General discussion


Vlans and routers

By souter94 ·
I was told that all routers and switches can interface with vlans. I am trying to create a subinf and then run the encap command on a router.
The router has the encap command in the ios but will not except it - saying the command is not recognized. Could it be the ios that is restricting me or are ther some routers that are not configurable?

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by InXale In reply to Vlans and routers


Whats the hardware you are using?


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by souter94 In reply to Vlans and routers

There are 1720 routers going to 7200 routers. 3500 series switches behind these routers.

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by souter94 In reply to Vlans and routers

I am working with a 1720 and 7000 series router.
I am worried that the 1720 does not support vlans.

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by CG IT In reply to Vlans and routers

ah, the 3600 ought to be able to VLAN which you then uplink to your 1720 access routers on one of the e0 or e1 depending upon its hardware config. If I remember right the 1720 can be configured for a T1 or ADSL or whatever with modules for WAN but only has 1 e0 for LAN side.

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by dplewis In reply to Vlans and routers

Support for VLANs on Cisco switches and routers is both hardware and software dependent. In particular the routers may need the right feature set (E.g. IP Plus) and/or the right IOS version. These things will also influence DRAM and Flash memory requirements. Find the Feature Navigator (login required) on to work out what IOS you need. Note also, in Cisco world that you need to standardise on a LAN trunking (tagging) method. Older switches may only support Cisco-proprietary InterSwitch Link (ISL) - I recommend using the open-standard 802.1Q. Remember; if you're routing between VLANs you're usually much better doing it on a Layer-3 switch (Cat 3550, 3750 or suitable 4000 or 6000 chassis) as they'll be on or near wire-speed. Many routers (especially older ones) struggle to achieve this.

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by Greybeard770 In reply to Vlans and routers

Never say ALL.
Many switches support VLANs but do not provide for routing between VLANs. The Nortal 350 and 450 are examples or that. Routing between VLANs requires a more sophisticated Layer 3 (routing) switch like the Passport series. The Cisco world has similar options. Dig deeper into the documentation of your hardware. Good luck.

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by thomas_nooning In reply to Vlans and routers

I don't believe the 1720s support VLANs, the 1721 does though. Not an IOS issue but a hardware one. What are the 1720's doing that you can't plug straight into the 7200? And what version of 3500 series switch are you using? If it's a layer 3 like a 3550 or 3560, you can do everything you need to do on the switch itself.

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