Figure 511 Sample Network for the SPF Processing Example

Links and A'—'C have a cost of 30; all other links have a cost of 10. The tunnel from Router

A to Router E has been configured with tunnel mpls traffic-eng autoroute metric 1. This means that the cost to get to Router E is 1, the cost to get to Router F is 11, and the cost to get to Router G is also 11.

But what about the costs to Routers B, C, and D? If the tunnel from Router A to Router E had a metric of 1 when the tunnel was put in the TENT list, the SPF would look something like this:

PATH List

TENT List

{A,0,0}

{E,1,Tunnel0}

{B,30,B}

{C,30,C}

PATH List

TENT List

{A,0,0}

{D,11,Tunnel0}

{E,1,Tunnel0}

{F,11,Tunnel0}

{G,11,Tunnel0}

{B,30,B}

{C,30,C}

In the next table, {B,30,B} and {C,30,C} are removed from the TENT list because, as far as SPF is concerned, {B,21,Tunnel0} and {C,21,Tunnel0} are the shortest paths to Routers B and C.

PATH List

TENT List

{A,0,0}

{F,11,Tunnel0}

{E,1,Tunnel0}

{G,11,Tunnel0}

{D,11,Tunnel0}

{B,21,Tunnel0}

{C,21,Tunnel0}

{B,30,B}

{C,30,C}

PATH List

TENT List

{A,0,0}

<Empty>

{E,1,Tunnel0}

{D,11,Tunnel0}

{B,21,Tunnel0}

{C,21,Tunnel0}

{F,11,Tunnel0}

{G,11,Tunnel0}

Table 5-17 shows the resulting routing table.

Table 5-17 shows the resulting routing table.

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