[c-nsp] Slow Inter-Vlan traffic

[Pete Lumbis]

Sounds like you have process switched traffic. You can watch the traffic
punted to the CPU with a NetDR capture "debug netdr capture...". This will
capture up to 1024 packets to memory. These are packets that are already
punted to the cpu so there is no additional impact from this command
(unlike other debugs).
https://supportforums.cisco.com/docs/DOC-15608

Can you show the interface configurations? My guess is there is something
that the hardware can't support like an ACL with a log keyword, or
misconfigured PBR.


On Wed, Apr 17, 2013 at 1:21 PM, Sébastien MALHEIRO <s.malher at gmail.com>wrote:

> HHi,
>
>
>
> We’re having some issues with inter-vlan traffic going pretty slow on
> 6504-E chassis working in VSS (VS-S720-10G / WS-X6748-GE-TX), running IOS
> version 12.2(33)SXH5.
>
>
>
> Here’s the thing :
>
> We have added 2 new Vlans on the swtichs (Vlan 41 : Production / Vlan 95 :
> Admin).
>
> Our customer told us that things are going pretty slow on both vlans (we
> have seen 1.5Mbits/s of maximum bandwidth on Vlan 41).
>
>
>
> Looking forward we saw that there is no distributed cache traffic on the
> SVIs :
>
>
>
> #sh interfaces Vlan41 stats
>
> Vlan41
>
>           Switching path    Pkts In   Chars In   Pkts Out  Chars Out
>
>                Processor      64954    4280562     155332    9976305
>
>              Route cache    6116040  589593156    8427463 10028760624
>
>        Distributed cache          0          0          0          0
>
>                    Total    6180994  593873718    8582795 10038736929
>
>
>
> #sh interfaces Vlan95 stats
>
> Vlan95
>
>           Switching path    Pkts In   Chars In   Pkts Out  Chars Out
>
>                Processor     732380   46887018    2009253  128644656
>
>              Route cache    8377033 4951406934    5756730  480387249
>
>        Distributed cache          0          0          0          0
>
>                    Total    9109413 4998293952    7765983  609031905
>
>
>
> On older (working well) SVIs added on the switchs we saw that packets are
> going to distributed cache.
>
> I’m not a expert on this but as far as I understand I can see that our
> linecards are working in acef mode and that cef is enabled on the 2 new
> SVIs (the sh cef interface output is the same on all the SVIs configured on
> the switchs) :
>
> #sh cef interface Vlan 41
>
> Vlan41 is up (if_number 460)
>
>   Corresponding hwidb fast_if_number 460
>
>   Corresponding hwidb firstsw->if_number 460
>
>   Internet address is X.X.X.X/X
>
>   ICMP redirects are always sent
>
>   IP unicast RPF check is disabled
>
>   Output features: HW Shortcut Installation
>
>   Inbound access list is not set
>
>   Outbound access list is not set
>
>   IP policy routing is disabled
>
>   BGP based policy accounting on input is disabled
>
>   BGP based policy accounting on output is disabled
>
>   Hardware idb is Vlan41
>
>   Fast switching type 22, interface type 147
>
>   IP CEF switching enabled
>
>   IP CEF switching turbo vector
>
>   IP Null turbo vector
>
>   IP prefix lookup IPv4 mtrie generic
>
>   Input fast flags 0x0, Output fast flags 0x0
>
>   ifindex 459(459)
>
>   Slot unknown (-1) Slot unit 41 VC -1
>
>   Transmit limit accumulator 0x0 (0x0)
>
>   IP MTU 1500
>
>
>
> #sh cef interface vlan 95
>
> Vlan95 is up (if_number 455)
>
>   Corresponding hwidb fast_if_number 455
>
>   Corresponding hwidb firstsw->if_number 455
>
>   Internet address is X.X.X.X/X
>
>   ICMP redirects are always sent
>
>   IP unicast RPF check is disabled
>
>   Output features: HW Shortcut Installation
>
>   Inbound access list is not set
>
>   Outbound access list is not set
>
>   IP policy routing is disabled
>
>   BGP based policy accounting on input is disabled
>
>   BGP based policy accounting on output is disabled
>
>   Hardware idb is Vlan95
>
>   Fast switching type 22, interface type 147
>
>   IP CEF switching enabled
>
>   IP CEF switching turbo vector
>
>   IP Null turbo vector
>
>   IP prefix lookup IPv4 mtrie generic
>
>   Input fast flags 0x0, Output fast flags 0x0
>
>   ifindex 454(454)
>
>   Slot unknown (-1) Slot unit 95 VC -1
>
>   Transmit limit accumulator 0x0 (0x0)
>
>   IP MTU 1500
>
>
>
> Moreover the “show ip cef vlan” output show that the good prefixes are
> attached to the SVIs.
>
> We also saw in the “show interface vlan” output that there are no “L3
> in/out Switched” packets going through.
>
>
>
> We would like to know where we could look to find the origin of this
> problem.
>
> Any Idea would be appreciated.
>
>
>
>  Thanks.
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