Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

6500 Redundant Sup720 IOS upgrade Question


First, here is the setup:

2 6500's with dual Sup 720's connected together with dual Gigabit etherchannel 802.1Q trunks. Redundancy mode is SSO/NSF and they run in native mode

Each router runs HSRP for the VLANS shared between them. One is active for all the VLANS, the other standby for all the VLANS. Rapid spanning-tree is used to decrease spanning-tree topology change times.

Most hosts connected to theses routers are single-connected to one or the other.

NSF is enable on EIGRP which is the site routing protocol

Distribution-layer switches are dual-connected to both routers

My basic question is what is the best way to upgrade the IOS on the switches to eliminate or minimize loss of network connectivity? On 4500's, I can use ISSU to do 0 downtime updates, but the only reference to ISSU in the 6500's I can find always mentions modular IOS patches. I am not opposed to moving to modular IOS if that is required, but I am unsure if Modular IOS can do a 0 downtime IOS upgrade.

Thanks for any responses

Nathan Spitzer

Cisco Employee

Re: 6500 Redundant Sup720 IOS upgrade Question


Cat6500 supports partial ISSU on 6500 with modular IOS. Why do you want to upgrade the IOS ?

1. Are you facing some software issues with the present IOS?

2. Is there any new hardware support that you are looking for ?

3. Are you looking for some new features support on the new IOS?

What is the current code that you are running and the one you want to upgrade?

I would suggest you not to upgrade the IOS untill and unless it is a critical business requirement.

The best way for you to upgrade the IOS is to have the standby chassis upgraded first and once it is completely done shift the traffic to this chassis. Upgrade the other chassis afterwards the same way as was done on the other chassis.


-amit singh

New Member

Re: 6500 Redundant Sup720 IOS upgrade Question

This was a "forward-looking" question but there are 2 new features out that we need. Currently we run 12.2(18)SXF11. The reasons we need to upgrade are:

1) LLDP support. Supporting LLDP greatly simplifies our Nortel VOIP phone system by removing the requirement that the phones get their voice VLAN from a data (native) vlan dhcp server

2) 802.1x MDA, which allows a voip phone and an attached data device to be independently authenticated on a port-by-port bases. Note: This is not released yet on the 6500's, but our sales engineer indicates it will be released late 1'st quarter which means August or later we would upgrade

3) Contractual requirements: We have a contract with a goverment agency which specifies all equipment thier data runs over will be free of known security vulnerabilities, even where our configuration means we are not vulnerable. If a vulnerability is found we have 30 days to update to a fixed version so any day now I could have a fire-drill requiring an update.

CreatePlease to create content