Re: [nsp] [nsp] RSP8 amd Rec. Side Buffering (was: VIP if-con and IOS switching)

From: Siva Valliappan (svalliap@cisco.com)
Date: Wed May 30 2001 - 02:05:08 EDT


if i remember correctly, we can't do local DSW (within PAs in a VIP) if you
are using POS PAs. afaik there is no difference with VIP4s, but i would
need to check.

cheers
.siva

>
> On Wed, May 30, 2001 at 12:05:13AM -0400, Martin, Christian wrote:
> > I am doing performance testing on a 7513 using VIP2-50s with PA-POS-OC3
> > cards (8 all together). dCEF enabled, with 65000 flows running through it
> > for a total of 600Mbps aggregate (70kpps with .1% loss). The CPU on the RSP
> > is fine (0%). The VIPs are all at 99% doing RSB. The problem is this:
> >
> > 1) There isn't enough MEMD on RSP4 to switch packets agressively between
> > VIPs, and
> > 2) There isn't enough CyBUS bandwidth to do so either.
> >
> > What I am about to do is load up some RSP8s and rerun my test, as the 64MB
> > of MEMD should help with the RSB drop issue. My question is this:
>
> 8MB of MEMD on RSP8, not 64MB. But it's still a lot more than 2MB.
>
> >
> > Does RSP8 add 'bandwidth' to the CyBUS or do we need VIP4-80s to get 4Gbps
> > (I seem to remember something about a CzBUS)? I want to see how far the
> > 7513 can go.
> >
>
> You need the VIP4s (50 or 80) to get more bandwidth.
>
> > Anyway, the important point to remember is that true distributed switching
> > on the RSP platforms only occurs between PA's in the same VIP (unlike the
> > GSR). InterVIP switching requires the RSP to manage access to MEMD between
> > VIPs (hence the high amount of RSB drops when the load is high).
> >
>
> Intra-vip switching isn't always purely local to the VIP. There are
> some timing and starvation issues where with some PAs, we still send
> traffic to MEMD. It's not often, and it only shows up in the
> high-speed PAs, and I'm not sure if VIP4s alleviate that at all, but
> that's how a few PAs on VIP2s behave.
>
>
>
> eric
>



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