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RE: Connecting two core switches / Design posted 06/01/2004
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We use 2 6509's that are layer two connected for our access layer and 2 6509's for our core that are layer 3 connected. We connect the access layer switches to the core switches with one layer 3 connection to each (full mesh). We just converted the layer 2 trunk between the core switches to layer 3 and removed all hosts from the core switches. We also just finished changing all the fiber connections between the 4 6509's (2 core and 2 access) from Gig to 10Gig....works nice!

-----Original Message-----
From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx]On Behalf Of
Kenneth Wygand
Sent: Tuesday, June 01, 2004 4:59 PM
To: P729; Group Study
Subject: RE: Connecting two core switches / Design


Mas,

This brings me back to the real source of my question - then what would
be the best way to interconnect, say, two 6509 switches in my core?

Kenneth E. Wygand 
Systems Engineer, Project Services
CISSP #37102, CCNP, CCDP, ACSP, Cisco IPT Design Specialist, MCP, CNA,
Network+, A+
Custom Computer Specialists, Inc. 
"The only unattainable goal is the one not attempted."
-Anonymous

-----Original Message-----
From: P729 [mailto:p729@xxxxxxx] 
Sent: Tuesday, June 01, 2004 4:27 PM
To: Kenneth Wygand; Group Study
Subject: Re: Connecting two core switches / Design

I'd recommend keeping the core as fast and streamlined as
possible--perhaps
minimal ACL's to guard against potential errors in ACL's made in the
distribution layer(s) not under your administrative control. I wouldn't
go
so far as to say keep QoS out of the core completely: I'd push
classification and policy enforcement out as far to the edge as
possible/practical--at least to the distribution layer and use QoS only
for
queue management in the core (set the trust boundary at the distribution
layer to protect the core and keep it fast). Oversubscription? If you
have a
robust and diverse core, you may want to consider expected service
levels
during potential outages and perhaps keep critical links
_under_subscribed
by a certain amount.

Regards,

Mas Kato
https://ecardfile.com/id/mkato

----- Original Message ----- 
From: "Kenneth Wygand" <KWygand@xxxxxxxxxxxxxxxx>
To: "Group Study" <ccielab@xxxxxxxxxxxxxx>
Sent: Tuesday, June 01, 2004 8:47 AM
Subject: Connecting two core switches / Design


> Hello all,
>
>
>
> I was thinking about large providers that need to connect core
switches
> at very fast speeds. For example, say I have two 6506 core switches I
> wanted to connect in the backbone.  Say each one is terminating 20 -
30
> fiber gigabit speed links.  I would think it would be a poor idea to
> oversubscribe the link between these switches to a 1GBit or even
10GBit
> link.  If the link was oversubscribed, logic would think that QoS
should
> be employed here to make sure critical traffic (voice, video) gets
> through first, but all design guides point towards keeping all QoS out
> of the core to simply switch packets as fast as possible...
>
>
> What is recommended and is there any documentation / experience anyone
> can contribute?
>
>
>
> Thanks!
>
>
>
> Kenneth E. Wygand
> Systems Engineer, Project Services
>
> CISSP #37102, CCNP, CCDP, ACSP, Cisco IPT Design Specialist, MCP, CNA,
> Network+, A+
> Custom Computer Specialists, Inc.
>
> "I am not really smart. I just stick with problems longer."
> -Albert Einstein
>
>
>
> Custom Computer Specialists, Inc.
>
> "Celebrating 25 Years of Excellence"
>
> [GroupStudy removed an attachment of type image/gif which had a name
of
image001.gif]
>
>
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