09-24-2008 01:05 PM - edited 03-06-2019 01:34 AM
Hi, based on:
http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a00800949fd.shtml
A little progress, the trunk is nearly working I think, but both PC's can't ping each other.
I have a PC (PC A) with:
IP address - 192.168.2.50
Gateway - 192.168.2.1
In FE 0/9 of switch VLAN10
I have a PC (PC B) with:
IP address - 192.168.3.10
Gateway - 192.168.3.1
In FE 0/17 of switch VLAN20
PC A can ping 192.168.2.1 and 192.168.3.1
PC B can ping 192.168.3.1 but NOT 192.168.2.1
What could this be?
Solved! Go to Solution.
09-25-2008 11:29 AM
Hello Andy,
I was meaning
sh int fas0/1 switchport
Excuse me for not having typed an enter before.
I got it :
no ip routing
in the router config
you need to turn ip routing on the c2600
conf t
ip routing
Hope to help
Giuseppe
09-24-2008 01:18 PM
Hello Andy,
I've never seen this to work:
interface FastEthernet0/0.10
encapsulation dot1Q 10
>>> ip address 192.168.2.1 255.255.255.0
no ip route-cache
no ip mroute-cache
!
interface FastEthernet0/0.20
encapsulation dot1Q 20
ip address 192.168.3.1 255.255.255.0
no ip route-cache
no ip mroute-cache
!
interface FastEthernet0/0.100
encapsulation dot1Q 100
>>> ip address 192.168.2.98 255.255.255.0
no ip route-cache
!
how can two subinterfaces have overlapping IP addresses ?
have you tried this config ?
you should get an error for the second one you try to add
192.168.2.1 and 192.168.2.98 are in the same subnet
I would suggest you to use a one to one corrispondence between vlans and IP subnets.
about PC B:
verify it has the correct gateway (192.168.3.1)
Hope to help
Giuseppe
09-24-2008 01:28 PM
Hi,
I did let me add these 2 sub interfaces. Anyway I have removed interface FastEthernet0/0.100 and checked the gateway is correct too as I can ping 192.168.3.1 from PC B, still the same problem. PC B cannot ping 192.168.2.1 or PC A but can ping the subinterface of 192.168.3.1.
Does the switch need a default gateway?
09-24-2008 04:25 PM
The default gateway on a layer 2 switch is just to be able to manage the switch from a different subnet than the mgt. vlan is on , has nothing to do with any devices attached to it . Do you have the same native vlan on both the router which appears to be vlan 1 and the 2950 ? On the router try
interface FastEthernet0/0.10
encapsulation dot1Q 10 native
on the switch connection
try
switchport trunk native vlan 10 .
09-24-2008 10:00 PM
I'm a little confused here. I haven't done anything with the native vlan 1 as I didn't think I was using it, why do I?
Also you only mention adding it to vlan 10 and not 20.
09-24-2008 06:36 PM
Have you thought that there may be a personal firewall on PC A, preventing PC B from pinging it?
Ive seen that many times before.
OR
PC A has a route table configured on it and does not have a route for hosts outside its local subnet, or no route back to PC B's subnet.
Seen that a zillion times, too.
Thanks
Victor
09-24-2008 10:11 PM
Hi, the 2 laptops seem fine, if I put them in the same vlan using the same IP range then they can ping each other. I did a route print on their command prompt as well and there are no addition persistant routes.
Someone has mentioned I need to add the native vlan to the trunks, what is this native vlan used for?
09-24-2008 10:52 PM
Hello Andy,
in an 802.1Q trunk the native vlan is the only vlan that have its frames sent untagged = without an header 802.1Q.
It is thought to provide backward compatibility to NICs that are not able to use and understand 802.1Q tagged frames.
A mismatch in native vlan can cause IP connectivity issues:
if one trunk side thinks that native vlan is x and the other side thinks is vlan y untagged frames from vlan x are sent and the other side treats them as frames in vlan y and tries to forward them in its vlan y's ports.
In your case I would point to the GW config of the second laptop if it is wrong or missing it could be unable to reach ip hosts in different subnets.
Also Victor's suggestion is good : many and many times users complain of ip connectivity and they have a sw firewall running on the PC.
Here native vlan should be the default one that is 1 but it is not permitted on the trunk on the switch side.
Hope to help
Giuseppe
09-24-2008 11:46 PM
Hi,
I replaced the laptop with a router with an IP of 192.168.3.10/24 and ip default-gateway of 192.168.3.1 and I get the same problem.
Do my configs look good and do I need to add the native vlan 1 to the router? If so do I add it to all subinterfaces?
Thanks
09-25-2008 12:24 AM
If you don't add the native vlan to the router it is a default of 1 just make sure the connecting link on the 2950 side is also 1 , if you haven't changed it then it should be 1 by default also , just look at the config on the switchport if it doesn't have a "switchport trunk native vlan X" command then it is 1 by default.
09-25-2008 01:04 AM
Thanks, do you not see any configs attached, looks like I missed them off.
09-25-2008 04:27 AM
09-25-2008 04:27 AM
Here are the configs.
09-25-2008 08:24 AM
Hello Andy,
in order to get better help other info is needed :
on what port is connected the router
I suppose f0/1
on what ports are the PCs/routers
ip addr 192.168.3.x must be in vlan 20
post a sh int fas0/1 switchport so we can check if it is trunking, what protocol is using and what vlans are permitted
Hope to help
Giuseppe
09-25-2008 09:57 AM
Hi,
As my first post states:
I have a PC (PC A) with:
IP address - 192.168.2.50
Gateway - 192.168.2.1
In FE 0/9 of switch VLAN10
I have a PC (PC B) with:
IP address - 192.168.3.10
Gateway - 192.168.3.1
In FE 0/17 of switch VLAN20
And you are correct the router is in FE0/1
Output:
Switch#sh int fas0/1
FastEthernet0/1 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 000f.2477.0401 (bia 000f.2477.0401)
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, media type is 100BaseTX
input flow-control is unsupported output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:30, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 1000 bits/sec, 2 packets/sec
87 packets input, 11418 bytes, 0 no buffer
Received 30 broadcasts (21 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 21 multicast, 0 pause input
0 input packets with dribble condition detected
1658 packets output, 120475 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
Switch#
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