NETWORKING BASICS

[KARTHIKEYAN.K]

NETWORKING BASICS

[deanwebb]

I guess one would start with "always check the temperature and ventilation in the network closet".

[that1guy15]

plug both ends of the wire in.

[deanwebb]

plug both ends of the wire in.

And take notes. When you see this again, look for the wire with both ends plugged in. Maybe it will take you less than the 12 hours it took to solve when it happened to me, 4 years ago...

[icecream-guy]

if in doubt - reboot it.

[Otanx]

I would go with


or


-Otanx

[deanwebb]

Agree strongly with Otanx and Ristau. There's a reason those images are in our smiley bank.

Another basic: replace "definitely" with "probably", "always" with "usually", and "that can't possibly happen" with "let me check those settings one more time."

And, if the developers put the network together:

[wintermute000]

[dlots]

Is the device you can't ping in the arp table of it's default gateway?
If yes can the default gateway ping it?
If no that means it's almost always a firewall on the end device.

I really really really wish someone had introduced me to the ARP table and explained how awesome it was for troubleshooting when I 1st started in networking.

[LynK]

yes... systems team. The default gateway does matter.

[that1guy15]

yes... systems team. The default gateway does matter.

I have had this conversation way more than I should:

SysAdmin: I cant reach serverX from interface B but can from A
Me: You dont have a route point out B to get there and its following DG out A.
SysAdmin: But both interfaces have a DG set.
Me: Only one gets used. You will need to set static routes.
SysAdmin: Cant you change the network to allow this? I dont know how to set routes in Windows
Me:...

[LynK]

yes... systems team. The default gateway does matter.

I have had this conversation way more than I should:

SysAdmin: I cant reach serverX from interface B but can from A
Me: You dont have a route point out B to get there and its following DG out A.
SysAdmin: But both interfaces have a DG set.
Me: Only one gets used. You will need to set static routes.
SysAdmin: Cant you change the network to allow this? I dont know how to set routes in Windows
Me:...

LOOOL!!!!!!!

AHAHAHA... that is fantastic. I am glad I am not the only one. I have had this exact issue before.

It gets even better, at my old job we were having an issue with one of the dell chassis, and They kept blaming it on the nexus and its issues. I told them to go in and clear the arp cache on the controller... they snuffed it off as meaning nothing. The next day a sysadmin came over and told me I fixed YOUR issue by clearing the ARP on the chassis. I almost died... hahaha

[SofaKing]

yes... systems team. The default gateway does matter.

follow this with -
yes... systems team.  The subnet mask does matter.

[SofaKing]

And, if the developers put the network together:

When you say "it" I hope the developers are included 

[deanwebb]

And, if the developers put the network together:

When you say "it" I hope the developers are included 

Thanks for the feature request, I'll take it back to the BU.