If a cisco ios router is configured with mtu x and is connected to a cisco ios xr router, then the corresponding interface on the cisco ios xr router should be configured with mtu x+14 for ethernet interfaces, or mtu x+4 for serial interfaces.. Hi there, we have cisco 3845 router connect to 2920 router via gre tunnel. now the size in 3845 is 1500 bytes while 17904 in 2900 serial router. is any command available to reduce the mtu size to 1500 in 2921 router?. Hi, all. i am trying to change the regular mtu value on a vlan interface. this is how the setup looks like. rsm running ios ver 12.2(6a) in slot 4 on a catalyst 5500 switch..
Between two cisco switches you don’t need to change the link layer mtu, but if you have a cisco switch talking to a third party switch that can not handle an mtu size of 1522 (which cisco switches can), then you can use the mtu command under the vlan to accommodate that.. Important note: cisco routers do not have the capability to change mtu (maximum transmit unit) size directly.instead you must change the mss (maximum segment size) which is always 40 bytes smaller. This 871 is at a remote site and is an ezvpn ipsec client (network extension mode) back to a 3030 headend. we're having problems with a pc trying to connect through the ipsec tunnel and we think it may be an mtu size problem..
