3570 vs 6500 switches and teaming/clustering

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Jul 13th, 2006
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Hello, we seem to have an issue regarding behaviour on 3750 vs 6500 series switches, and wonder if anyone can help.

At a previous location, each 1 of 3 servers srv001a/b/c had a network connection into 2 separate Cisco 3570 switches, and these connections were teamed at the server using HP's network configuration tool. Each of these teamed connections across all 3 servers were then clustered together using Microsoft's Network Load Balancing to provide a single IP address for the virtual server srv001.

When we moved the servers to a new location and plugged the NICs into the 2 separate Cisco 6500 series switches, we found that the virtual IP address was only contactable from the same VLAN (and it may in fact have only been the same VLAN on one of the 6500 switches).

The only way we have managed to make the clustered IP address (192.168.x.y) generally reachable was by shutting down the ports for the teamed NICs on one of the switches, and adding a manual arp entry for the clustered IP on both switches:

[...rest of config...]

arp 192.168.x.y 03bf.c0xx.yyzz ARPA

Does anyone have any idea what differences between the 3750s and 6500s might explain this behaviour?


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Aaron Harrison Fri, 07/14/2006 - 01:54
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The main difference would be that the 6500s are two logical entities - i.e. seperate switches.


The 3750s were probably connected with stackwise connectors which makes them a single switch.


With them acting as a single switch, it's possible to set up FEC (probably listed as PAGP/LACP/Etherchannel or Aggregated on your NIC software) bundles - is this the NIC teaming method you are using?


This won't be possible when connected to two 6500s - you would need to use 'failover only' type teaming methods.



Regards


Please rate helpful posts...

Aaron

billy.taylor Fri, 07/14/2006 - 02:32
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Thanks for the response Aaron. The 2 3750s were not stacked, but they were trunked together and, oh hang on... one difference is that the 3750s did not have a L3 interface on the vlan in question, a separate firewall (itself a HA active/passive pair) handled routing. In the current config, though, the 6500s are doing the routing and have been given configs as follows:


interface Vlan51

ip address 192.168.x.2 255.255.255.224

standby 51 ip 192.168.x.1

standby 51 priority 101

end


and


interface Vlan51

ip address 192.168.x.3 255.255.255.224

standby 51 ip 192.168.x.1

standby 51 priority 102

end


Is there some other magic I need to achieve what I want?


Thanks,

Billy.

gpulos Fri, 07/14/2006 - 03:18
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are the two 6500s trunked??


if not, put a trunk on them that allows the vlan of the server NICs.

billy.taylor Mon, 07/17/2006 - 02:57
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Yes, the are trunked already and other traffic is passing OK. Billy.

Wilson Samuel Mon, 07/17/2006 - 01:16
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Hi,


I guess you have you have configured the ports on the Cat6500 on L-3 mode.


Could you please paste the config from the VLAN and the ports from the Cat6500.


Regards,

Wilson Samuel



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