[c-nsp] Enabling Jumbo Frames with Mainframes

[Dale W. Carder]

Thus spake Ruben Montes (Ruben.Montes at eu.didata.com) on Fri, Aug 05, 2005 at 09:43:38AM +0200:
> I need some help becasuse this is related with IBM Mainframes and I don't have any experience with them.
> There some Mainframes connected to a Cisco backbone network with Cat6500 with sup720 IOS 12.2(18)SXD2. IBM engineers want to enable Jumbo frames (don't ask me why) in the mainframes, so I understand I should also configure this feature in the 6500.
> What should I take care about? Customer is a banking company and these are very critical devices as you know...


I would worry about path mtu discovery and if you have any 
firewalls that make poor decisions about icmp traffic.

I would worry what routers may have to chew up cpu time dealing
with fragments.

Other than that, I also recall a note in the release notes
about handling multicast in hardware if the ingress and
egress mtu's were different.

Maybe I'd be more concerned about running SXD2....

Dale

----------------------------------
Dale W. Carder - Network Engineer   
University of Wisconsin at Madison  
http://net.doit.wisc.edu/~dwcarder