[c-nsp] MTU settings/GRE tunnel

[Nick Kraal]

Dear all,

We are setting up tunnels within our network, and are using some 
previous documented configurations for this. We will use this to enable 
virtual P2P BGP sessions to isolate certain parts of our routing table. 
Cheap, temporary, and fast.

interface Tunnel0
  ip address 192.168.100.9 255.255.255.252
  no ip unreachables
  no ip proxy-arp
  ip mtu 1524
  tunnel source Loopback1
  tunnel destination 10.10.10.10

Is there any information/advice/rule-of-thumb on setting the MTU size on 
the tunnel interface?

Thanks in advance,

-nick/