Riverstone Networks WICT1-12 - Manual (Page 240)

15-6 Riverstone Networks RS Switch Router User Guide Release 8.0
Setting IS-IS Interface Parameters IS-IS Configuration Guide
15.5.2 Setting Interface Parameters for a Designated Intermediate System (DIS)
On a broadcast network, routers elect a DIS, which advertises all links to the attached routers. The following
parameters are used during DIS election and by the interface, if it is elected as the DIS. These parameters can be set
globally, or for Level-1 or Level-2 interfaces only.
• Priority
The router’s priority for the Designated Intermediate System (DIS) election. The router with the highest priority
becomes the DIS. To ensure that a router does not become the DIS, set this parameter to 0. To increase a router’s
chance of becoming a DIS, set this parameter to the highest value, which is 127. In case of a tie, the router with
the highest System ID becomes the DIS. To The default priority is 1.
• DIS Hello Interval
The hello-interval used if the router becomes the DIS. The default hello-interval is 3.
• CSN Interval
The interval at which the router will multicast Complete Sequence Number PDUs (CSNPs), if the router becomes
the DIS. CSNPs contain a list of all LSPs in the database in addition to information used by the other routers to
determine whether they have synchronized LSP databases. The default csn-interval is 10.
15.5.3 Setting IS-IS Interface Timers
The IS-IS protocol uses a variety of timers, some of which can be modified at the interface level. The timers have
default values which you can change when needed. These are as follows:
• Hello Interval
The interval at which hello packets are sent.
• Hello Multiplier
The number of hello-intervals a router does not receive a hello-packet from its neighbor before it considers its
neighbor as down.
• LSP Interval
The interval between the transmission f LSPs.
• Retransmit Interval
The interval a router waits before it retransmits an LSP.
15.5.4 Setting Mesh Group Membership
The
mesh-group
parameter allows for the assignment of interfaces to mesh groups, as defined in RFC 2973. Mesh
groups are used within full-mesh, point-to-point topologies to limit the amount of flooding of LSPs. Each interface in
a particular mesh group will not forward an LSP if the LSP is received on a port that belongs to that mesh group. Mesh
groups are identified by numbers, and range from 0 to 2147483647. Assigning an interface to mesh group 0 (zero),
sets that interface to not forward any LSPs, regardless of the interface on which it is received.
The following is an example of assigning a set of interfaces to mesh groups:
rs(config)# isis set interface gig1 mesh-group 10
rs(config)# isis set interface gig2 mesh-group 10
rs(config)# isis set interface gig3 mesh-group 10
rs(config)# isis set interface gig4 mesh-group 0