D-Link xStack Reference Manual page 223

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xStack DGS-3620 Series Layer 3 Managed Stackable Gigabit Switch Web UI Reference Guide
E
Parameter
Network Mask
E-bit
Forwarding Address
TOS
Metric
External Route Tag
Including the NSSA
The NSSA or Not So Stubby Area is a feature that has been added to OSPF so external routes from ASs
(Autonomous Systems) can be imported into the OSPF area. As an extension of stub areas, the NSSA feature
uses a packet translation system used by BRs (Border Routers) to translate outside routes into the OSPF area.
Consider the following example:
AS External Link Advertisements
Link-State Age
Link-State Sequence Number
Link-State Checksum
TOS
Forwarding Address
External Route Tag
Figure 6-39 AS External Link Advertisements
Description
The IP address mask for the advertised destination.
The type of external metric. If the E-bit is set, the metric specified is a Type 2 external
metric. This means the metric is considered larger than any link state path. If the E-bit
is zero, the specified metric is a Type 1 external metric. This means that is comparable
directly to the link state metric.
Data traffic for the advertised destination will be forwarded to this address. If the
Forwarding Address is set to 0.0.0.0, data traffic will be forwarded instead to the
advertisement's originator.
The Type of Service that the following cost is relevant to.
The cost of this route. The interpretation of this metric depends on the external type
indication (the E - bit above).
A 32-bit field attached to each external route. This is not used by the OSPF protocol
itself.
Options
Link-State ID
Advertising Router
Network Mask
Metric
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Length