D-Link DES-3326SRM Product Manual - Page 184
Autonomous Systems External Link Advertisements, Table 13. AS External System Advertisement
UPC - 790069255304
View all D-Link DES-3326SRM manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 184 highlights
D-Link DES-3326S Layer 3 Switch Autonomous Systems External Link Advertisements Autonomous Systems (AS) link advertisements are Type 5 link state advertisements. These advertisements are originated by AS boundary routers. A separate advertisement is made for each destination known to the router, that is external to the AS. AS external link advertisements usually describe a particular external destination. For these advertisements the Link State ID field specifies an IP network number. AS external link advertisements are also used to describe a default route. Default routes are used when no specific route exists to the destination. When describing a default route, the Link Stat ID is always set the Default Destination address (0.0.0.0) and the Network Mask is set to 0.0.0.0. The format of the AS External Link Advertisement is shown below: AS External Link Advertisements Link-State Age Options 5 Link-State ID Advertising Router Link-State Sequence Number Link-State Checksum Length E TOS Network Mask Metric Forwarding Address External Route Tag Table 13. AS External System Advertisement Field Network Mask E - bit Forwarding Address TOS Metric External Route Tag 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. 174