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Home > Archive > CCNP > April 2003 > InterVLAN Routing
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| dragon113 2003-04-18, 9:06 pm |
| Hi all!
I have Cisco 3600 Router and Catalyst 4000.I try to do InterVLAN routing but I have a problem that I can't do the ISL or 802.1Q trunking between 3600 & 4000 because I can't find "encapsulation" command in the "interface mode" of Cisco 3600 router.
I try another fast ethernet interface (fa 1/1)in Cisco 3600 router but the same result.
Do I need to do some step before? (I also enable Ip routing)
So Pls help me to solve this problem!!
Thank. | |
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| Hello dragon113
According to the Cisco CCNP Switching Guide here is what you need to do:
Create a sub-interface on your FastEthernet interface, then configure the encapsulation method, then assign an ip address. like this:-
Router(config)#interface fastethernet1/1.1
Router(config-subif)#encap isl 101
NOTE 101 is your VLAN number
Router(config-subif)#ip address a.b.c.d
Now that should work, HOWEVER, I tried it on a Cisco 3620 router running IOS version Version 11.1(20)AA2, and I am sorry to say that I could not configure the sub-interface nor the major interface with the 'encapsulation' command.
So, if it doesn't work for you, I don't know what to suggest, except that maybe the IOS needs to be at the right revision level, or perhaps the router hardware doesn't support this.
Anyone else want to add some comments?
Hippo
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| Hello again
I have configured inter VLAN routing on Catalyst 5500 and 6500 switches in the past, but they have integral routers. So, to do it with a external means I have something to learn as well. Therefore, I went to the Cisco web site and looked at an example configuration using a Cat 3512XL and a 2600 router. The config is attached below.
I am also checking whether the Cat 4000 switch you are using supoorts inter VLAN.
Cheers
Hippo | |
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| Oops!
The attach file didn't work first time. Trying again,,,, | |
| anchor40 2003-04-20, 9:52 pm |
| Interesting problem, I must say.
All Cisco switches (1900-8500) support Inter-VLAN routing, but use either the internal or external routing mechanism.
Hippo, your example and attachment are right on. You're trying to build the "router-on-a-stick" model, with potentially multiple VLANs over the trunk between the 3600 and Cat 4000.
I haven't config this for a 3600, but I'll check one of ours at work tomorrow to verify it was set up like below.
I don't think the encapsulation is available from the main interface (your first post hints that you were trying from fa0/0 and fa1/1), only via sub-interfaces.
Also be aware that the latest models are now defaulting to dot1q trunking, which is a change from the older models that defaulted to isl. Both sides must match speed, duplex, and encapulation type for the trunk to come up.
Once you verify the physical layer (link lights on both sides), the following should work for the 3600:
config)int fa0/0.1
config-sub-int)encap dot1q 101 <--or use isl
config-sub-int)ip add a.b.c.d
config-sub-int)exit
config)int fa0/0
config-int)no shut
config-int)end
Be sure both sides match speed, duplex, and encapsulation. After you config the router, show vlans and show interface fa0/0.1 to verify the functionality.
I'll post my 3600 findings tomorrow, but if you get it working, let us know! | |
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| ZacDogg 2003-04-21, 6:08 pm |
| Dragon and Hippo, i would guess that you don't have FastEthernet interfaces in your routers. You need at least FastE interfaces to do hairpin routing.
Zac | |
| dragon113 2003-04-21, 8:56 pm |
| ZacDogg, I'm sure that my cisco 3600 router has two fast ethernet interface (fa1/0, fa1/1).
Thank | |
| anchor40 2003-04-22, 12:09 am |
| I wasn't able to check our 3600 config - fighting an architecture layer 9 issue.
I'm going to try and work it in tomorrow.
P.S. In case you're wondering, in the "OSI" model layer 8 is "financial" and layer 9 is "Political" - two key points to remember in any design effort!  | |
| limsam 2003-04-23, 3:27 am |
| Ok, let me try this when I start to study for my swutching exam and let you know! |
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