H3C Technologies H3C S12500 Series Switches - Manual (Page 86)

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An AS external LSA originates from an ASBR, and describes routing information to a destination
outside the AS.
Figure 35 AS external LSA format
Major fields of the AS external LSA are as follows:
{
Link state ID—he IP address of another AS to be advertised. When describing a default route,
the Link state ID is always set to default destination (0.0.0.0) and the network mask is set to
0.0.0.0.
{
Network mask—The IP address mask for the advertised destination.
{
E (External Metric)—The type of the external metric value, which is set to 1 for type 2 external
routes, and set to 0 for type 1 external routes. For description of external route types, see "
Route
types ."
{
Metric—The metric to the destination.
{
Forwarding address—Data traffic for the advertised destination is forwarded to this address.
{
External route tag—A tag attached to each external route. This is not used by OSPF. It can be
used to manage external routes.
• NSSA external LSA
An NSSA external LSA originates from the ASBR in an NSSA, and is flooded in the NSSA area
only. It has the same format as the AS external LSA.