Purpose
After you have configured the label-switched path (LSP), issued the show mpls lsp extensive command, and determined that there is an error, you might find that the error is not in the physical, data link, or Internet Protocol (IP) and interior gateway protocol (IGP) layers. Continue investigating the problem at the RSVP layer of the network.
Figure 19 illustrates the RSVP layer of the layered MPLS model.
Figure 19: Checking the RSVP Layer
With this layer, you check that dynamic RSVP signaling is occurring as expected, neighbors are connected, and interfaces are configured correctly for RSVP. Check the ingress, egress, and transit routers.
If the network is not functioning at this layer, the LSP does not work as configured.
Figure 20 illustrates the MPLS network used in this Find the appropriate term to place here instead of the word “chapter”..
Figure 20: MPLS Network Broken at the RSVP Layer
The network shown in Figure 20 is a fully meshed configuration where every directly connected interface can receive and send packets to every other similar interface. The LSP in this network is configured to run from ingress router R1, through transit router R3, to egress router R6. In addition, a reverse LSP is configured to run from R6 through R3 to R1, creating bidirectional traffic.
However, in this example, the LSP is down without a path in either direction, from R1 to R6 or from R6 to R1.
The crosses shown in Figure 20 indicate where the LSP is broken. Some possible reasons the LSP is broken might include that dynamic RSVP signaling is not occurring as expected, neighbors are not connected, or interfaces are incorrectly configured for RSVP.
In the network in Figure 20, a configuration error on transit router R3 prevents the LSP from traversing the network as expected.
To check the RSVP layer, follow these steps:
Typically, you use the show mpls lsp extensive command to verify the LSP. However for quick verification of the LSP state, use the show mpls lsp command. If the LSP is down, use the extensive option (show mpls lsp extensive) as a follow-up. If your network has numerous LSPs, you might consider specifying the name of the LSP, using the name option (show mpls lsp name name or show mpls lsp name name extensive).
To determine whether the LSP is up, enter the following command from the ingress router:
user@R1> show mpls lsp extensive
Ingress LSP: 1 sessions
10.0.0.6
From: 10.0.0.1, State: Dn, ActiveRoute: 0, LSPname: R1-to-R6
ActivePath: (none)
LoadBalance: Random
Encoding type: Packet, Switching type: Packet, GPID: IPv4
Primary State: Dn
2 Oct 27 15:06:05 10.1.13.2: No Route toward dest [4 times]
1 Oct 27 15:05:56 Originate Call
Created: Wed Oct 27 15:05:55 2004
Total 1 displayed, Up 0, Down 1
Egress LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
Transit LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
user@R3> show mpls lsp extensive
Ingress LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
Egress LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
Transit LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
user@R6> show mpls lsp extensive
Ingress LSP: 1 sessions
10.0.0.1
From: 10.0.0.6, State: Dn, ActiveRoute: 0, LSPname: R6-to-R1
ActivePath: (none)
LoadBalance: Random
Encoding type: Packet, Switching type: Packet, GPID: IPv4
Primary State: Dn
Will be enqueued for recomputation in 22 second(s).
1 Oct 27 14:59:12 CSPF failed: no route toward 10.0.0.1 [4 times]
Created: Wed Oct 27 14:57:44 2004
Total 1 displayed, Up 0, Down 1
Egress LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
Transit LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
The sample output shows that the LSP is down in both directions, from R1 to R6, and from R6 to R1. The output from R1 shows that R1 is using a no-cspf LSP since it tried to originate the call without being able to reach the destination. The output from R6 shows that the Constrained Shortest Path First (CSPF) algorithm failed, resulting in no route to destination 10.0.0.1.
When an RSVP session is successfully created, the LSP is set up along the paths created by the RSVP session. If the RSVP session is unsuccessful, the LSP does not work as configured.
To verify currently active RSVP sessions, enter the following command from the ingress, transit, and egress routers:
user@R1> show rsvp session Ingress RSVP: 0 sessions Total 0 displayed, Up 0, Down 0 Egress RSVP: 0 sessions Total 0 displayed, Up 0, Down 0 Transit RSVP: 0 sessions Total 0 displayed, Up 0, Down 0 user@R3> show rsvp session Ingress RSVP: 0 sessions Total 0 displayed, Up 0, Down 0 Egress RSVP: 0 sessions Total 0 displayed, Up 0, Down 0 Transit RSVP: 0 sessions Total 0 displayed, Up 0, Down 0 user@R6> show rsvp session Ingress RSVP: 0 sessions Total 0 displayed, Up 0, Down 0 Egress RSVP: 0 sessions Total 0 displayed, Up 0, Down 0 Transit RSVP: 0 sessions Total 0 displayed, Up 0, Down 0
user@R1> show rsvp session Ingress RSVP: 1 sessions To From State Rt Style Labelin Labelout LSPname 10.0.0.6 10.0.0.1 Up 1 1 FF - 100768 R1-to-R6 Total 1 displayed, Up 1 , Down 0 Egress RSVP: 1 sessions To From State Rt Style Labelin Labelout LSPname 10.0.0.1 10.0.0.6 Up 0 1 FF 3 - R6-to-R1 Total 1 displayed, Up 1 , Down 0 Transit RSVP: 0 sessions Total 0 displayed, Up 0, Down 0 user@R3> show rsvp session Ingress RSVP: 0 sessions Total 0 displayed, Up 0, Down 0 Egress RSVP: 0 sessions Total 0 displayed, Up 0, Down 0 Transit RSVP: 2 sessions To From State Rt Style Labelin Labelout LSPname 10.0.0.1 10.0.0.6 Up 1 1 FF 100784 3 R6-to-R1 10.0.0.6 10.0.0.1 Up 1 1 FF 100768 3 R1-to-R6 Total 2 displayed, Up 2 , Down 0 user@R6> show rsvp session Ingress RSVP: 1 sessions To From State Rt Style Labelin Labelout LSPname 10.0.0.1 10.0.0.6 Up 1 1 FF - 100784 R6-to-R1 Total 1 displayed, Up 1 , Down 0 Egress RSVP: 1 sessions To From State Rt Style Labelin Labelout LSPname 10.0.0.6 10.0.0.1 Up 0 1 FF 3 - R1-to-R6 Total 1 displayed, Up 1 , Down 0 Transit RSVP: 0 sessions Total 0 displayed, Up 0, Down 0
Sample Output 1 from all routers shows that no RSVP sessions were successfully created, even though the LSP R6-to-R1 is configured. Continue investigating the problem in Verify RSVP Neighbors.
In contrast to Sample Output 1and to illustrate correct output, Sample Output 2 shows the output from the ingress, transit, and egress routers when the RSVP configuration is correct, and the LSP is traversing the network as configured. R1 and R6 both show an ingress and egress RSVP session, with the LSP R1-to-R6, and the reverse LSP R6-to-R1. Transit router R3 shows two transit RSVP sessions.
Display a list of RSVP neighbors that were learned dynamically when exchanging RSVP packets. Once a neighbor is learned, it is never removed from the list of RSVP neighbors unless the RSVP configuration is removed from the router.
To verify RSVP neighbors, enter the following command from the ingress, transit, and egress routers:
user@R1> show rsvp neighbor RSVP neighbor: 1 learned Address Idle Up/Dn LastChange HelloInt HelloTx/Rx MsgRcvd 10.1.13.2 10 1/0 9:22 9 64/64 32 user@R3> show rsvp neighbor RSVP neighbor: 2 learned Address Idle Up/Dn LastChange HelloInt HelloTx/Rx MsgRcvd 10.1.13.1 0 1/0 28:20 9 190/190 41 10.1.36.2 16:50 1/1 15:37 9 105/78 38 user@R6> show rsvp neighbor RSVP neighbor: 1 learned Address Idle Up/Dn LastChange HelloInt HelloTx/Rx MsgRcvd 10.1.36.1 17:30 1/1 16:15 9 104/78 39
user@R3> show rsvp neighbor RSVP neighbor: 2 learned Address Idle Up/Dn LastChange HelloInt HelloTx/Rx MsgRcvd 10.1.13.1 5 1/0 9:14 9 63/63 33 10.1.36.2 5 1/0 9:05 9 62/62 32 user@R6> show rsvp neighbor RSVP neighbor: 1 learned Address Idle Up/Dn LastChange HelloInt HelloTx/Rx MsgRcvd 10.1.36.1 5 1/0 8:54 9 61/61 32
Sample Output 1 shows that R1 and R6 have one RSVP neighbor each, R3. However, the values in the Up/Dn field are different. R1 has a value of 1/0 and R6 has a value of 1/1, indicating that R1 is an active neighbor with R3, but R6 is not. When the up count is one more than the down count, the neighbor is active; if the values are equal, the neighbor is down. The values for R6 are equal, 1/1, indicating that the neighbor R3 is down.
Transit router R3 knows about two neighbors, R1 and R6. The Up/Dn field indicates that R1 is an active neighbor and R6 is down. At this point it is not possible to determine if the problem resides with R3 or R6, because both neighbors are not active. Continue investigating the problem in Verify RSVP Interfaces.
In contrast to Sample Output 1 and to illustrate correct output, Sample Output 2 shows the correct neighbor relationship between transit router R3 and egress router R6. The Up/Dn field shows the up count to be one more than the down count, 1/0, indicating that the neighbors are active.
Display the status of each interface on which RSVP is enabled to determine where the configuration error occurred.
To verify the status of RSVP interfaces, enter the following command from the ingress, transit, and egress routers:
user@R1> show rsvp interface
RSVP interface: 3 active
Active Subscr- Static Available Reserved Highwater
Interface State resv iption BW BW BW mark
so-0/0/0.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/1.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/2.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
user@R3> show rsvp interface
RSVP interface: 3 active
Active Subscr- Static Available Reserved Highwater
Interface State resv iption BW BW BW mark
so-0/0/0.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/1.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/2.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
<<< Missing interface so-0/0/3.0
user@R6> show rsvp interface
RSVP interface: 4 active
Active Subscr- Static Available Reserved Highwater
Interface State resv iption BW BW BW mark
so-0/0/0.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/1.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/2.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/3.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
user@R1> show rsvp interface
RSVP interface: 3 active
Active Subscr- Static Available Reserved Highwater
Interface State resv iption BW BW BW mark
so-0/0/0.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/1.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/2.0 Up 1 100% 155.52Mbps 155.52Mbps 0bps 0bps
user@R3> show rsvp interface
RSVP interface: 4 active
Active Subscr- Static Available Reserved Highwater
Interface State resv iption BW BW BW mark
so-0/0/0.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/1.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/2.0 Up 1 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/3.0 Up 1 100% 155.52Mbps 155.52Mbps 0bps 0bps
user@R6> show rsvp interface
RSVP interface: 4 active
Active Subscr- Static Available Reserved Highwater
Interface State resv iption BW BW BW mark
so-0/0/0.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/1.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/2.0 Up 0 100% 155.52Mbps 155.52Mbps 0bps 0bps
so-0/0/3.0 Up 1 100% 155.52Mbps 155.52Mbps 0bps 0bps
Sample Output 1 shows that even though each router has interfaces that are up and have RSVP active, there are no reservations (Active resv) on any of the routers. In this example, we would expect at least one reservation on the ingress and egress routers, and two reservations on the transit router.
In addition, interface so-0/0/3 on transit router R3 is not included in the configuration. The inclusion of this interface is critical to the success of the LSP.
In contrast to Sample Output 1 and to illustrate correct output, Sample Output 2 shows the relevant interfaces with active reservations.
After you have checked RSVP sessions, interfaces, neighbors, and determined that there might be a configuration error, verify the RSVP protocol configuration.
To verify the RSVP configuration, enter the following command from the ingress, transit, and egress routers:
user@R1> show configuration protocols rsvp
interface so-0/0/0.0;
interface so-0/0/1.0;
interface so-0/0/2.0;
interface fxp0.0 {
disable;
}
user@R3> show configuration protocols rsvp
interface so-0/0/0.0;
interface so-0/0/1.0;
interface so-0/0/2.0; <<< Missing interface so-0/0/3.0
interface fxp0.0 {
disable;
}
user@R6> show configuration protocols rsvp
interface so-0/0/0.0;
interface so-0/0/1.0;
interface so-0/0/2.0;
interface so-0/0/3.0;
interface fxp0.0 {
disable;
}
The sample output shows that R3 has interface so-0/0/3.0 missing from the RSVP protocol configuration. This interface is critical for the correct functioning of the LSP.
Depending on the error you encountered in your investigation, you must take the appropriate action to correct the problem. In this example, an interface is missing from the configuration of router R3.
To correct the error in this example, follow these steps:
Sample Output
user@R3> edit
Entering configuration mode
[edit]
user@R3# edit protocols rsvp
[edit protocols rsvp]
user@R3# show
interface so-0/0/0.0;
interface so-0/0/1.0;
interface so-0/0/2.0; <<< Missing interface so-0/0/3.0
interface fxp0.0 {
disable;
}
[edit protocols rsvp]
user@R3# set interface so-0/0/3.0
[edit protocols rsvp]
user@R3# show
interface so-0/0/0.0;
interface so-0/0/1.0;
interface so-0/0/2.0;
interface fxp0.0 {
disable;
}
interface so-0/0/3.0; <<< Interface now included in the configuration
[edit protocols rsvp]
user@R3# commit
commit complete
Meaning
The sample output shows that the missing interface so-0/0/3.0 on transit router R3 is now correctly included at the [edit protocols rsvp] hierarchy level. This results in the possibility that the LSP might come up.
After taking the appropriate action to correct the error, the LSP needs to be checked again to confirm that the problem in the MPLS layer has been resolved.
To verify the LSP again, enter the following command on the ingress, transit, and egress routers:
user@R1> show mpls lsp extensive
Ingress LSP: 1 sessions
10.0.0.6
From: 10.0.0.1, State: Up, ActiveRoute: 1 , LSPname: R1-to-R6
ActivePath: (primary)
LoadBalance: Random
Encoding type: Packet, Switching type: Packet, GPID: IPv4
*Primary State: Up
Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt):
10.1.13.2 10.1.36.2
5 Oct 27 15:28:57 Selected as active path
4 Oct 27 15:28:57 Record Route: 10.1.13.2 10.1.36.2
3 Oct 27 15:28:57 Up
2 Oct 27 15:28:44 10.1.13.2: No Route toward dest[35 times]
1 Oct 27 15:05:56 Originate Call
Created: Wed Oct 27 15:05:56 2004
Total 1 displayed, Up 1, Down 0
Egress LSP: 1 sessions
10.0.0.1
From: 10.0.0.6, LSPstate: Up, ActiveRoute: 0
LSPname: R6-to-R1, LSPpath: Primary
Suggested label received: -, Suggested label sent: -
Recovery label received: -, Recovery label sent: -
Resv style: 1 FF, Label in: 3, Label out: -
Time left: 136, Since: Wed Oct 27 15:29:20 2004
Tspec: rate 0bps size 0bps peak Infbps m 20 M 1500
Port number: sender 1 receiver 39092 protocol 0
PATH rcvfrom: 10.1.13.2 (so-0/0/2.0) 6 pkts
Adspec: received MTU 1500
PATH sentto: localclient
RESV rcvfrom: localclient
Record route: 10.1.36.2 10.1.13.2 <self>
Total 1 displayed, Up 1, Down 0
Transit LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
Transit LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
user@R3> show mpls lsp extensive Ingress LSP: 0 sessions Total 0 displayed, Up 0, Down 0 Egress LSP: 0 sessions Total 0 displayed, Up 0, Down 0 Transit LSP: 2 sessions 10.0.0.1 From: 10.0.0.6, LSPstate: Up, ActiveRoute: 1 LSPname: R6-to-R1, LSPpath: Primary Suggested label received: -, Suggested label sent: - Recovery label received: -, Recovery label sent: 3 Resv style: 1 FF, Label in: 100672, Label out: 3 Time left: 152, Since: Wed Oct 27 15:16:39 2004 Tspec: rate 0bps size 0bps peak Infbps m 20 M 1500 Port number: sender 1 receiver 39092 protocol 0 PATH rcvfrom: 10.1.36.2 (so-0/0/3.0) 7 pkts Adspec: received MTU 1500 sent MTU 1500 PATH sentto: 10.1.13.1 (so-0/0/2.0) 7 pkts RESV rcvfrom: 10.1.13.1 (so-0/0/2.0) 7 pkts Explct route: 10.1.13.1 Record route: 10.1.36.2 <self> 10.1.13.1 10.0.0.6 From: 10.0.0.1, LSPstate: Up, ActiveRoute: 1 LSPname: R1-to-R6, LSPpath: Primary Suggested label received: -, Suggested label sent: - Recovery label received: -, Recovery label sent: 3 Resv style: 1 FF, Label in: 100656, Label out: 3 Time left: 129, Since: Wed Oct 27 14:53:14 2004 Tspec: rate 0bps size 0bps peak Infbps m 20 M 1500 Port number: sender 1 receiver 47977 protocol 0 PATH rcvfrom: 10.1.13.1 (so-0/0/2.0) 40 pkts Adspec: received MTU 1500 sent MTU 1500 PATH sentto: 10.1.36.2 (so-0/0/3.0) 7 pkts RESV rcvfrom: 10.1.36.2 (so-0/0/3.0) 7 pkts Record route: 10.1.13.1 <self> 10.1.36.2 Total 2 displayed, Up 2, Down 0
user@R6> show mpls lsp extensive
Ingress LSP: 1 sessions
10.0.0.1
From: 10.0.0.6, State: Up, ActiveRoute: 1 , LSPname: R6-to-R1
ActivePath: (primary)
LoadBalance: Random
Encoding type: Packet, Switching type: Packet, GPID: IPv4
*Primary State: Up
Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 20)
10.1.36.1 S 10.1.13.1 S
Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt):
10.1.36.1 10.1.13.1
6 Oct 27 15:22:06 Selected as active path
5 Oct 27 15:22:06 Record Route: 10.1.36.1 10.1.13.1
4 Oct 27 15:22:06 Up
3 Oct 27 15:22:06 Originate Call
2 Oct 27 15:22:06 CSPF: computation result accepted
1 Oct 27 15:21:36 CSPF failed: no route toward 10.0.0.1[50 times]
Created: Wed Oct 27 14:57:45 2004
Total 1 displayed, Up 1, Down 0
Egress LSP: 1 sessions
10.0.0.6
From: 10.0.0.1, LSPstate: Up, ActiveRoute: 0
LSPname: R1-to-R6, LSPpath: Primary
Suggested label received: -, Suggested label sent: -
Recovery label received: -, Recovery label sent: -
Resv style: 1 FF, Label in: 3, Label out: -
Time left: 119, Since: Wed Oct 27 15:21:43 2004
Tspec: rate 0bps size 0bps peak Infbps m 20 M 1500
Port number: sender 1 receiver 47977 protocol 0
PATH rcvfrom: 10.1.36.1 (so-0/0/3.0) 7 pkts
Adspec: received MTU 1500
PATH sentto: localclient
RESV rcvfrom: localclient
Record route: 10.1.13.1 10.1.36.1 <self>
Total 1 displayed, Up 1, Down 0
Transit LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
Sample Output 1 from ingress router R1 shows that LSP R1-to-R6 has an active route to R6 and the state is up.
Sample Output 2 from transit router R3 shows that there are two transit LSP sessions, one from R1 to R6 and the other from R6 to R1. Both LSPs are up.
Sample Output 3 from egress router R6 shows that the LSP is up and the active route is the primary route. The LSP is now traversing the network along the expected path, from R1 through R3 to R6, and the reverse LSP, from R6 through R3 to R1.
