User manual

xStack DGS/DXS-3300 Series Layer 3 Stackable Gigabit Ethernet Switch User Manual
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Router Links Advertisements
Router links advertisements are type 1 link state advertisements. Each router in an area originates a routers links
advertisement. The advertisement describes the state and cost of the router’s links to the area. All of the router’s links to
the area must be described in a single router links advertisement.
The format of the Router Links Advertisement is shown below:
Link-State Age
Options Link-State Type
Link-State ID
Advertising Router
Link-State Sequence Number
Link-State Checksum
Length
Routers Links Advertisements
Reserved Reserved Number of Links
Link ID
Link Data
Type No. Of TOS TOS 0 Metric
TOS
Metric
...
TOS
Metric
...
Link ID
Link Data
0
0
VBE
Figure 6- 136. Routers Links Advertisements
In router links advertisements, the Link State ID field is set to the router’s OSPF Router ID. The T - bit is set in the
advertisement’s Option field if and only if the router is able to calculate a separate set of routes for each IP Type of Service
(TOS). Router links advertisements are flooded throughout a single area only.
Field Description
V - bit When set, the router is an endpoint of an active virtual link that is
using the described area as a Transit area (V is for Virtual link
endpoint).
E - bit When set, the router is an Autonomous System (AS) boundary
router (E is for External).
B - bit When set, the router is an area border router (B is for Border).
Number of Links The number of router links described by this advertisement. This
must be the total collection of router links to the area.