HP 200 Series Services And Applications page 175

DECnet Routing Service
Routing Table Maintenance
Routing Table Maintenance
DECnet routers maintain their routing tables by multicasting routing
messages to adjacent routers. A level 1 routing message is periodically
multicast to adjacent routers in the same area. The level 1 routing message
contains the sending router's current information on the routes to all nodes
in the area. A level 2 routing message is periodically multicast to adjacent
level 2 routers whether or not they are in the same area. The level 2 routing
message contains the sending router's current information on the routes to
all areas. When a router receives a routing update message, it may or may
not update its routing table based on whether the router learns of a new
destination node or area or a lower-cost path.
On HP routers, routing messages are multicast every 3 minutes by default.
However, a period as short as every 15 seconds can be configured by modify-
ing the Bcast. Routing Timer parameter using the Configuration Editor.
Connecting to Routers from DEC
HP routers use the HDLC data-link layer protocol when connected together
over point-to-point links. DEC routers use the DDCMP data-link layer proto-
col over point-to-point links. These protocols are not compatible. Therefore,
you cannot connect DEC routers to HP routers over a point-to-point serial
link. You must use either an Ethernet or an X.25 link.
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