09-06-2004 02:08 AM - edited 03-02-2019 06:16 PM
I am having an issue with VLAN trunking between a C2950 and a 1721 router,
If I create a trunk on an etherner port on a 2950, will the 1721 support trunking on its 10/100 interface.
I have configured a trunk on 2950 using
"switchport trunk allowed vlan 102,104"
On the 1721, will creating dot1q subinterfaces for each vlan work.
I have done this- both boxes can see each other by CDP, but we cannot ping.
Apologies for such a simple question, but I have never used 1700's before ( used to 2600 and above)
Thanks in advance.
09-06-2004 02:53 AM
Hi,
what is your native vlan. You should try to configure your native vlan also. When it doesn#t works please post you configs, thanks.
Regards
Peter
09-06-2004 05:15 AM
Peter,
Thanks for the reply.
On the 1721 , I have configured the following
interface FastEthernet0
no ip address
speed 100
!
interface FastEthernet0.102
description =Voice vlan=
encapsulation dot1Q 102
ip address x.x.x.x 255.255.255.0
!
interface FastEthernet0.104
description =Data Vlan==
encapsulation dot1Q 104
ip address x.x.x.x 255.255.255.0
On the 2950, I have configured
interface fast 0/1
switchport mode access
switchport trunk allowed vlan 102,104
speed 100
I will try adding the "switchport trunk native vlan x" when I go back to customer site tomorrow.
Many thanks
09-06-2004 05:30 AM
You should also change your 1721 subinterface config to
encapsulation dot1Q x native
where x means either 102 or 104 depending on VLAN chosen as the native one on your trunk.
And there must be
switchport mode trunk
on your switch port.
Regards,
Milan
09-06-2004 05:33 AM
Thanks Milan
09-06-2004 04:00 AM
You will probably also need the command"
"switchport mode trunk"
under the 2950 switchport interface.
Have a look at:
Bill.
09-06-2004 05:31 AM
Bill,
Thanks for the respose.
I'm normally ok with trunking, but I'am a little confused with the 1721 side of things.
The only documentation I can find on 1721 and trunking is using the subinterfaces - but I'm not sure that this is the right way of doing things.
Is this possible on a 1721 with a single 100Mb interface, or is it advisable to use a 26xxXM or add another etherner interface,
Many thanks
Elliot
09-06-2004 05:50 AM
Read this for detailed understanding:
http://www.cisco.com/warp/customer/473/50.shtml#Tools
Regards,
Milan
09-06-2004 06:08 AM
Thanks Milan.
10-07-2004 01:47 AM
I am also trying to do the same thing on a Cisco 1721. However I am unable to execute the command:-
int fa0.1
encapsulation dot1q 1 native.
^
It does not like dot1q ( or isl )
I have only tried IP Plus software (12.2.15T) and the new 12.3 .11.T IP software but I get the same problem.
IOS stuff says that these support Vlans. However could it be that I need a different feature set. Only have 48M memory so cant try anything greater
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