RE: [spam score 3/10 -pobox] RE: Router with bandwidth management

["Mark Tinka" <mtinka at africaonline.co.ug>]

Well Brian, that then brings us back to Cisco's basic bandwidth management
implementation, CAR [rate-limiting].

By defining contract bandwidth, you set the actual bandwidth your client is
paying you for, in your example, 256Kbps out of 512Kbps. However, you can
give the client some lee-way by adding minimum and maximum burst capacities,
if you profile such a business model in your setup. This is *kind* of the
same way it is done on frame relay switches, except this is for Ethernet.

You're right about the queueing, it's easier and better to create a flow for
a general case of users, and not for particular users. This way, it works
best. However, for CAR, you can rate-limit an individual client by IP
address, traffic type, Layer 4 port, e.t.c, using a single Ethernet
interface or multiple Ethernet sub-interfaces. Of course, to use Ethernet
sub-interfaces, you will need a VLAN trunking protocol.

I believe with a Cisco router, if Robert doesn't intend to
purchase/configure extra hardware, it can serve as his entry level bandwidth
management solution. The overhead is not as heavy as it sounds. He will
still get very good performance on his routers.

Regards,

Mark Tinka - CCNA
Network Engineer
Africa Online Uganda
5th Floor, Commercial Plaza
7 Kampala Rd,
Tel:   +256-41-258143
Fax:   +256-41-258144
E-mail: mtinka at africaonline.co.ug
Web:     www.africaonline.co.ug
 

-----Original Message-----
From: Brian Candler [mailto:B.Candler at pobox.com] 
Sent: Sunday, May 18, 2003 7:49 PM
To: Mark Tinka
Cc: 'Robert'; afnog at afnog.org
Subject: Re: [spam score 3/10 -pobox] RE: Router with bandwidth management


On Sun, May 18, 2003 at 03:00:37PM +0300, Mark Tinka wrote:
> Brian, you can do full queueing, prioritisation and compression on 
> Cisco routers.

I don't think it's possible to do traffic shaping on an ethernet or dialer
interface of a Cisco router, in the way I described (i.e. out-of-profile
traffic is queued/delayed, not dropped) but if I'm wrong I'd certainly like
to see how to do it.

I wouldn't want it because of insufficient bandwidth or congestion, it's for
product differentiation. For example, given a 512K physical layer (DSL), you
may wish to sell a 256K service to the customer.

As another example, in London it's very cheap to buy a 100Mbps LAN-extension
service over fibre from the local telcos - in many cases similar cost to a
2M SDH circuit. But the customer probably doesn't want to buy 100Mbps of
transit - they may only want 5Mbps, or 20Mbps, or whatever. So you want to
be able to control their flow rate on an ethernet interface, to give a
simulated 5Mbps leased line (say).

I think that's pretty similar to the wireless problem discussed here - given
a link layer which might run at up to 11Mbps, you want to be able to
restrict the Internet usage of individual customers to say 64Kbps or
whatever they have contracted to buy.

> The 4 main culprits are:
> 
> 1. FIFO - First In First Out
> 2. WFQ - Weighted Fair Queueing
> 3. Priority Queueing
> 4. Custom Queueing

But do any of those let you control the *amount* of bandwidth assigned to a
particular user or flow, in absolute terms (i.e. X Mbps per second)? I
thought they were all just relative (i.e. flow X packets take priority over
flow Y)

Regards,

Brian.




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