![](/images/new-backgrounds/1185470/185470225x1.webp)
Default MTUs for framing protocols are:
•Frame Relay: 4352 bytes
•HDLC: 4352 bytes
•
MTU discovery facility
MTU sizes are generally selected at the host end of the route. This is accomplished by turning on the host’s MTU discovery facility and allowing the host to send packets. The MTU discovery facility operates by default on the SP Switch Router. AIX4.3.1 provides MTU discovery; however, you have to enable it with the /etc/no command.
In effect, the discovery facility tells the router not to fragment, but instead to advise the host when the packet size is larger than the given path can handle. This allows the host to discover the largest packet that the most restrictive of the media components within the same path can handle. Once "discovered", the host then sends only packets in sizes matching the reported maximum, and so packets are not fragmented.
3.10.3 Putting grifconfig.conf Additions into Effect
Additions made to /etc/grifconfig.conf after
Use the grreset command to reset each configured SP Switch Router Adapter card by specifying the slot number where each card is installed, as follows:
grreset <card_slot_number>
3.11 Step 3. Change Profile Settings
As mentioned, this step is optional and explained in detail in GRF 400/1600 Configuration Guide 1.4,
3.12 Step 4. Run dev1config
If you followed the advice in Section 3.10.1, “Method 1: Use SP SNMP Manager - Recommended” on page 89, running the command dev1config should be all that needs to be done.
Installation and Configuration | 95 |