Hi,
I discussed with a colleague this afternoon and we have finally find a way to make it work.
BGP session between PE1 and PE2 has been disabled.
The following configuration been applied on PE1
set policy-options policy-statement EGRESS_LDP term EXPORT from protocol direct
set policy-options policy-statement EGRESS_LDP term EXPORT then accept
set protocols ldp egress-policy EGRESS_LDP
The interface GE-0/0/0 is advertised in the IGP (my case ISIS) as passive interface
on PE2 I did similar but instead list individual interface I decide to use sentence "from protocol direct"
again the interface ge-0/0/1 is advertized in the IGP as passive interface (since no neighbor is present)
This makes prefix 192.168.200.0/30 be advertised with label to PE2 by PE1, and prefixe 192.168.3.0/30 is now advertized to PE1 with label by PE2. To see the difference the BGP session between router has to be disabled.
This makes 192.168.200.1 be reachable from PE2 using labels. But it not enough to make network present on CE1 be reachable. The reverse is also true 192.168.3.1 is reachable from PE1 using label but network on CE2 aren't.
Now what would be interesting use case for this ?
The route with label is present in routing table
jcluser@PE1# run show route 192.168.3.0/30 extensive
inet.0: 20 destinations, 20 routes (20 active, 0 holddown, 0 hidden)
192.168.3.0/30 (1 entry, 1 announced)
State: <FlashAll>
TSI:
KRT in-kernel 192.168.3.0/30 -> {192.168.211.1}
*IS-IS Preference: 18
Level: 2
Next hop type: Router, Next hop index: 615
Address: 0xc4b8c84
Next-hop reference count: 8
Next hop: 192.168.211.1 via ge-0/0/1.0, selected
Session Id: 0x141
State: <Active Int>
Local AS: 65500
Age: 21:36 Metric: 30
Validation State: unverified
ORR Generation-ID: 0
Task: IS-IS
Announcement bits (2): 0-KRT 6-LDP
AS path: I
Thread: junos-main
inet.3: 3 destinations, 3 routes (3 active, 0 holddown, 0 hidden)
192.168.3.0/30 (1 entry, 1 announced)
State: <FlashAll>
*LDP Preference: 9
Next hop type: Router, Next hop index: 0
Address: 0xc4b8e8c
Next-hop reference count: 2
Next hop: 192.168.211.1 via ge-0/0/1.0, selected
Label operation: Push 299904
Label TTL action: prop-ttl
Load balance label: Label 299904: None;
Label element ptr: 0xcbc5b10
Label parent element ptr: 0x0
Label element references: 1
Label element child references: 0
Label element lsp id: 0
Session Id: 0x0
State: <Active Int>
Local AS: 65500
Age: 21:36 Metric: 1
Validation State: unverified
Task: LDP
Announcement bits (1): 4-Resolve tree 5
AS path: I
Thread: junos-main
but the route with the label doesn't looks to be installed in the forwarding table :
jcluser@PE1# run show route forwarding-table matching 192.168.3.0/30 extensive
Routing table: default.inet [Index 0]
Internet:
Destination: 192.168.3.0/30
Route type: user
Route reference: 0 Route interface-index: 0
Multicast RPF nh index: 0
P2mpidx: 0
Flags: sent to PFE, rt nh decoupled
Nexthop: 192.168.211.1
Next-hop type: unicast Index: 615 Reference: 11
Next-hop interface: ge-0/0/1.0
Routing table: __pfe_private__.inet [Index 3]
Internet:
Routing table: __juniper_services__.inet [Index 5]
Internet:
Routing table: __master.anon__.inet [Index 6]
Internet:
I undersatand that it can be useful when 2 router can't have BGP session be established for some reason, but if I have to set static route to make network be reachable over this MPLS session I'm questionning the benefit at the end. May for Carier over Carier topology ?
attached to this new post the 2 new routers configurations.
Thank you
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Xine
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Original Message:
Sent: 02-21-2024 22:36
From: xine32
Subject: LDP MPLS Policy export not working as expected
Hi,
I'm currenly studdying for the JNCIS-SP exam. I'm using Juniper V-LAB to test my knowledge. For this lab I used the topology named "Intra-AS BGP-CT" which is preety simple 5 VMX router connected in one line to each others.
I have attached to this post my own topology and router configuration. I start each lab session by erasing the current router configuration and paste mine to do my lab session.
I have configured on PE1 a policy export to reinsert the network 192.168.200.0/30 in the MPLS topology. But it doesn't seem to work as I expect. Using "show route 192.168.200.0/30 advertising-protocol bgp 192.168.2.4 " is currently provide no output. On PE2 I don't get any route for 192.168.200.0/30 as I expect.
I also include the traceoption output for flag "route, address & policy" been set.
Thank you
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Xine
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