cannot ping pc to server-pt

[lizel]

I can't ping the lower pc from the server on each switch. The upper pc on each switch can be pinged from the server but the other one won't ping. What's wrong here?

[Martin L · Accepted solution]

Missing are default gateways on PCs; those are use  to go outside of local LAN; And, you do not have any routing set up; To route between networks u need a router or L3 switch; Using a router is called ROAS, router-on-a-stick.  you can find several examples here posted by others PT users.

Regards, ML
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[M02@rt37 · Accepted solution]

Hello @lizel 

Upper PC can be pinged from the server because there are on the same subnet. Lower PC is an other subnet, then you need to add Gateways on PCs and servers.

BUT, beause you are using Switch you cannot perform routing between subnet (inter vlan routing). You need a router to perform routing! Use Router On a Stick: https://www.grandmetric.com/knowledge-base/design_and_configure/router-on-a-stick-approach-cisco-configuration/

Or easy way, use a L3 Sw like 3560 instead of 2950 in order to do inter  vlan routing.

[lizel]

if i use L3 switch, do i still need to include a router? and all of my PCs and servers are on the same subnet (255.255.255.0) so what do you mean by my lower pc is on other subnet? and what does the default gateway have to do with it?

[M02@rt37]

@lizel 

if i use L3 switch, do i still need to include a router? No

and all of my PCs and servers are on the same subnet (255.255.255.0) so what do you mean by my lower pc is on other subnet? I remember that lower PC is in an other subnet...

and what does the default gateway have to do with it? Default Gw on PC in order to send its packet to a L3 device to communicate with others known subnets.

[Martin L]

Every time u want to go to www, email, etc, your PC checks destination IP, then mask. It will compare values like source IP and mask to destination IP to figure out whether u wanna go outside local subnet/vlan or stay inside local subnet. aka, local or remote location. If it's local, ARP is performed and packet is build. 

If your dest. IP is not on local network, then PC checks for default gateway (your L3 switch or router).  It will contact L3 device to build ARP then send packets to L3 who -in turn- checks its routing table for dest. IP. and moves /forwards packets to its next hop. And so on till u get to dest. IP.   Basically default gateway L3 device is responsible for routing packets between remote locations.

if you do trace route to cisco .com, you can see hops and IPs which are L3 devices.

Regards, ML
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