Router on a Stick on 1721 router

Hi all, I want to implement VLAN in our company but I don't have a Layer 3 switch. We have 5 Catalysts 2960 which is now working as a flat network. We have an old Cisco 1721 router with 1 FastEthernet and 1 Ethernet interface.Can I implement VLAN and configure my subinterface on the router? What is the drawback of implementing VLAN with an old router?

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Comments

bighornsheep

I'm assuming your 2960s are uplinked on a common VLAN; how does this VLAN connect to the Internet? I'm assuming you have a Gateway router of some sort? What's your Internet BW?

The 1721 is a great gateway router for a small office, router-on-a-stick is a very trivial feature and you should have no problem running this configuration with a small topology. Just don't go crazy with the VLANs. With the right IOS, you can even run it as a VPN gateway for remote access, and IOS Firewall!

ColbyG

1721s are very old and very slow.

chmorin

ColbyG wrote: »

1721s are very old and very slow.

Agreed. I'm throwing a number out of my rear here but I'd say if you have anything over 20-40 or so users active on your network you might see some drawbacks.

Otherwise, you should be able to implement ROAS in this situation.

earweed

On a side note: every time I see the term "router on a stick" I think of Jose Jalapeno

tech-airman

jojopramos wrote: »

Hi all, I want to implement VLAN in our company but I don't have a Layer 3 switch. We have 5 Catalysts 2960 which is now working as a flat network. We have an old Cisco 1721 router with 1 FastEthernet and 1 Ethernet interface.Can I implement VLAN and configure my subinterface on the router? What is the drawback of implementing VLAN with an old router?

jojopramos,

What would the purpose of the router be for your company network?

Bl8ckr0uter

earweed wrote: »

On a side note: every time I see the term "router on a stick" I think of Jose Jalapeno

LOL you are not the only one.

ColbyG

phoeneous wrote: »

Throw a gigabit interface on it and you'll be in a better spot.

I don't think you could get a gig interface on there, but even if you could, it doesn't help anything. You're limited by the power of the router, not the speed of the interfaces.

Mark Knutson

My 1721 can pass about 9 meg, so its hard to imagine a production environment that would find that fast enough.

jojopramos

Hi all. We have an Astaro firewall (4 Mbps DSL - external) (4 Cisco Catalyst, HP Procurve switch 2010 PoE - internal) connection. Sorry that we don't have that big budget to incorporate an all Cisco device as Cisco ASA firewall and PoE switches are more expensive. We are also using AVAYA IP Phone, that is why we need the HP Procurve for PoE. Then our PC's are connected via IP Phone ethernet slot. We also have 50 users in our company and for this I want to implement VLANs on our servers, sales, finance and the last vlan is the remaining users to segregate broadcast domain. I reviewed the HP Procurve and access and voice are segregated already in the VLAN (voice vlan). The guys who implemented voice vlan are avaya guys. Now, I am planning to create our own VLAN to improve the performance of our network. By the way, how many users you should have in a company before implementing VLAN? As for now, I want to improve our network infrastructure and change from being a flat network using class c /24 classfull network. Please advise. I also read from Todd Lamle's 6th ed that 1721 is not capable of 802.1q trunk implementation.

jojopramos

tech-airman wrote: »

jojopramos,

What would the purpose of the router be for your company network?

To configure the subinterface for the VLAN dude. I downt have a layers 3 switch to create switch virtual interface (SVI).

mikej412

jojopramos wrote: »

I also read from Todd Lamle's 6th ed that 1721 is not capable of 802.1q trunk implementation.

Where did it say that? A 1721 with the proper feature set (and version number after the feature was added) can do 802.1q trunking.

A 1720, on the other hand, is a router with 100Mb Ethernet Interface that can't (according to the Cisco Docs).

jojopramos

Hi Mike, correct me if im wrong but based on CCNA 6th ed. by Todd Lamle, page 567 (routing bet VLANs) it says " The 1600, 1700 and 2500 series don't support ISL or 802.1q routing. Id recommend at least a 2800 as a bare minimum". I will check on my 1721, as I think, you are right that with a proper feature set, it will do the 802.1q. Anyway, I can do interVLAN routing on 1721, that would be great. For the meantime, I will first check the IOS version and feature set of my 1721.

Bl8ckr0uter

jojopramos wrote: »

Hi Mike, correct me if im wrong but based on CCNA 6th ed. by Todd Lamle, page 567 (routing bet VLANs) it says " The 1600, 1700 and 2500 series don't support ISL or 802.1q routing. Id recommend at least a 2800 as a bare minimum". I will check on my 1721, as I think, you are right that with a proper feature set, it will do the 802.1q. Anyway, I can do interVLAN routing on 1721, that would be great. For the meantime, I will first check the IOS version and feature set of my 1721.

I can verify that with Advanced Enterprises I was able to do 802.1q trunking on my 1721s.

ColbyG

mikej412 wrote: »

Where did it say that? A 1721 with the proper feature set (and version number after the feature was added) can do 802.1q trunking.

A 1720, on the other hand, is a router with 100Mb Ethernet Interface that can't (according to the Cisco Docs).

I've gotten ROAS working with a 1721, but wasn't able to with a 1720. It was quite awhile ago, so could have been IOS/memory related, but I don't think you can pull it off on the 1720s.

tiersten

ColbyG wrote: »

I've gotten ROAS working with a 1721, but wasn't able to with a 1720. It was quite awhile ago, so could have been IOS/memory related, but I don't think you can pull it off on the 1720s.

Yeah. 1720s were limited in memory/flash and had a corresponding limitation in IOS feature support. I think the best you can get is IP base + ADSL which won't do 802.1q. If you're going to buy a 1700 then don't buy the cheap 1720s!

tiersten

jojopramos wrote: »

Todd Lamle, page 567 (routing bet VLANs) it says " The 1600, 1700 and 2500 series don't support ISL or 802.1q routing. Id recommend at least a 2800 as a bare minimum".

I hope that is a typo on the 2800...

tiersten

Mark Knutson wrote: »

My 1721 can pass about 9 meg, so its hard to imagine a production environment that would find that fast enough.

Thats prolly 9Mbps with nothing enabled as well. Add some ACLs and other features and the throughput will drop like a stone.

mikej412

jojopramos wrote: »

correct me if im wrong

Nope -- you're right. And it's not in the errata.

You found it -- you have to report it.

There are 1700 series routers that trunk.

ColbyG

tiersten wrote: »

I hope that is a typo on the 2800...

Yea, no kidding.

jojopramos

mikej412 wrote: »

Nope -- you're right. And it's not in the errata.

You found it -- you have to report it. There are 1700 series routers that trunk.

Thanks Mike. Now that I know I can configure my 1721 to be a ROAS.