[c-nsp] 6500 SVI Question

[Pavel Skovajsa]

Hi Paul,

All virtual interfaces have "bandwidth" that has nothing to do with
real number of bytes per second that can flow through the link, For
example:

- all VSI interfaces have by default bandwidth of: "MTU 1500 bytes, BW
1000000 Kbit, DLY 10 usec,", even tough the real interfaces "behind"
are 10/half.... One way to explain this is that 10 years ago, in the
time of hybrid Catalysts, the switching part of Catalyst (SP) was
autonomous and consisted of real interfaces, and the routing MSFC part
(RP) consisted of only SVIs.

- all  tunnel interface have default "bandwidth" of 8000kb, which is
tricky way of saying to the routing protocol to not to prefer the
route over the tunnel and use it only as last resort

Also, all serial interface have default bandwidth of 1024kb, eventough
they might be fractional T1's or anything else.

-pavel skovajsa

On Tue, Feb 23, 2010 at 2:30 AM, Paul Stewart <paul at paulstewart.org> wrote:
> Thanks Tim.... whew! ;)
>
> Actually, I was misreading the bandwidth statement itself  - missed a zero
> earlier so thought you could only set it to 1 Gig, now I realized you can
> set it up to 10GE.  Updated it to 2Gig and everything good now..
>
> Much appreciated,
>
> Paul
>
>
> -----Original Message-----
> From: Tim Stevenson [mailto:tstevens at cisco.com]
> Sent: February-22-10 8:12 PM
> To: Paul Stewart; cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] 6500 SVI Question
>
> Hi Paul,
>
> The bandwidth does not affect the throughput etc and doesn't take
> into account the underlying L2 interfaces bandwidth. It strictly for
> use by the routing protocols to determine metrics (and can be
> modified using the "bandwidth" interface command). Also you can
> change the reference b/w using "ospf auto-cost reference-bandwidth"
> under the "router ospf" process.
>
> Hope that helps,
> Tim
>
>
> At 04:56 PM 2/22/2010, Paul Stewart mumbled:
>
>>Hi there...
>>
>>
>>
>>Typically when we require higher bandwidth, we upgrade the interface to
>>something larger ... recently though we were faced with having to do 2XGE
> on
>>a LAG until our new 10GE ports arrive.  The SVI interface shows a bandwidth
>>of 1 Gig even though there are two physical GigE interfaces "connected" to
>>it.... will there be any issues doing more than a Gig on this SVI
> interface?
>>This is the first time amazingly that I've run across this ;)
>>
>>
>>
>>The card where the two GigE's come into is a 6148A-GE-TX and the ports are
>>at opposite ends of the physical card...
>>
>>
>>
>>Thanks, appreciate it as always...
>>
>>
>>
>>Paul
>>
>>
>>
>>
>>
>>
>>
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>
>
> Tim Stevenson, tstevens at cisco.com
> Routing & Switching CCIE #5561
> Technical Marketing Engineer, Cisco Nexus 7000
> Cisco - http://www.cisco.com
> IP Phone: 408-526-6759
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