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ping layer 3 switch and hosts

Posted on 2013-12-31
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Last Modified: 2014-01-08
I have a lab with different networks and on one network I have a layer 2 and layer 3 switch, the layer 3 switch is connected to a router. I have a few different vlans on this network. All vlans can communicate with each other and the switches and router.

I can ping externally to another client on another network form the layer 3 switch with no problem. However, I cannot ping from the layer 2 switch or computers on the vlans on the same network to these external hosts. What is it that is preventing replies when I ping externally?
There are no acl's on the routers.
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Question by:tolinrome
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Expert Comment

by:Trenton Knew
ID: 39749125
is the switchport access mode to the router a trunk or is it only assigned to one vlan?  If the layer 3 switch is not routing inter-vlan traffic, the port connected to the router will have to be trunked, and the router itself will have to support inter-vlan routing and trunking.
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Expert Comment

by:Trenton Knew
ID: 39749129
are there multiple vlans on the layer 2 switch also?  is the switchport access mode between the port on the L2 switch and L3 switch trunked as well?
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Expert Comment

by:jburgaard
ID: 39749166
Best gues is a missing route back on router to vlan with problem.

But please provide details: IP, dgw. and net-mask for a client with problem.
For L3-switch: IP & net-mask for involved vlans and dgw.
for router:IP & net-mask for involved vlans and IP routes back to client-network.
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Author Comment

by:tolinrome
ID: 39749179
L3 switch is the DG for the vlans, I set up int vlans XX on it as below:
10.1.10.1
10..120.1
10.1.30.1 and etc

L2 switch has these vlans as well (obviously not int vlans, just vlans). host computers are connect to the L2 switch only.
On the L3 switch there is the "ip routing" command for internal vlan routing and the statement "ip route 0.0.0.0 0.0.0.0 10.1.60.2" which 10.1.60.2 is the internal interface of the router. Vlan 60 is the vlan that connects the L3 switch to the router. It is only 2 interfaces, the L3 switch and router.
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Expert Comment

by:jburgaard
ID: 39749223
So you have a number of networks with net-mask 255.255.255.0
your dgw of L3-sw is 10.1.60.2
For packets to come back from your router there must exist 'routes back' like
IP ROUTE 10.1.10.0  netmask 255.255.255.0  gw 10.1.60.1
The syntax probably is not exact , but to reach an address in the 10.1.10.0/24 range a packet arriving at router has no directly connected network to turn to and should not go via dgw (to internet) but via L3-switch.
Instead of a lot of routes like that you probably can bundle them with a broader net-mask than 255.255.255.0
HTH
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Author Comment

by:tolinrome
ID: 39749375
I already had "ip route 10.1.0.0 255.255.0.0 10.1.60.1" and it wasn't working and now I added:
R1(config)#ip route 10.1.20.0 255.255.255.0 10.1.60.1
R1(config)#ip route 10.1.30.0 255.255.255.0 10.1.60.1
R1(config)#ip route 10.1.10.0 255.255.255.0 10.1.60.1
R1(config)#ip route 10.1.40.0 255.255.255.0 10.1.60.1

and it still doesn't work.
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Expert Comment

by:jburgaard
ID: 39749833
Could a there be a firewall-rule on the destination PC?
Did you try disable firewall or pinging printer instead of PC?
Did you try traceroute/tracert both ways?
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Accepted Solution

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tolinrome earned 0 total points
ID: 39749945
Problem solved. On the L3 switch, not the router, I had to use the "#network 10.1.x.0 0.0.0.255 area 0" for ospf, which then relayed those networks to the router and so on.
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Author Closing Comment

by:tolinrome
ID: 39764692
This was the solution.
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