[c-nsp] Whats happens when TCAM is full on 7600/RSP720RSP-3CXL?

["Rolf Hanßen"]

Hi,

at least for Sup720-3B(XL) and Sup-2T it results in number 1 for the
family that hit the limit.

So in most cases it will look that way:
#show mls cef exception status
Current IPv4 FIB exception state = TRUE
Current IPv6 FIB exception state = FALSE
Current MPLS FIB exception state = FALSE

And yes, the box will drop down to a few MBit of Traffic.

kind regards
Rolf

> Hi,
>
> I'm currently using a 7606 (RSP720RSP-3CXL) and taking in full BGP on v4
> and v6. Obviously it the TCAM is almost full and the box needs to be
> replaced.
>
> But a have a couple of questions.
>
> I have been hearing different scenario of what would happen when the
> TCAM is full:
> 1. The whole thing goes into software routing mode for all routes which
> causes 100% CPU and resulting and unusable box
> 2. New route entries will just get dropped, current entries just stay in
> TCAM
> 3. New route entries will be software routed, but entries that are
> already in TCAM will be hardware routed. You won't notice much impact in
> the beginning.
>
> What is true?
>
> The only reason that our 7606 needs to be replaces it because of the
> TCAM. It doesn't do much traffic, like 3Gbps upstream. Only BGP/OSPF.
> And not many ports, 8 x 10Gb fiber + 30 x 1Gb copper (local servers).
>
> We will probably go for the ASR9006. But I would like to use it like I'm
> using the 7600 now, as a router/switch. I have been reading that you
> need to make some uncommon config to create Ethernet VLAN/Trunk
> interfaces and ports, as this is not commonly not done with this router.
> But is this good practice? Will it be fine once I fingered it out?
>
> Last question. Can I take a full BGP feed on both v4 and v6 with a
> A9K-RSP440-TR? Or do I need the -SE?
>
> Chiel
>
>
>
> Bellow are some output of our current 7600:
>
> #show mls cef maximum-route
>  Â IPv4 + MPLSÂ Â Â Â Â Â Â Â  - 832k (default)
>  Â IPv6Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  - 90k
>   IP Multicast        - 1k
>
> #show mls cef su
> Total routes:Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  915422
>  Â Â Â  IPv4 unicast routes:Â Â Â Â Â Â Â Â Â  822144
>  Â Â Â  IPv4 Multicast routes:Â Â Â Â Â Â Â  8
>  Â Â Â  MPLS routes:Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  2050
>  Â Â Â  IPv6 unicast routes:Â Â Â Â Â Â Â Â Â  91220
>  Â Â Â  IPv6 multicast routes:Â Â Â Â Â Â Â  3
>  Â Â Â  EoM routes:Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  0
>
> #show mls cef exception status
> Current IPv4 FIB exception state = FALSE
> Current IPv6 FIB exception state = FALSE
> Current MPLS FIB exception state = FALSE
>
> #show platform hardware capacity forwarding
> L3 Forwarding Resources
>   Module              FIB TCAM usage: Total       
> Used     %Used
>  Â Â  2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  72 bits (IPv4, MPLS,
> EoM)Â Â Â Â Â  851968
> 824115Â Â Â Â  97%
>  Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  144 bits (IP mcast,
> IPv6)Â Â Â Â Â Â  98304 91198Â Â Â Â  93%
>
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