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Cisco 3750 switch cannot route across vlans

Posted on 2012-03-20
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Last Modified: 2012-03-26
Hey there,

I have three cisco 3750 switches configured in switch stack with 2 vlans (one voice, one data) on a network with about 9 vlans.  The issues I'm having is that the users from 172.16.9.x network cannot contact the phone server on 192.168.10.x network.  Packets are hitting the swith but everything is being sent out the gateway including phone server packets.  I have setup port monitoring and changed the users gateway to the switch and still no luck.  Is there some way to accomplish this without a third party device (router or firewall)?  Is some kind of trunkng possible?  I can post the configs if you need them.  Please help!  thanks.

static route:  
 The switch IP is : 172.16.1.2  
The switches gate:  172.16.1.1

Users are on 172.16.9.x
IP phone system in on 192.168.10x
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Question by:metalfubar
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by:ryan80
ID: 37743191
did you put in

ip routing

to enable routing?
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Expert Comment

by:raeldri
ID: 37743250
like ryan mentioned is ip routing enabled. you mentioned the 3750 has 2 vlans does it know how to reach the other vlans?

ip route 192.168.10.0 255.255.255.0 (router/switch IP to reach network)
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Expert Comment

by:abhishek1986
ID: 37743721
In configuration mode, apply the command to apply routing
Cisco3750(config)# ip routing

Then check if the show ip route command shows all the VLans in the routing table
Cisco3750# show ip route
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Author Comment

by:metalfubar
ID: 37743959
so if I type ip show ip route it displays only my vlans on the switch (192.168.10.0/24 and 172.16.0.0/12.  Does this cover all vlans?  if not, can i add them invidividually somehow?

thx
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by:ryan80
ID: 37743979
You are just using the subnet of 172.16.0.0/12? Even on the computers?
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by:raeldri
raeldri earned 250 total points
ID: 37744035
the switch doesnt need to be aware of all Vlans but its default route should be or they need to be manually defined.
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Author Comment

by:metalfubar
ID: 37744235
does the gateway of the phone vlan need to be included here?  what about a static route to 172.16.9.x for the users?

ryan:  yes 172.16.0.0/12 for all subnets except the 192.168.10.x.
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by:raeldri
ID: 37744255
the switchgateway (172.16.1.1) should know how to reach the 192.168.10.0 network if it doesn't. you need to add a route to the switch with a next hop address that will get it closer to the 192.168.10.0 network. the 192.168.10.0 network also needs to know how to get back to the 172.16.x.x networks. do you have a network map you can share so we can provide additional input
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Author Comment

by:metalfubar
ID: 37744401
actaully yes, the switch vlans are communicating and can ping each other fine.  192.168.x - 172.16.x.  so yeah, if a user on 172.16.9.x tries to connect their ip phone 192.168.10.x it does not work.  when typing:

ip route 192.168.10.0 255.255.255.0

I do get an invalid input error detected.
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ryan80 earned 250 total points
ID: 37744452
you need to put in the gateway ip address for the ip route command.
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by:abhishek1986
ID: 37745764
You need not give any routes for this communication.
If the two VLANs are attached to the same switch, they will be communicating.
Just check in switch the output of
Cisco3750# show ip route
If it shows you two connected networks, namely, the 172.15. Network and the 192.168. Network and a Default route, 0.0.0.0/0 via x.x.x.x, then all are fine.
In show run, do you see, IP routing enabled.

Follow this link for more clarification:
http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a008015f17a.shtml
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