[c-nsp] Cisco trunk port startup delay

[Joshua Morgan]

carrier-delay?

Sent from my iPhone

> On 17/07/2013, at 11:23, Shanawaz Batcha <ismath.shaan at gmail.com> wrote:
> 
> Thanks for the suggestions.
> 
> * I am definitely not disabling spanning-tree. I have enabled 'portfast
> trunk' on the port which reduced the port uptime significantly.
> * Disabling a lot of negotiation protocols improves port initialization
> time as well
> 
> However we still lose about 5 pings. Digging further, I find that it takes
> about 4 seconds for the 6500 to register a port-transition. Down to up or
> up to down. So from the moment, a cable is plugged in, it takes about 4
> seconds for the SP to register the port as up and pass traffic. This is
> just layer 1, not spanning-tree or anything.
> 
> Is this as good as it gets or is there a trick to perhaps get this time
> further down?
> 
> 
>> On Sat, Jul 13, 2013 at 9:19 AM, james <james at mutexit.com> wrote:
>> 
>> He is utilizing bpduguard as well so that should help reduce the chance of
>> a loop.
>> 
>> 
>> Sent from my Verizon Wireless 4G LTE Smartphone
>> 
>> 
>> 
>> -------- Original message --------
>> From: Tóth András <diosbejgli at gmail.com>
>> Date: 07/12/2013 6:00 PM (GMT-05:00)
>> To: Tom Storey <tom at snnap.net>
>> Cc: Shanawaz Batcha <ismath.shaan at gmail.com>,cisco-nsp at puck.nether.net
>> Subject: Re: [c-nsp] Cisco trunk port startup delay
>> 
>> 
>> I would not encourage disabling STP at all, "portfast trunk" already
>> increases the chances of creating a loop, on the other hand it does allow
>> the port to transition to STP forwarding state immediately, so it should
>> have the same effect.
>> 
>> Given that the delay is due to the actual link down and likely re-ARP-ing,
>> the only option for further reduce the delay is to dual-home the servers,
>> preferably with a port-channel (etherchannel) such as 802.3ad LACP. That
>> will provide redundancy and sub-second failover if one member link goes
>> down or flaps.
>> 
>> Andras
>> 
>> 
>> 
>>> On Fri, Jul 12, 2013 at 7:26 PM, Tom Storey <tom at snnap.net> wrote:
>>> 
>>> If they are connecting to servers, do you really need spanning tree?
>>> 
>>> I assume that spanning tree is blocking for x period of time, where x is
>>> long or short depending on whether portfast is enabled.
>>> 
>>> If you remove spanning tree then there is no blocking, and it should come
>>> up and be able to pass traffic as quickly as MAC tables can update?
>>> 
>>> 
>>> 
>>>> On 11 July 2013 01:32, Shanawaz Batcha <ismath.shaan at gmail.com> wrote:
>>>> 
>>>> Hi Guys,
>>>> 
>>>> Question for you is how soon can we get a cisco trunk port (connecting
>> to
>>>> some enterprise servers) to initialize and pass traffic.
>>>> 
>>>> From
>>>> 
>>>> interface GigabitEthernet4/40
>>>> 
>>>> switchport
>>>> 
>>>> switchport trunk encapsulation dot1q
>>>> 
>>>> switchport trunk native vlan 104
>>>> 
>>>> switchport mode trunk
>>>> 
>>>> spanning-tree bpduguard enable
>>>> 
>>>> end
>>>> 
>>>> 
>>>> With the above configuration, we were losing about 50 pings for an
>>> if-down
>>>> event
>>>> 
>>>> Enabling "portfast trunk" (no redundant connections), we lost somewhere
>>>> between 10 and 15 pings. Which is way better.
>>>> 
>>>> Running "switchport nonegotiate" to disable DTP gives me another ~2
>>> seconds
>>>> 
>>>> Disabling inline power and "disabling lldp" gives me another ~1 or 2
>>>> seconds
>>>> 
>>>> We are still losing about 6 pings. Anything else people do/tune to get
>>>> quicker convergence if I may call it?
>>>> 
>>>> Regards,
>>>> Shan
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> 
> 
> 
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