Re: MTU Backbone

sebastien3 · ‎03-11-2023

Hello,

On an ISP network, good practice is to switch the backbone to an MTU of 9000 on the access interfaces between the different equipment.

Should we pass the sub-interfaces (VLAN) or access interface that allow to form the IGP with BGP/EIGRP processes by configuring an MTU of 9000 ?

The recommendation would be that the MTU be deployed consistently across the backbone. Agree on that ?

I am going to reproduce a complete lab with 2 ASR 1000 routers and 4 Catalyst 4500 switches with interconnection 1G and 10G link .

Thanks

MHM Cisco World · ‎03-11-2023

follow

marce1000 · ‎03-11-2023

@MHM Cisco World Sorry but I thought we would be past that by now (= follow ?)

M.

-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '

marce1000 · ‎03-11-2023

- You may find this thread informative : https://community.cisco.com/t5/routing/disadvantages-of-increasing-mtu-router-buffers/td-p/3896463

M.

-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '

sebastien3 · ‎03-12-2023

@marce1000 Thanks, but that doesn't really answer my question...

I'm trying to figure out if I should do this :

SW1 Ten1/1---- Ten1/1 SW2 => MTU 9198

This connection between the switches is a trunk port.

Now I connect an ASR router on each switch and use VLAN 11 for BGP, do I also need to configure the switch and router interfaces to 9198 ? The ASR accepts an MTU of 9216.