Cat 6500 with Dual Sup720 design

[bdyzel123]

Hi,

I've been reading up on a lot of material and so far only managed to confuse myself further.

We currently run a;

two chassis, single sup720 to each chassis, with two 48 port CFC G modules per chassis, and an ACE module per chassis.

I've been requested to add an additional sup720 mainly in order to make use of the additional two onboard uplink ports for SFP.

The reasoning for this is that the current sup720 per chassis runs one port to distribution switch1, and the second port to distribution switch 2 via SFP Fibre. When the second sup720 is added we would like to etherchannel the 1st sup720 to distribution switch 1, and the second sup720 to distribution switch 2. (there is no chance for us to use copper connections via the CFC's to connect to the distribution switches)

I've noted some concerns;

"The standby supervisor engine is isolated from the system bus and does not switch packets. But it does receive packets from the switching bus to learn and populate its Layer 2 forwarding table for

Layer 2-switched flows. The standby supervisor engine also receives packets from the switching bus to learn and populate the Multilayer Switching (MLS) table for Layer 3-switched flows. The standby supervisor engine does not participate in forwarding any packets and does not communicate with any modules."

My question is;

1) Will the second sup720's two onboard uplink ports still function normally, and pass traffic to both the CFC's?

2) Is it possible to run the second sup720 in a non redundant mode, non failover mode, as I've also seen that if it has been configured in a redundant mode, the two uplinks port state on the standby sup720 can affect the active sup720's uplink ports states?

3)Will the addition of the secondary Sup720 affect the flow of traffic to the ACE Module?

[Jon Marshall]

Brandon

I haven't costed these sort of things up lately but a supervisor seems a very expensive way of getting a couple of additonal ports for uplinks.

There may be other reasons but why not simply buy a fiber module for each chassis instead of supervisors ?

The advantage would be if you then needed more throughput from your other switches you have spare ports to use.

Jon

[bdyzel123]

Hi Jon,

We already have the two extra SUP's.

So if we can make use of them in this way, and possibly gain additional benefits out of it, it would be more cost effective than buying the extra fibre modules, which I whole heartedly agree would be the better solution if the budget supported it.

[Joseph W. Doherty]

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Posting

Yes, you can use all both sups ports.  (6500s are "nicer" than the 4500s in this.)

The 2nd sup, if a sup720, not VS-S720, will otherwise only be used to "backup" the actively running sup.  The latter, of course, is often more often why a 2nd sup is installed rather than to obtain its few additional ports.  (NB: a second VS-S720 does seem assist CFC forwarding.)

[bdyzel123]

Hi,

Thank you for the reply.

Just to make sure I understand you correctly, if we add the additional SUP720's, with our dual chassis, single SUP720 design, the additional ports will work, an forward all traffic to the CFC's, and other MSFC? I read that if the one SUP's NIC ports fail, then the backup SUP720's port is also affected, is this correct?

[Joseph W. Doherty]

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Yes, you understand me correctly.  (BTW, if I were mistaken, usually someone else would have posted a correction.)

Do you have an on-line reference to what you read?

[bdyzel123]

I'm not sure if this article is in line with my current scenario, but as I mentioned, I went and did a lot of reading from different sources in order to try and determine what the affects of adding the additional SUP720 to our production environment would have.

http://www.cisco.com/c/en/us/support/docs/switches/catalyst-6000-series-switches/24361-155.html#topic2

**Entry omitted**

This induces several limitations in the MSFC configuration. The first is that both MSFCs must have the same ACL configuration and must be applied on the same VLAN interfaces. Failure to do this will result in undesired and unpredictable scenarios.

For Catalyst 6000 switches with dual SUP II/PFC 2/MSFC 2, the responsibilities of the designated MSFC are as follows:

• programming the ACL in the hardware TCAM
• downloading the Cisco Express Forwarding (CEF) table from the MSFC 2 to the hardware Forwarding Information Base (FIB) of the active PFC 2

**Entry omitted**

All interfaces must have the same administrative/operational status. If an interface is up on one MSFC, it must be up the second as well (cannot be shutdown on one and up on the other).

**Entry omitted**

[Joseph W. Doherty]

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Ah, you're reading some really old stuff (notice the date on the article).  Your reference is about hybrid mode, the 6000 chassis, and using the sup1As or sup2s.  Yea, there might be some port limitations in that.  I'm been assuming, you'll be runing dual sup720s in native mode on a 6500 chassis.  If so, it should work as I've already described.

[johnnylingo · Accepted solution]

Wth the SUP32 and SUP720 families, the ports on the standby sup are fully available and will function just like any other line card. 

Where I'm a bit confused is this statement:

"When the second sup720 is added we would like to etherchannel the 1st  sup720 to distribution switch 1, and the second sup720 to distribution  switch 2"

Unless you're using VSS, you can't build an Etherchannel to different chassis.  You would build EtherChannels to both supervisors like this:

6509 #1: 5/1 + 6/1 = Distribution Switch 1, 5/2 + 6/2 = Distribution Switch 2.

6509 #2: 5/1 + 6/1 = Distribution Switch 1, 5/2 + 6/2 = Distribution Switch 2

Failover would then be happening via Spanning-Tree if they are Layer 2 links, or via routing if they are Layer 3.

[bdyzel123]

That sounds more effective, and I did notice the recommendations for that, but first wanted to confirm if adding the second SUP720 would keep the physical port communication separate even if the second SUP  is added, and if the config of the initial SUP would effect this.