12-08-2019 05:06 AM
Trying to learn Segment routing :)
I am trying to setup a SRTE ODN scenario as per the following topology
Currently
Here are the CLI output to present the scenario
No route to remote AGG (10.10.10.10) from local AGG (10.9.9.9)
RP/0/0/CPU0:AGG01#show route ipv4 unicast 10.10.10.10 Sun Dec 8 11:28:58.623 UTC % Network not in table
VPNV4 routes are received by AGG with next-hop unchanged
RP/0/0/CPU0:AGG01#show bgp vrf A | be Network Sun Dec 8 11:29:41.690 UTC Network Next Hop Metric LocPrf Weight Path Route Distinguisher: 100:1 (default for vrf A) *> 20.1.0.0/30 0.0.0.0 0 32768 ? * 20.1.0.2 0 0 200 ? *> 20.1.100.0/24 20.1.0.2 0 0 200 ? *> 20.1.101.0/24 20.1.0.2 0 0 200 ? * i20.3.0.0/30 10.10.10.10 C:111 0 100 0 ? * i20.3.100.0/24 10.10.10.10 C:111 0 100 0 200 ? * i20.3.101.0/24 10.10.10.10 C:111 0 100 0 200 ? Processed 6 prefixes, 7 path
SRTE ODN tunnel is triggered
RP/0/0/CPU0:AGG01#show bgp vrf A 20.3.100.0/24 Sun Dec 8 11:30:50.625 UTC BGP routing table entry for 20.3.100.0/24, Route Distinguisher: 100:1 Versions: Process bRIB/RIB SendTblVer Speaker 78 78 Last Modified: Dec 8 08:44:13.324 for 02:46:37 Paths: (1 available, no best path) Not advertised to any peer Path #1: Received by speaker 0 Not advertised to any peer 200 10.10.10.10 C:111 (bsid:24012) (inaccessible) from 10.5.5.5 (10.10.10.10) Received Label 24007 Origin incomplete, metric 0, localpref 100, valid, internal, import-candidate, imported Received Path ID 0, Local Path ID 0, version 0 Extended community: Color:111 RT:100:1 Originator: 10.10.10.10, Cluster list: 10.5.5.5, 10.11.11.11, 10.7.7.7 SR policy color 111, up, registered, bsid 24012, if-handle 0x00000070 Source AFI: VPNv4 Unicast, Source VRF: A, Source Route Distinguisher: 100:1 RP/0/0/CPU0:AGG01# RP/0/0/CPU0:AGG01#show mpls forwarding labels 24012 detail Sun Dec 8 11:31:56.891 UTC Local Outgoing Prefix Outgoing Next Hop Bytes Label Label or ID Interface Switched ------ ----------- ------------------ ------------ --------------- ------------ 24012 Pop No ID srte_c_111_e point2point 0 Updated: Dec 6 16:07:23.276 Version: 25, Priority: 2 Label Stack (Top -> Bottom): { Unlabelled Imp-Null } NHID: 0x0, Encap-ID: N/A, Path idx: 0, Backup path idx: 0, Weight: 0 MAC/Encaps: 0/0, MTU: 0 Outgoing Interface: srte_c_111_ep_10.10.10.10 (ifhandle 0x00000070) Packets Switched: 0 RP/0/0/CPU0:AGG01#
SRTE policy status
RP/0/0/CPU0:AGG01#show segment-routing traffic-eng policy color 111 Sun Dec 8 11:33:00.136 UTC SR-TE policy database --------------------- Color: 111, End-point: 10.10.10.10 Name: srte_c_111_ep_10.10.10.10 Status: Admin: up Operational: up for 1d19h (since Dec 6 16:07:23.276) Candidate-paths: Preference: 200 (BGP ODN) (shutdown) Requested BSID: dynamic Dynamic (invalid) Preference: 100 (BGP ODN) (active) Requested BSID: dynamic PCC info: Symbolic name: bgp_c_111_ep_10.10.10.10_discr_100 PLSP-ID: 1 Dynamic (pce 10.12.12.12) (valid) Metric Type: IGP, Path Accumulated Metric: 5 16005 [Prefix-SID, 10.5.5.5] 16007 [Prefix-SID, 10.7.7.7] 16010 [Prefix-SID, 10.10.10.10] Attributes: Binding SID: 24012 Forward Class: 0 Steering BGP disabled: no IPv6 caps enable: yes
CEF entry
RP/0/0/CPU0:AGG01#show cef vrf A 20.3.100.1 Sun Dec 8 11:33:45.393 UTC 0.0.0.0/0, version 0, proxy default, default route handler, drop adjacency, internal 0x1001011 0x0 (ptr 0xa14153c4) [1], 0x0 (0xa13f8238), 0x0 (0x0) Updated Dec 6 16:00:02.726 Prefix Len 0, traffic index 0, precedence n/a, priority 15 via 0.0.0.0/32, 7 dependencies, weight 0, class 0 [flags 0x0] path-idx 0 NHID 0x0 [0xa0ee2148 0x0] next hop 0.0.0.0/32 drop adjacency RP/0/0/CPU0:AGG01#
I have achieved that by doing the following .........
RP/0/0/CPU0:AGG01(config-static)#address-family ipv4 unicast RP/0/0/CPU0:AGG01(config-static-afi)#0.0.0.0/1 null 0 RP/0/0/CPU0:AGG01(config-static-afi)#commit
Results:
RP/0/0/CPU0:AGG01#show bgp vrf A | be Network Sun Dec 8 11:35:56.974 UTC Network Next Hop Metric LocPrf Weight Path Route Distinguisher: 100:1 (default for vrf A) *> 20.1.0.0/30 0.0.0.0 0 32768 ? * 20.1.0.2 0 0 200 ? *> 20.1.100.0/24 20.1.0.2 0 0 200 ? *> 20.1.101.0/24 20.1.0.2 0 0 200 ? *>i20.3.0.0/30 10.10.10.10 C:111 0 100 0 ? *>i20.3.100.0/24 10.10.10.10 C:111 0 100 0 200 ? *>i20.3.101.0/24 10.10.10.10 C:111 0 100 0 200 ? Processed 6 prefixes, 7 paths RP/0/0/CPU0:AGG01# RP/0/0/CPU0:AGG01#show cef vrf A 20.3.100.1 detail Sun Dec 8 11:36:52.720 UTC 20.3.100.0/24, version 33, internal 0x5000001 0x0 (ptr 0xa1416c60) [1], 0x0 (0x0), 0x208 (0xa1757554) Updated Dec 8 11:35:13.736 Prefix Len 24, traffic index 0, precedence n/a, priority 3 gateway array (0xa1350128) reference count 3, flags 0x2038, source rib (7), 0 backups [1 type 1 flags 0x48441 (0xa1773718) ext 0x0 (0x0)] LW-LDI[type=0, refc=0, ptr=0x0, sh-ldi=0x0] gateway array update type-time 1 Dec 8 11:35:13.736 LDI Update time Dec 8 11:35:13.736 via local-label 24012, 3 dependencies, recursive [flags 0x6000] path-idx 0 NHID 0x0 [0xa17cbfcc 0x0] recursion-via-label next hop VRF - 'default', table - 0xe0000000 next hop via 24012/0/21 next hop srte_c_111_e labels imposed {ImplNull 24007} Load distribution: 0 (refcount 1) Hash OK Interface Address 0 Y recursive 24012/0 RP/0/0/CPU0:AGG01#
IOS Version:
RP/0/0/CPU0:AGG01#show ver brief | in VersSun Dec 8 11:24:46.940 UTC Cisco IOS XR Software, Version 6.6.2[Default] ROM: GRUB, Version 1.99(0), DEV RELEASE
Thanks in advance for support me to learn
01-21-2020 08:04 AM
@samarjit dutta hello,
yes, indeed, for SR ODN to work, the less specific length for next-hop resolution is >= 1.
Default route does not validate it.
This should have a meaning though, especially for BGP NLRI, to avoid next-hop resolution via default route. BGP selective next-hop address tracking has similar purpose but with increased filtering options.
Regards
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