Re: [nsp] Frame-relay CIR

From: Alexandros Sichlimiris (alexandross@yahoo.com)
Date: Wed Oct 10 2001 - 05:25:51 EDT


I think that you will also find this useful:
http://www.cisco.com/warp/customer/125/21.shtml

Alex
--- Stephen Sprunk <ssprunk@cisco.com> wrote:
> Thus spake <francisv@dagupan.com>
> > Our telco provided us with a frame-relay link with
> a guaranteed
> bandwidth
> > of 128K that can burst up to 256K -- how does
> information fit in my
> > frame-relay map-class? (see my comments within the
> map-class)
> >
> > map-class frame-relay mynet-to-hq
> > no frame-relay adaptive-shaping
>
> If you're going to configure for bursting, you
> should enable
> "frame-relay adaptive-shaping becn"; otherwise you
> won't respond to BECN
> flags and will end up dropping lots of traffic.
>
> > frame-relay cir 256000
> > ! Should the CIR value be set to 128000? If this
> is set to 128K,
> > ! will the link still burst to 256K?
>
> In the US, this should be the PIR (eg. 256k).
> Outside the US, this
> should be the contracted CIR (eg. 128k).
>
> The reason for this is non-US carriers rarely allow
> actual bursting;
> you're lucky if you get full CIR. In the US, you
> can usually get PIR
> 24x7 without problems.
>
> > frame-relay bc 2560
> > ! How about the committed burst value? I'm also
> running VoIP
> > ! on this link
>
> cir/100 gives you Tc=10ms, which is fine for VoIP
> networks.
>
> > frame-relay be 0
>
> I'd recommend Be=Bc*7.
>
> > frame-relay mincir 128000
> > ! Is this necessary?
>
> It's not necessary since default is mincir=cir/2,but
> I prefer to set it
> explicitly rather than rely on defaults.
>
> > frame-relay fair-queue
> > frame-relay fragment 320
> > ! Where should I base my fragment value?
>
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft
> /120limit/120xg/120xg3/12xgvofr/vofr4.htm#41606
>
> The formula is F=P/800, where F is the fragment size
> in bytes, and P is
> the PIR (aka "frame-relay cir") in bps.
>
> > frame-relay ip rtp priority 16384 16383 45
>
> If you're running 12.1(3)T or later, I'd recommend
> using LLQ instead of
> RTP Priority (now deprecated) and matching on
> precedence 5 traffic.
>
> S
>

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