MPLS-failure of aggregation route to LSP-advanced feature

MPLS-failure of aggregation route to LSP-advanced feature
A fec will only assign tags to the same route. The meaning of the same route: The same prefix and the same mask. A typical situation will damage this rule: summary. When it comes to details, distribution is a summary. Although it complies with the routing Search rules, the large network segment contains small network segments, but for FEC, it destroys the FEC model. Routes are summarized in the MPLS domain. C is the summary point. route summary will destroy the aggregation of routes that are not the same in the MPLS domain (the prefix/mask are absolutely the same). After aggregation, a fec is divided into two ends based on the aggregation point. in the preceding figure, a route is returned from Router E. 10.1.1.0/24, the 24-bit mask is uploaded to D, and finally to C. At this time, C makes A summary and summarizes the/16-bit mask from C to B, and B to. the premise is that C only sends the summary route to suppress the detailed route. in this way, the LSP has been destroyed into two segments. finally, data streams are forwarded in the MPLS domain, from one LSP to two LSP. use router C as the demarcation point. non-link aggregation, a complete FEC path: In the following topology, R4 has a loopback port. 44.1.1.1/32R5 also has a loopback port: During the 55.1.1.1/32 period, R4, R1, R2, R3, R5, all devices have the same understanding of the two routes (with the same mask, to form a prerequisite for completing the FEC link. from R4 to R 5 is a path, which can be viewed through traceroute: From the traceroute result, for the 55.1.1.1 above R4, the label allocated by R1 is 102. r2 assigns 202 labels for 55.1.1.1. r3 assigns 302 labels for 55.1.1.1. in R5, because 55.1.1.1/32 is directly connected, the assigned tag is implict-null (3), an empty tag. therefore, the traceroute path is label: 102 --> 202 --> 302 --> (3) implict-null. The entire path is a path. no link aggregation is performed. link aggregation: an incomplete FEC path. In the following topology, R4 has a loopback port. 44.1.1.1/32R5 also has a loopback port: 55.1.1.1/32 now, R1, 2, 3, 4, 5. We will make a route aggregation in the middle, so that the five devices do not have a uniform understanding of the prefix, see what happens. finally, R2 is selected for a route summary. route/32-bit to/24-bit. O SPF cannot be summarized in the same region, so the environment needs to be slightly transformed, R2--R3--R5 belongs to area 1. in the ospf process above R2, perform a route Summary of 55.1.1.1/32 ---> 55.1.1.0/24 for area1. it is finally advertised to R1 and R4, which means that the Routes learned on R1 and R4 are 24 bits for 55.1.1.0/24 instead of 32 bits. Finally, the result of R4 traceroute 55.1.1.1 is: here we can see that the data packet of R4 reaches R1, And the label assigned by R1 to 55.1.1.0/24 is 100. when the packet arrives at R1, R2 is directly connected because 55.1.1.0/24. Therefore, an empty tag is assigned to R1.R1 to remove the 100 tag. send the IP packet to R2.R2 to obtain the IP packet. After query, the packet is sent to 55.1.1.1, which has a route of 55.1.1.1/32, r3 will assign a label 30x to R2. at this time, R2 will push the IP packet into the label 30x and then enter the MPLS Forwarding process. r2 is pushed into the 30x label and sent to R3. Because 55.1.1.1/32 on R5 is a direct connection route, R5 will assign an empty label (3) to the prefix and (3) distribution to R3. so when the MPLS packet is sent to R3, R3 will remove the 30x before, and then remove the label and directly send the IP packet to R5. therefore, a complete LSP, it is finally divided into two disconnections. Take R2 as the demarcation point. the following describes the entire process of tag publishing on time: Finally, we will sort out the tag distribution process: 1. R4 sends the message above: R4. In the routing table, 55.1.1.x/24 is 24 bits, because R2 summarizes area1, there will be no 32-bit routing details: On R4, the outgoing label should be allocated by R1 for 55.1.1.0/24: in this way, the IP package enters R4, then R4 pushes a 100 tag. forward the MPLS packet to R1.2 and R1 forward the MPLS packet. the prefix of 55.1.1.0/24 on R1 is the label assigned by R2. because 55.1.1.0/24 is generated by R2 and can also be considered as a direct connection route of R2, R2 will assign an empty label to R1.R1 and now it receives an MPLS packet labeled 100, the action is to pop up the tag. because R1 is allocated with a (3) label for 55.1.1.0/24, it is implicitly empty. therefore, R1 receives the related 100 tag message and pops up directly. Then, it sends the message to R2. = through the eth0/0 interface. ============ Now, the first LSP is complete below is the second LSP ==================================== ========= 3, r2 receives the IP packet, continues to PUSH, and forwards the MPLS packet to R3.R2. At this time, it receives a packet. the destination address is 55.1.1.1.IP. When MPLS is generated, it should query the cef table: the labels assigned by R3 for the 55.1.1.1/32 route prefix are 302. r2 will PUSH 302 to the IP package as the exit. then, e1/0 is forwarded to R3.4. R3 receives the MPLS packet, pops out the label, and forwards the packet to r51. 55.1.1.1/32 is the R5 direct connection route, therefore, R5 will assign an empty label (3) to the LDP neighbor R3.MPLS, mpls out, and check the label forwarding table of R3: When R3 receives an MPLS packet with a label of 302, it will pop up the label, then, use Et0/0 to send a pure IP packet to R5. final R 5. received the relevant IP packet and directly connected to the local route. One-way communication. Therefore, the final test result is: