This stage adds RSVP-TE to SP-A in the OSPF core with the LDP links I configured in previous stages. A-PE1 sits in OSPF area 1 and A-PE2 in area 2, so every tunnel between them crosses area 0.
This is A-PE1’s Tunnel10 toward A-PE2 after it was configured during the lab:
InLabel : -
OutLabel : GigabitEthernet2, 1109
Next Hop : 10.1.1.21
RSVP Signalling Info:
Src 10.1.0.5, Dst 10.1.0.6, Tun_Id 10, Tun_Instance 616
RSVP Path Info:
My Address: 10.1.1.22
Explicit Route: 10.1.1.21 10.1.0.1 10.1.0.4*
Record Route:
Tspec: ave rate=100000 kbits, burst=1000 bytes, peak rate=100000 kbits
RSVP Resv Info:
Record Route: 10.1.0.1(1109) 10.1.1.13(1109)
10.1.0.4(1407) 10.1.1.33(1407)
10.1.0.6(3) 10.1.1.34(3)
Fspec: ave rate=100000 kbits, burst=1000 bytes, peak rate=100000 kbits
Shortest Unconstrained Path Info:
Path Weight: UNKNOWN
Explicit Route: UNKNOWNA-PE1 computed strict hops only up to A-P1 (10.1.1.21, then 10.1.0.1) and signalled A-P4’s loopback, 10.1.0.4, as a loose hop. A-P1 computed the hop to A-P4 in area 0, and A-P4 computed the hop to A-PE2 in area 2. The Resv record route lists each hop with the label it assigned: 1109 from A-P1, 1407 from A-P4 and 3 (implicit null) from A-PE2. The Shortest Unconstrained Path Info block is UNKNOWN. A-PE1 computes that path from its TE database, which holds only area 1 links; 10.1.0.6 is in area 2.
Topology file: topology.clab.yml · Addressing: ipam.md · Stage configs, 6 nodes (four P routers, two PEs): stage_configs/lab02-s1-spa-rsvp-te/
Areas and the TE Database
Area 0 holds the four P routers and every link between them, the A-P1 to A-P3 diagonal included. A-P1 and A-P2 are the ABRs for area 1, where A-PE1 sits; A-P3 and A-P4 are the ABRs for area 2, with A-PE2.
OSPF carries the TE attributes of each link in Type-10 opaque LSAs, and a Type-10 LSA is flooded only inside its own area. Each ABR runs TE in both of its areas. On A-P1:
mpls traffic-eng tunnels
!
router ospf 1
mpls traffic-eng router-id Loopback0
mpls traffic-eng area 0
mpls traffic-eng area 1The full file is A-P1.ios.
A-PE1 runs TE in area 1 only and advertises two TE links there; its uplinks are to A-P1 and A-P2:
A-PE1#show ip ospf mpls traffic-eng link
OSPF Router with ID (10.1.0.5) (Process ID 1)
Area 1 has 2 MPLS TE links. Area instance is 16.
Links in hash bucket 16.
Link is associated with fragment 3. Link instance is 16
Link connected to Point-to-Point network
Link ID : 10.1.0.2
Interface Address : 10.1.1.26
Neighbor Address : 10.1.1.25
Admin Metric te: 1 igp: 1
Maximum bandwidth : 125000000
Maximum reservable bandwidth : 125000000
Number of Priority : 8
Priority 0 : 125000000 Priority 1 : 125000000
Priority 2 : 125000000 Priority 3 : 125000000
Priority 4 : 125000000 Priority 5 : 125000000
Priority 6 : 125000000 Priority 7 : 125000000
Affinity Bit : 0x0
Links in hash bucket 48.
Link is associated with fragment 2. Link instance is 16
Link connected to Point-to-Point network
Link ID : 10.1.0.1
Interface Address : 10.1.1.22
Neighbor Address : 10.1.1.21
Admin Metric te: 1 igp: 1
Maximum bandwidth : 125000000
Maximum reservable bandwidth : 125000000
Number of Priority : 8
Priority 0 : 125000000 Priority 1 : 125000000
Priority 2 : 125000000 Priority 3 : 125000000
Priority 4 : 125000000 Priority 5 : 125000000
Priority 6 : 125000000 Priority 7 : 106250000
Affinity Bit : 0x0Area 1 has no other links. For A-PE1, A-PE2’s loopback is an inter-area route from a Type-3 summary LSA, so CSPF on A-PE1 has no path to 10.1.0.6.
Loose-Hop Explicit Paths
IOS-XE does not support a dynamic path option, autoroute announce or affinity on an inter-area tunnel. The explicit path has to name the ABRs: the headend computes the path to the first ABR, and each ABR computes the next part inside its own area, up to the next loose hop.
Tunnel10 has three path options: NORTH through A-P1 and A-P4, SOUTH through the other ABR pair, A-P2 and A-P3, and a last option that names only the destination, 10.1.0.6:
ip explicit-path name NORTH-PE1-PE2
next-address loose 10.1.0.1
next-address loose 10.1.0.4
ip explicit-path name SOUTH-PE1-PE2
next-address loose 10.1.0.2
next-address loose 10.1.0.3
!
interface Tunnel10
description TE to A-PE2 : NORTH primary / SOUTH secondary
ip unnumbered Loopback0
tunnel mode mpls traffic-eng
tunnel destination 10.1.0.6
tunnel mpls traffic-eng autoroute destination
tunnel mpls traffic-eng bandwidth 100000
tunnel mpls traffic-eng affinity 0x0 mask 0x80000000
tunnel mpls traffic-eng path-option 10 explicit name NORTH-PE1-PE2
tunnel mpls traffic-eng path-option 20 explicit name SOUTH-PE1-PE2
tunnel mpls traffic-eng path-option 30 explicit name ANYLOOSE-PE2
tunnel mpls traffic-eng fast-reroute node-protect
!
ip explicit-path name ANYLOOSE-PE2
next-address loose 10.1.0.6The full file is A-PE1.ios.
A-PE2 has the mirror image, Tunnel20 through A-P4 and A-P1.
The affinity line is in the configuration to show how an affinity looks in the outputs. It does not change any path in this topology.
Autoroute destination
autoroute announce, unsupported on an inter-area tunnel, adds the tunnel to the headend’s SPF as a link to the tail router, so the headend has to see the tail’s TE router ID in its own area. A-PE2 advertises its TE router ID, 10.1.0.6, in area 2 only. tunnel mpls traffic-eng autoroute destination installs a static route for the tunnel destination through the tunnel instead:
A-PE1#show ip route 10.1.0.6
Routing entry for 10.1.0.6/32
Known via "static", distance 1, metric 0 (connected)
Routing Descriptor Blocks:
* directly connected, via Tunnel10
Route metric is 0, traffic share count is 1It routes only 10.1.0.6/32. That is the BGP next hop of every VPN route A-PE2 advertises, so those routes resolve through Tunnel10.
Tunnel11 on the Diagonal
Tunnel11’s explicit path names A-P1 and A-P3 as loose hops:
ip explicit-path name DIAG-PE1-PE2
next-address loose 10.1.0.1
next-address loose 10.1.0.3
!
interface Tunnel11
description TE to A-PE2 : explicit-path pinned to colored A-P1-A-P3 diagonal
ip unnumbered Loopback0
tunnel mode mpls traffic-eng
tunnel destination 10.1.0.6
tunnel mpls traffic-eng bandwidth 50000
tunnel mpls traffic-eng path-option 10 explicit name DIAG-PE1-PE2A-P1 computes the path between them. Every TE metric in area 0 is 1, so the diagonal, 10.1.1.16/30, costs 1 and the path through A-P2 or A-P4 costs 2. The Resv record route starts at 10.1.1.17, A-P1’s end of the diagonal:
A-PE1#show mpls traffic-eng tunnels tun 11
Name: TE to A-PE2 : explicit-path pinned to colored A-P1-A-P3 diagona (Tunnel11) Destination: 10.1.0.6
Status:
Admin: up Oper: up Path: valid Signalling: connected
path option 10, type explicit DIAG-PE1-PE2 (Basis for Setup, path weight 1)
Config Parameters:
Bandwidth: 50000 kbps (Global) Priority: 7 7 Affinity: 0x0/0xFFFF
Metric Type: TE (default)
Path-selection Tiebreaker:
Global: not set Tunnel Specific: not set Effective: min-fill (default)
Hop Limit: disabled
Cost Limit: disabled
Path-invalidation timeout: 10000 msec (default), Action: Tear
AutoRoute: disabled LockDown: disabled Loadshare: 50000 [40000] bw-based
auto-bw: disabled
Fault-OAM: disabled, Wrap-Protection: disabled, Wrap-Capable: No
Active Path Option Parameters:
State: explicit path option 10 is active
BandwidthOverride: disabled LockDown: disabled Verbatim: disabled
Node Hop Count: 1
InLabel : -
OutLabel : GigabitEthernet2, 1113
Next Hop : 10.1.1.21
RSVP Signalling Info:
Src 10.1.0.5, Dst 10.1.0.6, Tun_Id 11, Tun_Instance 441
RSVP Path Info:
My Address: 10.1.1.22
Explicit Route: 10.1.1.21 10.1.0.1 10.1.0.3*
Record Route:
Tspec: ave rate=50000 kbits, burst=1000 bytes, peak rate=50000 kbits
RSVP Resv Info:
Record Route: 10.1.1.17 10.1.1.29 10.1.1.30On A-P1, Gi3 has 950000 of 1000000 kbps left at priority 7, after Tunnel11’s 50 Mbps:
Link ID:: 1 (GigabitEthernet3)
Link Subnet Type: Point-to-Point
Link IP Address: 10.1.1.17
Neighbor: ID 10.1.0.3, IP 10.1.1.18
TE metric: 1
IGP metric: 1
SRLGs: None
Physical Bandwidth: 1000000 kbits/sec
Res. Global BW: 1000000 kbits/sec
Res. Sub BW: 0 kbits/sec
Downstream::
Global Pool Sub Pool
----------- ----------
Reservable Bandwidth[0]: 1000000 0 kbits/sec
Reservable Bandwidth[1]: 1000000 0 kbits/sec
Reservable Bandwidth[2]: 1000000 0 kbits/sec
Reservable Bandwidth[3]: 1000000 0 kbits/sec
Reservable Bandwidth[4]: 1000000 0 kbits/sec
Reservable Bandwidth[5]: 1000000 0 kbits/sec
Reservable Bandwidth[6]: 1000000 0 kbits/sec
Reservable Bandwidth[7]: 950000 0 kbits/sec
Attribute Flags: 0x80000000A-PE2’s Tunnel21 takes the diagonal in the other direction, from A-P3’s end.
The diagonal carries bit 31: mpls traffic-eng attribute-flags 0x80000000 on A-P1 Gi3 and A-P3 Gi2, the Attribute Flags line in the A-P1 output. An affinity of 0x80000000 mask 0x80000000 on Tunnel11 would require bit 31 on every link of the path, A-PE1’s own first hop included. Both of A-PE1’s area-1 uplinks advertise Affinity Bit : 0x0 in its show ip ospf mpls traffic-eng link output, so CSPF on A-PE1 finds no path. Tunnel11 uses an explicit path instead.
FRR at A-P1
A-P1 protects the NORTH path’s area-0 hop, A-P1 to A-P4 over Gi4, with two backup tunnels. Tunnel100 is the next-hop (NHOP) backup for the link: a strict path through A-P3 to A-P4, all inside area 0. Tunnel101 is the next-next-hop (NNHOP) backup for the node A-P4: loose through A-P3 to A-PE2, so it ends in area 2 and is an inter-area tunnel itself. Both are bound to Gi4:
ip explicit-path name BKP-LINK-P1P3P4
next-address 10.1.0.3
next-address 10.1.0.4
!
interface Tunnel100
description FRR NHOP link-protect -> A-P4
ip unnumbered Loopback0
tunnel mode mpls traffic-eng
tunnel destination 10.1.0.4
tunnel mpls traffic-eng path-option 10 explicit name BKP-LINK-P1P3P4
!
ip explicit-path name BKP-NODE-VIA-P3
next-address loose 10.1.0.3
next-address loose 10.1.0.6
!
interface Tunnel101
description FRR NNHOP node-protect -> A-PE2 (inter-area)
ip unnumbered Loopback0
tunnel mode mpls traffic-eng
tunnel destination 10.1.0.6
tunnel mpls traffic-eng path-option 10 explicit name BKP-NODE-VIA-P3
!
interface GigabitEthernet4
mpls traffic-eng backup-path Tunnel100
mpls traffic-eng backup-path Tunnel101
Neither backup has a backup-bw line, which leaves them at “any pool unlimited”: they protect an LSP from any bandwidth pool, with no bandwidth guarantee:
A-P1#show mpls traffic-eng tunnels backup
FRR NHOP link-protect -> A-P4
LSP Head, Admin: up, Oper: up
Tun ID: 100, LSP ID: 53, Source: 10.1.0.1
Destination: 10.1.0.4
Fast Reroute Backup Provided:
Protected i/fs: Gi4
Protected LSPs/Sub-LSPs: 0, Active: 0
Backup BW: any pool unlimited; inuse: 0 kbps
Backup flags: 0x0
FRR NNHOP node-protect -> A-PE2 (inter-area)
LSP Head, Admin: up, Oper: up
Tun ID: 101, LSP ID: 41, Source: 10.1.0.1
Destination: 10.1.0.6
Fast Reroute Backup Provided:
Protected i/fs: Gi4
Protected LSPs/Sub-LSPs: 1, Active: 0
Backup BW: any pool unlimited; inuse: 100000 kbps
Backup flags: 0x0Tunnel10’s configuration carries fast-reroute node-protect. In the FRR database, A-P1 protects 10.1.0.5 10 [616], Tunnel10’s LSP from A-PE1, with Tunnel101, the NNHOP backup. Tunnel101’s label is implicit null. The merge point, A-PE2, is also the tail, and it signalled label 3 (10.1.0.6(3) in the opening capture):
A-P1#show mpls traffic-eng fast-reroute database
P2P Headend FRR information:
Protected tunnel In-label Out intf/label FRR intf/label Status
--------------------------- -------- -------------- -------------- ------
P2P LSP midpoint frr information:
LSP identifier In-label Out intf/label FRR intf/label Status
--------------------------- -------- -------------- -------------- ------
10.1.0.5 10 [616] 1109 Gi4:1407 Tu101:implicit-n readyFailover and Restore
I shut A-P1’s Gi4. A-P1 switched LSP 616 to Tunnel101:
A-P1#show mpls traffic-eng fast-reroute database detail
FRR Database Summary:
Protected interfaces : 1
Protected LSPs/Sub-LSPs : 1
Backup tunnels : 2
Active interfaces : 1
FRR Active tunnels : 1
P2P LSPs:
Tun ID: 10, LSP ID: 616, Source: 10.1.0.5
Destination: 10.1.0.6
State : active
InLabel : 1109
OutLabel : Gi4:1407
FRR OutLabel : Tu101:implicit-null
P2MP Sub-LSPs:A-P1 then sent A-PE1 a PathErr, Notify: Tunnel locally repaired, and A-PE1 moved Tunnel10 to path option 20, SOUTH, as LSP 638 through A-P2 and A-P3:
A-PE1#show mpls traffic-eng tunn tun 10
Name: TE to A-PE2: NORTH primary / SOUTH secondary (Tunnel10) Destination: 10.1.0.6
Status:
Admin: up Oper: up Path: valid Signalling: connected
path option 20, type explicit SOUTH-PE1-PE2 (Basis for Setup, path weight 1)
path option 10, type explicit NORTH-PE1-PE2
path option 30, type explicit ANYLOOSE-PE2
Config Parameters:
Bandwidth: 100000 kbps (Global) Priority: 7 7 Affinity: 0x0/0x80000000
Metric Type: TE (default)
Path-selection Tiebreaker:
Global: not set Tunnel Specific: not set Effective: min-fill (default)
Hop Limit: disabled
Cost Limit: disabled
Path-invalidation timeout: 10000 msec (default), Action: Tear
AutoRoute: disabled LockDown: disabled Loadshare: 100000 [20000] bw-based
AutoRoute destination: enabled
auto-bw: disabled
Fast Reroute: enabled, Node Protection: Yes, Bandwidth Protection: No
Fault-OAM: disabled, Wrap-Protection: disabled, Wrap-Capable: No
Active Path Option Parameters:
State: explicit path option 20 is active
BandwidthOverride: disabled LockDown: disabled Verbatim: disabled
Node Hop Count: 1
InLabel : -
OutLabel : GigabitEthernet3, 1207
Next Hop : 10.1.1.25
RSVP Signalling Info:
Src 10.1.0.5, Dst 10.1.0.6, Tun_Id 10, Tun_Instance 638
RSVP Path Info:
My Address: 10.1.1.26
Explicit Route: 10.1.1.25 10.1.0.2 10.1.0.3*
Record Route:
Tspec: ave rate=100000 kbits, burst=1000 bytes, peak rate=100000 kbits
RSVP Resv Info:
Record Route: 10.1.0.2(1207) 10.1.1.5(1207)
10.1.0.3(1308) 10.1.1.29(1308)
10.1.0.6(3) 10.1.1.30(3)
Fspec: ave rate=100000 kbits, burst=1000 bytes, peak rate=100000 kbits
Shortest Unconstrained Path Info:
Path Weight: UNKNOWN
Explicit Route: UNKNOWN
History:
Tunnel:
Time since created: 22 hours, 27 minutes
Time since path change: 1 minutes, 3 seconds
Number of LSP IDs (Tun_Instances) used: 638
Current LSP: [ID: 638]
Uptime: 1 minutes, 6 seconds
Selection: reoptimization
Prior LSP: [ID: 616]
ID: path option 10 [616]
Removal Trigger: re-route path error
Last Error: RSVP:: Path Error from 10.1.1.21: Notify: Tunnel locally repaired (flags 0)
A-PE1#show ip route 10.1.0.6
Routing entry for 10.1.0.6/32
Known via "static", distance 1, metric 0 (connected)
Routing Descriptor Blocks:
* directly connected, via Tunnel10
Route metric is 0, traffic share count is 1The route that autoroute destination installed is tied to the Tunnel10 interface, so it did not change when the path under it did.
After no shutdown on Gi4 and a reoptimization on A-PE1, Tunnel10 went back to NORTH as LSP 639, with A-P1’s new label 1112:
OutLabel : GigabitEthernet2, 1112
Next Hop : 10.1.1.21
RSVP Signalling Info:
Src 10.1.0.5, Dst 10.1.0.6, Tun_Id 10, Tun_Instance 639On A-P1, Tunnel101 protects the new LSP again, and A-P4’s label for it is 1409:
P2P LSP midpoint frr information:
LSP identifier In-label Out intf/label FRR intf/label Status
--------------------------- -------- -------------- -------------- ------
10.1.0.5 10 [639] 1112 Gi4:1409 Tu101:implicit-n readyWhat’s Next
Adding RSVP-TE didn’t reset LDP on the same links. A-PE1’s two LDP sessions show 7w4d of uptime:
A-PE1#show mpls ldp neigh | i Up
Up time: 7w4d
Up time: 7w4dThe next stage adds SR-MPLS to three SP-A nodes and connects it to the LDP-only part of the network.
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