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New Member

Splitting an Internet Link on a guaranteed basis

Hi folks.

I'm new to cisco and need your input on a topic. My own research has identified lots of different gadgets out on the market that can do what I want, but I hae heard it is easily possible with a decent Cisco switch.

We have an 10MB Internet connection coming in through a leased line and terminated by the ISP using a Cisco router. As it is managed, all they provide is a single CAT5 connection and have given us a good sized range of public IPs.

We want to effectively split this 10Mb link into two (one with 4Mb, the other with 6Mb). The idea being that the individual splits only get what they are programmed for and NOTHING extra. The background is the 4Mb one is going to be used by 40 people for typical web browsing/internet usage and the 6Mb link is going to be used by a new Video Conferencing system.

The 4Mb link will plug into our existing Sonicwall Firewall which then links to our client PCs spread accross Cisco and HP Switches on 100Mb with Gig uplinks.

THe other link will need to accomodate a VC unit which will have a public IP for external Video conferencing.

I've seen kit from Packeteer, DBAMsystems who all offer WAN splitting, but I noticed at another site an ISP has their main feed coming in on a 2650 and two cat5 connections then fed two separate company networks so I assumed the ISP must throttle the links to these two separate clients.

I'd love to hear your thoughts on how to provide this simply.

internet connection

New Member

Re: Splitting an Internet Link on a guaranteed basis

You can use QOS.

Something similar to this:

class-map match-any VIDEO

match protocol h323

class-map match-any WebEmail

match protocol http

policy-map Policy

class VIDEO

  priority percent 60

 class WebEmail

  bandwidth remaining percent 40

class class-default


interface FastEthernet1

bandwidith 10000

 ip nbar protocol-discovery

 service-policy output Policy

New Member

Re: Splitting an Internet Link on a guaranteed basis

Hey, thats great thanks for the posting.

I have some more questions. (sorry).

1. Looking at what you have putogether above, it looks as though it is configured specifically for video/h323 and http. If things like ftp, smtp etc are needed would the config need to keep changing.

2. which entry/mid level switch would you suggest. I am being advised the ISP will provide some sort of Cisco router with a single CAT5 connection that will go into say port 1 of this new switch. Then ports 2 will go off to firewall 1 (normal office LAN) and port 3 will go off to firewall2 (VC LAN).

Each firewall will then open/close/forward ports as needed according to the application in question.?

Will I not need VLANs on this switch ?.

Is there a specific IOS I need for this?.

Last question- It sounds so simple. Is it really that simple.

Super Bronze

Re: Splitting an Internet Link on a guaranteed basis

Do you want this bandwidth split for output, input or both? (NB: Input will likely not provide the results you desire.)

Are you sure you want to limit bandwidth such that nothing extra is used even if the other bandwidth is available?

For equipment selection, any chance that you might want to support more than 10 Mbps?

BTW: Devices such as Packeteer's offers features that aren't available on switches and routers.


BTW: Peter's example would need the FastEthernet running at 10 Mbps to be effective. It also may not limit video to 6 Mbps nor does it limit other traffic to 4 Mbps. (Also unclear why there's both a WebEmail class and class-default and why the former is using bandwidth remaining percent 40. Also unclear why NBAR protocol discovery active.)

Re: Splitting an Internet Link on a guaranteed basis


Since the Wan connection is leasedline, then you cant spilit it and I am wondering How they could afford 10Mbps link.

Anyways, What you can do, is Logically seperate your lan Links into 2 Vlans since the Lan is Ethernet Media. assuming your Firwall is connected behind the GW router. So , basically , One logical subinterface used as Firwall Gw, and the second used by your Webbrowsing users. On the LAN you could then implement Policing Or Shaping using MQC or GTS or CAR standards.

Packeteer wouldnt help here, its mainely designed to classify traffic and prioritize them at application layer besides shaping. Its generally used by ISPs. If you need to prioterize your local traffic then you could classify your traffic based on NBAR (BNetwork Based Application recognition) and apply your desired action.