Contents

1   Description

This instruction describes how to change the Maximum Transmission Unit (MTU) size.

Default is 1452 bytes, as the system internal IPv6 tunnels add an overhead of 48 bytes.

The default value works for the widest variety of available Ethernet switching infrastructure hardware and there is in general no need to deviate from the default value.

Note:  

Changing the value in-service requires a cluster reboot, causing an interruption of service.

2   Procedure

2.1   Change Maximum Transmission Unit Size

Prerequisites

• No documents are required.
• No tools are required.
• The following conditions must apply:
  • The new MTU size is known.
  • The user has the System Security Administrator role.
  • An Ericsson Command-Line Interface (ECLI) session in Exec mode is in progress.

Steps

1. Navigate to EvipParam managed object, for example:

   >ManagedElement=NODE06ST,Transport=1,Evip=1,EvipParams=1,EvipParam=mtu

2. Enter Config mode:

   (EvipParam=mtu)>configure

3. Change the MTU size, for example:

   (config-EvipParam=mtu)>value=1280

4. Commit the setting:

   (config-EvipParam=mtu)>commit

5. Open up a console connection to SC-1, for example:

   ssh root@<hostname>

6. Perform a cluster reboot:
   Attention!

   Risk of system malfunction or traffic disturbance.

   Service is interrupted during a cluster reboot.

   SC-1:~ #cmw-cluster-reboot

   The following output is shown:

   Do you really want to reboot the entire cluster (yes/no)?

7. Enter yes to reboot.
8. Verify the MTU size of the traffic interface:

   SC-1:~ #ifconfig alb_tr

   The following is an example output:

   alb_tr Link encap:UNSPEC ⇒ HWaddr FE-80-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:10.118.160.53 P-t-P:10.118.160.53 Mask:255.255.255.255 inet6 addr: 2001:1b70:4292:8207::51/128 Scope:Global inet6 addr: fe80::3e19:7dff:fe0e:ab0c/64 Scope:Link UP POINTOPOINT RUNNING NOARP MTU:1280 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:19954 errors:4 dropped:4 overruns:0 carrier:0 collisions:4 txqueuelen:0 RX bytes:0 (0.0 b) TX bytes:9443431 (9.0 Mb)

9. Verify the MTU size of the authentication interface:

   SC-1:~ #ifconfig alb_aut

   The following is an example output:

   alb_aut Link encap:UNSPEC ⇒ HWaddr FE-80-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:10.118.160.43 P-t-P:10.118.160.43 Mask:255.255.255.255 inet6 addr: fe80::3e19:7dff:fe0e:ab0c/64 Scope:Link inet6 addr: 2001:1b70:4292:8207::43/128 Scope:Global UP POINTOPOINT RUNNING NOARP MTU:1280 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:2 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 b) TX bytes:232 (232.0 b)