Verifying the IP Layer
Purpose
You can check the IP layer before or after you check the interior gateway protocol (IGP) layer, depending on whether you have OSPF or IS-IS configured as the IGP. If your MPLS network is configured with OSPF as the IGP, you must first verify the IP layer, checking that the interfaces have correct IP addressing and that the OSPF neighbors are established before you check the OSPF layer.
If you have IS-IS configured as the IGP in your MPLS network, you can verify either the IP layer or the IS-IS protocol layer first. The order in which you check the IP or IS-IS layer does not affect the results.
Figure 1: MPLS Network Broken at the IP Layer
The cross in Figure 1 indicates where the LSP is broken because of the incorrect configuration of an IP address on ingress router R1.
- Verify the LSP
- Verify IP Addressing
- Verify Neighbors or Adjacencies at the IP Layer
- Take Appropriate Action
- Verify the LSP Again
Verify the LSP
Purpose
After configuring the LSP, you must verify that the LSP is up. LSPs can be ingress, transit, or egress. Use the show mpls lsp command for quick verification of the LSP state, with the extensive option (show mpls lsp extensive) as a follow-up if the LSP is down. 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).
Action
To verify that the LSP is up, enter the following command from the ingress router:
user@host> show mpls lsp extensive
Sample Output 1
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
Will be enqueued for recomputation in 25 second(s).
44 Oct 15 16:56:11 CSPF failed: no route toward 10.0.0.6 [2685 times]
43 Oct 14 19:07:09 Clear Call
42 Oct 14 19:06:56 Deselected as active
41 Oct 14 19:06:56 10.1.12.1: MPLS label allocation failure
40 Oct 14 19:06:56 Down
39 Oct 14 18:43:43 Selected as active path
38 Oct 14 18:43:43 Record Route: 10.1.13.2 10.1.36.2
37 Oct 14 18:43:43 Up
[...Output truncated...]
Created: Thu Oct 14 16:04:33 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
Meaning
The sample output from ingress router R1 shows that an MPLS label allocation failure occurred and the Constrained Shortest Path First (CSPF) algorithm failed, resulting in no route to destination 10.0.0.6 on R6.
Verify IP Addressing
Purpose
When you investigate the IP layer, you verify that interfaces have correct IP addressing, and that OSPF neighbors or IS-IS adjacencies are established. In this example, an IP address is configured incorrectly on the ingress router (R1).
Action
To verify IP addressing, enter the following command from the ingress, transit, and egress routers:
Sample Output
user@R1> show interfaces terse
Interface Admin Link Proto Local Remote
so-0/0/0 up up
so-0/0/0.0 up up inet 10.1.12.1/30
iso
mpls
so-0/0/1 up up
so-0/0/1.0 up up inet 10.1.15.1/30
iso
mpls
so-0/0/2 up up
so-0/0/2.0 up up inet 10.1.13.2 <<< Incorrect IP address
iso
mpls
lo0 up up
lo0.0 up up inet 10.0.0.1
iso 49.0004.1000.0000.0001.00
user@R3> show interfaces terse
Interface Admin Link Proto Local Remote
so-0/0/0 up up
so-0/0/0.0 up up inet 10.1.34.1/30
iso
mpls
so-0/0/1 up up
so-0/0/1.0 up up inet 10.1.23.2/30
iso
mpls
so-0/0/2 up up
so-0/0/2.0 up up inet 10.1.13.2/30 <<< Identical to R1
iso
mpls
so-0/0/3 up up
so-0/0/3.0 up up inet 10.1.36.1/30
iso
mpls
lo0 up up
lo0.0 up up inet 10.0.0.3
iso 49.0004.1000.0000.0003.00
user@R6> show interfaces terse
Interface Admin Link Proto Local Remote
so-0/0/0 up up
so-0/0/0.0 up up inet 10.1.56.2/30
iso
mpls
so-0/0/1 up up
so-0/0/1.0 up up inet 10.1.46.2/30
iso
mpls
so-0/0/2 up up
so-0/0/2.0 up up inet 10.1.26.2/30
iso
mpls
so-0/0/3 up up
so-0/0/3.0 up up inet 10.1.36.2/30
iso
mpls
lo0.0 up up inet 10.0.0.6
iso 49.0004.1000.0000.0006.00
Meaning
The sample output shows that the IP addresses for interface so-0/0/2.0 on R1 and interface so-0/0/2.0 on R3 are identical. Interface IP addresses within a network must be unique for the interface to be identified correctly.
Verify Neighbors or Adjacencies at the IP Layer
Purpose
If the IP addressing is configured incorrectly then the OSPF neighbors or IS-IS adjacencies both need to be checked to determine if one or both of them are established.
Action
To verify neighbors (OSPF) or adjacencies (IS-IS), enter the following commands from the ingress, transit, and egress routers:
Sample Output 1
user@R1> show ospf neighbor extensive Address Interface State ID Pri Dead 10.1.12.2 so-0/0/0.0 Full 10.0.0.2 128 34 area 0.0.0.0, opt 0x42, DR 0.0.0.0, BDR 0.0.0.0 Up 1d 04:45:20, adjacent 1d 04:45:20 10.1.15.2 so-0/0/1.0 Full 10.0.0.5 128 35 area 0.0.0.0, opt 0x42, DR 0.0.0.0, BDR 0.0.0.0 Up 1d 04:45:20, adjacent 1d 04:45:10 <<< no adjacency with R3 so-0/0/2 user@R3> show ospf neighbor extensive Address Interface State ID Pri Dead 10.1.23.1 so-0/0/1.0 Full 10.0.0.2 128 35 area 0.0.0.0, opt 0x42, DR 0.0.0.0, BDR 0.0.0.0 Up 1w2d 04:54:30, adjacent 1w2d 04:54:21 10.1.36.2 so-0/0/3.0 Full 10.0.0.6 128 39 area 0.0.0.0, opt 0x42, DR 0.0.0.0, BDR 0.0.0.0 Up 1w2d 04:54:30, adjacent 1w2d 04:54:30 <<< no adjacency with R1 so-0/0/2 user@R6> show ospf neighbor extensive Address Interface State ID Pri Dead 10.1.56.1 so-0/0/0.0 Full 10.0.0.5 128 39 area 0.0.0.0, opt 0x42, DR 0.0.0.0, BDR 0.0.0.0 Up 1d 02:59:35, adjacent 1d 02:59:35 10.1.26.1 so-0/0/2.0 Full 10.0.0.2 128 36 area 0.0.0.0, opt 0x42, DR 0.0.0.0, BDR 0.0.0.0 Up 1w2d 04:57:30, adjacent 1w2d 04:57:30 10.1.36.1 so-0/0/3.0 Full 10.0.0.3 128 36 area 0.0.0.0, opt 0x42, DR 0.0.0.0, BDR 0.0.0.0 Up 1w2d 04:56:11, adjacent 1w2d 04:56:11
Sample Output 2
user@R1> show isis adjacency extensive R2 Interface: so-0/0/0.0, Level: 2, State: Up , Expires in 23 secs Priority: 0, Up/Down transitions: 1, Last transition: 05:57:16 ago Circuit type: 2, Speaks: IP , IPv6 Topologies: Unicast Restart capable: Yes IP addresses: 10.1.12.2 Transition log: When State Reason Fri Oct 15 14:58:35 Up Seenself R5 Interface: so-0/0/1.0, Level: 2, State: Up, Expires in 26 secs Priority: 0, Up/Down transitions: 1, Last transition: 05:56:52 ago Circuit type: 2, Speaks: IP , IPv6 Topologies: Unicast Restart capable: Yes IP addresses: 10.1.15.2 Transition log: When State Reason Fri Oct 15 14:59:00 Up Seenself R3 Interface: so-0/0/2.0, Level: 2, State: Up, Expires in 26 secs Priority: 0, Up/Down transitions: 1, Last transition: 05:56:51 ago Circuit type: 2, Speaks: IP , IPv6 Topologies: Unicast Restart capable: Yes IP addresses: 10.1.13.2 Transition log: When State Reason Fri Oct 15 14:59:01 Up Seenself user@R3> show isis adjacency extensive R4 Interface: so-0/0/0.0, Level: 2, State: Up , Expires in 25 secs Priority: 0, Up/Down transitions: 1, Last transition: 1w1d 00:22:51 ago Circuit type: 2, Speaks: IP , IPv6 Topologies: Unicast Restart capable: Yes IP addresses: 10.1.34.2 Transition log: When State Reason Thu Oct 28 15:13:12 Up Seenself R2 Interface: so-0/0/1.0, Level: 2, State: Up , Expires in 25 secs Priority: 0, Up/Down transitions: 1, Last transition: 2w2d 18:02:48 ago Circuit type: 2, Speaks: IP , IPv6 Topologies: Unicast Restart capable: Yes IP addresses: 10.1.23.1 Transition log: When State Reason Tue Oct 19 21:33:15 Up Seenself R1 Interface: so-0/0/2.0, Level: 2, State: Up , Expires in 22 secs Priority: 0, Up/Down transitions: 1, Last transition: 2w2d 17:24:06 ago Circuit type: 2, Speaks: IP , IPv6 Topologies: Unicast Restart capable: Yes IP addresses: 10.1.13.1 Transition log: When State Reason Tue Oct 19 22:11:57 Up Seenself R6 Interface: so-0/0/3.0, Level: 2, State: Up , Expires in 21 secs Priority: 0, Up/Down transitions: 1, Last transition: 2w1d 00:07:00 ago Circuit type: 2, Speaks: IP , IPv6 Topologies: Unicast Restart capable: Yes IP addresses: 10.1.36.2 Transition log: When State Reason Thu Oct 21 15:29:03 Up Seenself user@R6> show isis adjacency extensive R5 Interface: so-0/0/0.0, Level: 2, State: Up , Expires in 23 secs Priority: 0, Up/Down transitions: 1, Last transition: 1w2d 01:10:03 ago Circuit type: 2, Speaks: IP , IPv6 Topologies: Unicast Restart capable: Yes IP addresses: 10.1.56.1 Transition log: When State Reason Wed Oct 27 14:35:32 Up Seenself R4 Interface: so-0/0/1.0, Level: 2, State: Up , Expires in 25 secs Priority: 0, Up/Down transitions: 1, Last transition: 1w1d 00:26:50 ago Circuit type: 2, Speaks: IP , IPv6 Topologies: Unicast Restart capable: Yes IP addresses: 10.1.46.1 Transition log: When State Reason Thu Oct 28 15:18:45 Up Seenself R2 Interface: so-0/0/2.0, Level: 2, State: Up , Expires in 24 secs Priority: 0, Up/Down transitions: 1, Last transition: 2w1d 00:11:40 ago Circuit type: 2, Speaks: IP , IPv6 Topologies: Unicast Restart capable: Yes IP addresses: 10.1.26.1 Transition log: When State Reason Thu Oct 21 15:33:55 Up Seenself R3 Interface: so-0/0/3.0, Level: 2, State: Up , Expires in 19 secs Priority: 0, Up/Down transitions: 1, Last transition: 2w1d 00:11:40 ago Circuit type: 2, Speaks: IP , IPv6 Topologies: Unicast Restart capable: Yes IP addresses: 10.1.36.1 Transition log: When State Reason Thu Oct 21 15:33:55 Up Seenself
Meaning
Sample Output 1 from the ingress, transit, and egress routers shows that R1 and R3 are not established OSPF neighbors. Considering that the two interfaces so-0/0/2.0 (R1 and R3) are configured with identical IP addresses, you would expect this. The OSPF protocol routes IP packets based solely on the destination IP address contained in the IP packet header. Therefore, identical IP addresses in the autonomous system (AS) result in neighbors not establishing.
Sample Output 2 from the ingress, transit, and egress routers shows that R1 and R3 have established an IS-IS adjacency despite the identical IP addresses configured on interfaces so-0/0/2.0 on R1 and R3. The IS-IS protocol behaves differently from the OSPF protocol because it does not rely on IP to establish an adjacency. However, if the LSP is not up, it is still useful to check the IP subnet addressing in case there is a mistake in that layer. Correcting the addressing error might bring the LSP back up.
Take Appropriate Action
Problem
Depending on the error you encountered in your investigation, you must take the appropriate action to correct the problem. In this example, the IP address of an interface on transit router R2 is incorrectly configured.
Solution
To correct the error in this example, enter the following commands:
Sample Output
[edit interfaces so-0/0/2]
user@R1# show
unit 0 {
family inet {
address 10.1.13.2/30; <<< Incorrect IP address
}
family iso;
family mpls;
}
[edit interfaces so-0/0/2]
user@R1# rename unit 0 family inet address 10.1.13.2/30 to address 10.1.13.1/30
[edit interfaces so-0/0/2]
user@R1# show
unit 0 {
family inet {
address 10.1.13.1/30; <<< Correct IP address.
}
family iso;
family mpls;
}
[edit interfaces so-0/0/2]
user@R1# commit
commit complete
Meaning
The sample output shows that interface so-0/0/2 on ingress router R1 is now configured with the correct IP address. This correction results in unique subnet IP addresses for all interfaces in the MPLS network in MPLS Network Broken at the IP and IGP Layers, and the possibility that the LSP might come up.
Verify the LSP Again
Purpose
After taking the appropriate action to correct the error, the LSP needs to be checked again to confirm that the problem in the OSPF protocol has been resolved.
Action
To verify the LSP again, enter the following command on the ingress, transit, and egress routers:
Sample Output 1
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
Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 20)
10.1.13.2 S 10.1.36.2 S
Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt):
10.1.13.2 10.1.36.2
54 Oct 15 21:28:16 Selected as active path
53 Oct 15 21:28:16 Record Route: 10.1.13.2 10.1.36.2
52 Oct 15 21:28:16 Up
51 Oct 15 21:28:16 10.1.15.1: MPLS label allocation failure[2 times]
50 Oct 15 21:28:11 CSPF: computation result accepted
49 Oct 15 21:27:42 10.1.15.1: MPLS label allocation failure
48 Oct 15 21:27:42 CSPF: computation result accepted
47 Oct 15 21:27:31 10.1.15.1: MPLS label allocation failure[4 times]
46 Oct 15 21:27:13 Originate Call
45 Oct 15 21:27:13 CSPF: computation result accepted
[...Output truncated...]
Created: Thu Oct 14 16:04:34 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: 149, Since: Fri Oct 15 21:28:13 2004
Tspec: rate 0bps size 0bps peak Infbps m 20 M 1500
Port number: sender 13 receiver 39024 protocol 0
PATH rcvfrom: 10.1.13.2 (so-0/0/2.0) 10 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
Sample Output 2
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: 100336, Label out: 3 Time left: 156, Since: Fri Oct 15 21:15:47 2004 Tspec: rate 0bps size 0bps peak Infbps m 20 M 1500 Port number: sender 13 receiver 39024 protocol 0 PATH rcvfrom: 10.1.36.2 (so-0/0/3.0) 11 pkts Adspec: received MTU 1500 sent MTU 1500 PATH sentto: 10.1.13.1 (so-0/0/2.0) 11 pkts RESV rcvfrom: 10.1.13.1 (so-0/0/2.0) 11 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: 100352, Label out: 3 Time left: 159, Since: Fri Oct 15 21:15:50 2004 Tspec: rate 0bps size 0bps peak Infbps m 20 M 1500 Port number: sender 5 receiver 47901 protocol 0 PATH rcvfrom: 10.1.13.1 (so-0/0/2.0) 11 pkts Adspec: received MTU 1500 sent MTU 1500 PATH sentto: 10.1.36.2 (so-0/0/3.0) 11 pkts RESV rcvfrom: 10.1.36.2 (so-0/0/3.0) 11 pkts Explct route: 10.1.36.2 Record route: 10.1.13.1 <self> 10.1.36.2 Total 2 displayed, Up 2 , Down 0
Sample Output 3
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
187 Oct 15 21:20:05 Selected as active path
186 Oct 15 21:20:05 Record Route: 10.1.36.1 10.1.13.1
185 Oct 15 21:20:05 Up
184 Oct 15 21:20:05 Clear Call
183 Oct 15 21:20:05 CSPF: computation result accepted
182 Oct 15 21:20:05 CSPF: link down/deleted 10.1.13.2(R3.00/10.0.0.3)->10.1.13.2(R1.00/10.0.0.1)
[...Output truncated...]
Created: Tue Aug 17 12:18:33 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: 144, Since: Fri Oct 15 21:20:08 2004
Tspec: rate 0bps size 0bps peak Infbps m 20 M 1500
Port number: sender 5 receiver 47901 protocol 0
PATH rcvfrom: 10.1.36.1 (so-0/0/3.0) 11 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
Meaning
Sample Output 1 from ingress router R1 shows that LSP R1-to-R6 has an active route to R6 and the state is up. The output shows that the egress LSP session R6-to-R1 received and sent a recovery label.
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.
