISPs.
(C2800NM-ADVENTERPRISEK9_IVS_LI-M), Version 12.4(24)T5
Sometimes for unknown reason it just hangs, and as it is remote location I cannot ...
- 51
6
votes
1
answer
963
views
Bandwidth limit Cisco 3400 ME problem
I want to limit bandwidth (speed) of interface of Cisco 3400 ME switch.
I did these:
policy-map parent
class class-default
shape average 64000
And in gi0/2 interface I apply it: service-policy ...
- 203
2
votes
0
answers
2k
views
Point to Point ICMP Ping Loss between Juniper MX routers
I am facing problem with regard to 1 x 10G link (which is actually configured as an aggregated Ethernet (ae) i.e ae link contains only single 10G link.
This ae link is connected between 2 x Juniper ...
- 1,110
2
votes
1
answer
57
views
How do I find out which NAT is getting hit?
I can see in packet captures that my packet's destination IP is getting translated. How do I find which NAT statement is responsible for the conversion if my device has over 200 NAT rules? I'm using ...
- 55
1
vote
1
answer
1k
views
Cisco 49XX multicast flooding
I have problem with multicast on cisco 4948.
I've got vlan 9 with muilticast, which configured on several ports. Switch floods multicast traffic on all ports configured with vlan 9. It consumes link ...
- 123
3
votes
1
answer
2k
views
Cisco Router IOS update
I am facing problem in update the IOS of Cisco 7304 router. I am upgrading from 12.4(24)T2, to 15.2(4)S7 this. but I was boot from this version 15.2(4)S7 it booted proper from flash. But when I put ...
- 53
0
votes
1
answer
4k
views
How to Troubleshoot Network Latency Step by Step
Does anyone have an idea of how to troubleshoot high network latency step by step?
For example, let's say we have a remote office. And all users are from that office are having high latency accessing ...
2
votes
1
answer
261
views
Routing and Switching & network monitoring
hi i am facing problem in juniper switch Model: ex4200-48t ,Junos: 15.1R6.7 . i deploy network monitoring check-MK software. there is showing errors of juniper switch ports and also show in logs file ...
- 53
4
votes
2
answers
398
views
PAT not translating at all
I am studying for my CCENT.
I threw together a PAT practice lab.
Other than DHCP and RIP everything is pretty stock.
No VLANs
No security
Just NAT overload on ACCESS router.
I am stumped why it isn'...
1
vote
0
answers
37
views
Troubleshooting slow connections in large data centers [closed]
I’ve been asked this question - or a variation of it - during some recente job interviews. I think my answers were adequate (involving reducing scope, packet tracer with many probes, etc) but I’m ...
- 11
1
vote
2
answers
444
views
What can I infer about a network connection using a cable tester (if anything)
I have a NS-468 cable tester for testing cables. This works fine but if I connect just one end of a RJ45 cable to a network, I only get 4 lights. This seems reasonable as I suppose 4 pins are for ...
- 125
3
votes
1
answer
2k
views
Fix our Cisco switch overwhelmed by console logging
I have a setup with dual redundant Cisco catalyst 4506-E using the WS-X45-SUP8L-E supervisor engine and two 48-port switches below it.
My task is to access and modify the switch configuration.
...
- 33
1
vote
0
answers
74
views
Internet not working [closed]
I have this types of network in my office. Recently we have moved to new i BSNL internet.
My problem is when i bypass router and connect poe cable to computer internet is working but when i put ...
1
vote
1
answer
575
views
Cisco: Router can ping Internet, Clients cannot
I'm currently playing around with a Cisco 819 LTE-integrated (C819G-4G-G-K9) router at my summer place to get a better LTE-signal and control that the ISP router provides me.
Currently I'm stuck at ...
- 13
2
votes
1
answer
1k
views
Intermittent periods of high packet loss, one hop beyond router
I've been trying to diagnose internet connection issues at a remote small business for which I am the system administrator. If this is not the proper Stack Exchange to post to, I'd really appreciate ...
- 21
2
votes
1
answer
818
views
arp or proxy-arp causing high cpu
We have an issue on a Cisco A901-6CZ-F-A with high cpu caused by Arp requests coming on Vlan11 from our customer.
We enabled 'debug arp' to try and diagnose, below is a small snippet.
IP addresses ...
- 480
0
votes
1
answer
78
views
What are the "next steps" to take when business Internet service stops working? [closed]
Scenario (based on real events)
a small business has a "BigCorp" Internet service. One day the Internet goes down after a power outage, and they call BigCorp for help. BigCorp support over the phone ...
- 103
1
vote
2
answers
155
views
Cat 5e wiring Type A incompatibility with Type B
I am not an engineer but I’m having problems with my small network in my business. I have 11 computers after 13 yrs am having major problems. My network keeps shutting down, and my dental software on ...
- 11
0
votes
2
answers
699
views
Do I have to reboot the Fortigate 1000c after modification on static route?
I am using a Fortigate 1000c working on NAT mode. It has two WAN connections (WAN1 and WAN2). I am using a static route.
For some reasons, There are many firewalls and routers (Cisco, TP-Link and so.....
2
votes
2
answers
806
views
ASA not passing traffic
I hate posting things like this, but we're backed into a corner here. We recently had a new client ask us to set up an ASA for their branch office 800 miles away. A colleague and I spent last night ...
- 31
1
vote
2
answers
1k
views
Poor bandwidth after re-coupling an Ethernet cable
As part of an experiment I cut a Cat 5e Ethernet cable in half, stripped off a small amount of insulation on each wire and attached each pair of wires together with its own alligator clip.
There are ...
- 253
1
vote
1
answer
2k
views
Can't connect to FTP [closed]
I am using Beetel 777VR1 with Airtel Broadband. I am trying to connect with a FTP server but I am not able to access that. However with same credentials when I try to connect with my mobile ...
- 113
2
votes
1
answer
2k
views
how to capture only SMTP using latest Wireshark 2.2.6 or later
I am debugging a problem with my Azure VM Windows server receiving SMTP from the Internet, and want to use Wireshark to show ONLY SMTP.
I would also like to use Wireshark to show the contents of the ...
- 121
3
votes
1
answer
2k
views
Adding encrypted password on Cisco 3560-CG switch
I'm trying to update the enable secret and account password on a Cisco3560-CG switch with an encrypted password shared by devices throughout the company. I use the following command for the enable ...
- 33
1
vote
1
answer
96
views
Consistent no route to host errors on servers
Servers configured with DHCP have a default route in the corporate network. Every time a "new" host is connected, a "no route to host error" is received. The second request after a few seconds works ...
- 113
1
vote
1
answer
727
views
Help me understand this netstat report
I am IT admin, and I got this report from a user.
Can you help me understand the TCP connection entry to to this doubleclick Foreign Address? Is it a concern for the end user/organization? What could ...
- 113
1
vote
1
answer
1k
views
DMVPN Tunnel Spoke sending registration requests but Hub does not get it
I have built a topology in GNS3 with five routers with a goal to perform:
1)inter vrf routing with bgp as the routing Protocol between Routers.
2)build DMVPN tunnel on the top of it.
I was ...
- 13
1
vote
2
answers
719
views
How to verify Voice QoS dscp and IP predecence traffic session?
How can I verify tht QoS is working for voice traffic? I also have voice server IP address. Can I also know what the session source/dest/port number info?
class-map match-all avaya
match access-group ...
1
vote
2
answers
255
views
Time exceeded ICMP in Serial Interface [Cisco Router 2811]
R1 and R2 are the same network.
But when you send a check to the ICMP Ping output "Time exceeded" error and,
show interface Serial0/0/0
command produces the following output:
Serial0/0/0 is up, ...
1
vote
1
answer
1k
views
Juniper EX4200 firewall filter applied to trunk port not matching specific VLAN
EX4200 switch has a firewall filter applied to input of trunk port.
Intent is to rate-limit (police) input bandwidth per VLAN id.
However the 'show firewall' command points out that policing is ...
- 1,636
1
vote
1
answer
71
views
Cisco AIRONET 700 loses connection while downloading
We have three of them, but one is messing around. As soon as you download a bigger file, he loses connection. I can't ping the AP (from another PC connected via LAN), and the PC connected via Wi-Fi ...
- 363
2
votes
2
answers
293
views
Cisco CoreSwitch 6509 Vlan connection problems
just wanted to ask what measures I'll have to do regarding on my problem on CoreSwitch 6509.
I have 12 vlans on layer 3 switch which has 48 ports, 4 ports per vlan and I have a backbone on vlan 10 and ...
- 31
3
votes
2
answers
316
views
Cisco ASA 5505 ver 8.2 Firewall
I am working on a project to allow ICMP through the firewall from the outside interface to an inside interface.
I have configured the firewall to inspect icmp and allowed icmp through access-list ...
- 56
0
votes
1
answer
2k
views
Is there a way to automatically have unused ports disable?
Like many others I can see how to display ports that have no traffic flowing through them and go through and disable them but we have hundreds of cisco switches.
I like the idea of being able to see ...
- 21
1
vote
2
answers
333
views
Cisco 1800 series: sys-2-chunkexpanfail: error every time
My knowledge of Cisco is very basic and I´m having this error constantly. I have to reboot every time, and it does not seem right. How can I solve it at once?? What I know of this device is that it ...
1
vote
1
answer
874
views
Which is the actual TCP MSS for this iBGP connection on ASR9K running IOS-XR?
I have this iBGP session established between a Cisco ASR9K and a Cisco 7600 router.
On the ASR9K device, 'show tcp detail pcb all' displays 'MSS 1240, peer MSS 9152, min MSS 1240, max MSS 1240' for ...
- 1,636
2
votes
1
answer
204
views
Can't copy files within ERX
I use FileZilla FTP client to connect to my equipment in order to get files from there. I tried same process in my ERX, without success.
Below is a view of my directory
bras-2.cm#dir
Please wait...
...
- 129
1
vote
1
answer
762
views
How to collect core dump files in Juniper ERX
For troubleshooting purposes, I need to collect some files from my ERX.(by ftp)
Below is the content of my directory
ERX#dir
*** Active/standby file systems are being synchronized. ***
...
- 129
2
votes
0
answers
980
views
Problems connecting to clientless vpn portal on a Cisco ASA 5505
Just started a job where they wanted us to re-purpose a local network that wasn't in use and to create a webvpn portal to allow web access to it. We've tried everything and looked every where and ...
- 21