BigIron RX Series Configuration Guide 89153-1001810-01Globally configuring IS-IS on a device 29Changing the LSP interval and retransmit intervalYou LSP interval is the rate of transmission, in milliseconds of the LSPs. The retransmit interval isthe time the device waits before it retransmits LSPs. To define an LSP interval, enter a commandsuch as the following.BigIron RX(config-isis-router)# lsp-interval 45Syntax: [no] lsp-interval Enter 1 – 4294967295 milliseconds for the LSP interval. The default is 33 milliseconds.To define an interval for retransmission of LSPs enter a command such as the following.BigIron RX(config-isis-router)# etransmit-interval 3Syntax: [no] retransmit-interval Enter 0 – 65535 seconds for the retransmission interval. The default is 5 seconds.Changing the SPF timerEvery IS maintains a Shortest Path First (SPF) tree, which is a representation of the states of eachof the IS’s links to ESs and other ISs. If the IS is both a Level-1 and Level-2 IS, it maintains separateSPF trees for each level.To ensure that the SPF tree remains current, the IS updates the tree at regular intervals following achange in network topology or the link state database. By default, the device recalculates its IS-IStree every five seconds following a change. You can change the SPF timer to a value from 1 – 120seconds.To change the SPF interval, enter a command such as the following.BigIron RX(config-isis-router)# spf-interval 30Syntax: [no] spf-interval The parameter specifies the interval and can be from 1 – 120 seconds. The default is 5seconds.Globally disabling or re-enabling hello paddingBy default, the device adds extra data to the end of a hello packet to make the packet the samesize as the maximum length of PDU the device supports.The padding applies to the following types of hello packets:• ES hello (ESH PDU)• IS hello (ISH PDU)• IS to IS hello (IIH PDU)The padding consists of arbitrarily valued octets. A padded hello PDU indicates the largest PDU thatthe device can receive. Other ISs that receive a padded hello PDU from the device can thereforeensure that the IS-IS PDUs they send the device. Similarly, if the device receives a padded helloPDU from a neighbor IS, the device knows the maximum size PDU that the device can send to theneighbor.When padding is enabled, the maximum length of a Hello PDU sent by the device is 1514 bytes.
