[c-nsp] SIP-400 oversubscription

[Tony]

Hi all,

I have a SIP-400 in a 7609 (running 12.2(33)SRD1 if it matters). The SPA's that are currently installed are one 2-port Gig & one 4-port OC3 (SPA-2X1GE & SPA-4XOC3-ATM). I would like to add a 5-port GigE (SPA-5X1GE-V2) into the same SIP-400. I've been reading through the Cisco doc and find references like this:

===

As of Cisco IOS Release 
12.2(18)SXF, when using the Cisco 7600 SIP-400 with the 2-Port Gigabit 
Ethernet SPA or the 1-Port OC-48c/STM-16 ATM SPA, consider the following oversubscription guidelines:  
–The Cisco 7600 SIP-400 supports installation of up to two 2-Port Gigabit 
Ethernet SPAs without any other SPAs installed in the SIP. –The Cisco 7600 SIP-400 supports installation of any combination of OC-3 or 
OC-12 POS or ATM SPAs up to a combined ingress bandwidth of OC-24 rates, when installed with a single 2-Port Gigabit Ethernet SPA.

===

Which says I can have "1x OC3 + 1x 2-port GigE" (my current setup)  OR  "2x 2-port GigE". The above makes no mention whatsoever about the 5-port GigE card, either by itself or with OCx cards.

I realise that the above is due to the bandwidth of the SIP-400 being 4Gbps (I think ?) and so Cisco want you to keep it below this figure to avoid over-subscribing the bandwidth of the device.

We currently have about <50Mbps of traffic on the OC3 card and <200Mbps on the 2-port GigE card.

My question is if I add a 5-port GigE card to my setup (in addition to 2-port GigE & 4-port OC3) what will happen ? Will everything work and it just log a message about "bandwidth points exceeded - unsupported" (which I will hapily ignore) ? Will it not power on the extra 5-port card ? Will it shutdown tne entire SIP ? Will my 7609 spantaneously combust leaving me with just a pile of ashes ? (ok, that's probably unlikely)

Is the bandwidth oversubscription just a cosmetic type thing or is it enforced in some way ? Is anyone running lots of 2 or 5 port GigE cards and not having any issues with them ? Would I even be able to remove my 2-port cards and add 2x 5-port cards to give me 10x GigE ports on the SIP ? I am not too worried about bandwidth through the interfaces, it's unlikely we will be pushing more than an aggregate of 1Gbps over all the GigE ports, even if we add more. I'm just looking at increasing the number of GigE "WAN" ports available without having to replace SIP with ES (we would still need the SIP for OC3/ATM anyway).



Thanks,
Tony Miles.