Juniper Labs Routing eBGP (lrc,lr3)

Explanation

Here we need some details to understand the eBGP step of our multi-protocol lab.
Please check here for routing topology.

Internet Access on LR3: LR3 will use a static default route pointing to LRC.
Aggregation on LRC: LRC will aggregate all AS 65501 networks (ACX1100, LR1, LR2) into a single /22 and advertise it into AS 65502.
Next-Hop Self: We update LRC’s ibgp-export policy to set next-hop self for any external (eBGP) routes—needed if additional iBGP clients attach downstream.
OSPF Export: Finally, we export the LRC–LR3 link network into OSPF so ACX1100 learns how to reach LR3.

If everything is configured correctly:

LR3 has internet via the static route.
ACX1100 learns the aggregated /22 via eBGP→OSPF.
All nodes maintain full end-to-end connectivity and Internet access via NAT.

LRC Configuration

# 1. Update ibgp-export: set next-hop self for any external BGP routes
set policy-options policy-statement ibgp-export term nexthop from protocol bgp
set policy-options policy-statement ibgp-export term nexthop from route-type external
set policy-options policy-statement ibgp-export term nexthop then next-hop self

# 2. Aggregate AS 65501 networks into one summary route
set routing-options aggregate route 10.0.0.0/22

# 3. ebgp-export policy: send direct & aggregate networks into eBGP
set policy-options policy-statement ebgp-export term from-direct from protocol direct
set policy-options policy-statement ebgp-export term from-direct from route-filter 100.1.2.3/32 exact
set policy-options policy-statement ebgp-export term from-direct then accept
set policy-options policy-statement ebgp-export term aggregate from protocol aggregate
set policy-options policy-statement ebgp-export term aggregate then accept

# 4. Create eBGP group toward LR3
set protocols bgp group eBGP-peers type external
set protocols bgp group eBGP-peers export ebgp-export
set protocols bgp group eBGP-peers neighbor 10.0.3.1 peer-as 65502

# 5. Export the LRC–LR3 link into OSPF
set policy-options policy-statement ospf-export term from-direct from route-filter 10.0.3.0/30 exact

LR3 Configuration

# 1. Create eBGP group toward LRC
set protocols bgp local-as 65502
set protocols bgp group eBGP-peers type external
set protocols bgp group eBGP-peers neighbor 10.0.3.2 peer-as 65501
set protocols bgp group eBGP-peers export eBGP-export

# 2. Advertise LR3 loopback into eBGP
set policy-options prefix-list eBGP-export 100.3.3.3/32
set policy-options policy-statement eBGP-export term export-lo from prefix-list eBGP-export
set policy-options policy-statement eBGP-export term export-lo then accept

# 3. Add static default route via LRC
set routing-options static route 0.0.0.0/0 next-hop 10.0.3.2

Validation on LR3

1. Full Routing Table

lr3@acx1100:lr3> show route

inet.0: 11 destinations, 11 routes (11 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

0.0.0.0/0          *[Static/5] 00:34:28
                    > to 10.0.3.2 via ge-0/0/3.0
10.0.0.0/22        *[BGP/170] 00:36:49, localpref 100
                    > to 10.0.3.2 via ge-0/0/3.0
10.0.3.0/30        *[Direct/0] 2d 22:30:26
                    > via ge-0/0/3.0
10.0.4.0/30        *[Direct/0] 2d 22:30:26
                    > via ge-0/0/4.0
100.1.1.1/32       *[BGP/170] 02:24:30, localpref 100
                    > to 10.0.3.2 via ge-0/0/3.0
100.1.2.3/32       *[BGP/170] 01:33:06, localpref 100
                    > to 10.0.3.2 via ge-0/0/3.0
100.2.2.2/32       *[BGP/170] 02:24:30, localpref 100
                    > to 10.0.3.2 via ge-0/0/3.0
100.3.3.3/32       *[Direct/0] 2d 22:30:26
                    > via lo0.3

2. BGP-Only Routes

lr3@acx1100:lr3> show route protocol bgp

inet.0: 11 destinations, 11 routes (11 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

10.0.0.0/22        *[BGP/170] 00:37:33, localpref 100
                    > to 10.0.3.2 via ge-0/0/3.0
100.1.1.1/32       *[BGP/170] 02:25:14, localpref 100
                    > to 10.0.3.2 via ge-0/0/3.0
100.1.2.3/32       *[BGP/170] 01:33:50, localpref 100
                    > to 10.0.3.2 via ge-0/0/3.0
100.2.2.2/32       *[BGP/170] 02:25:14, localpref 100
                    > to 10.0.3.2 via ge-0/0/3.0

3. eBGP Neighbor Status

lr3@acx1100:lr3> show bgp neighbor 10.0.3.2
Peer: 10.0.3.2+64179 AS 65501  Local: 10.0.3.1+179 AS 65502
  Type: External    State: Established    Flags: <Sync>
  Export: [ eBGP-export ]
  Active prefixes: 4    Received prefixes: 4    Accepted prefixes: 4

4. Ping Tests

# Internet via default route
lr3@acx1100:lr3> ping count 3 8.8.8.8
64 bytes from 8.8.8.8: icmp_seq=0 ttl=57 time=2.913 ms
64 bytes from 8.8.8.8: icmp_seq=1 ttl=57 time=2.992 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=57 time=11.048 ms

# Ping ACX1100 loopback
lr3@acx1100:lr3> ping count 3 100.0.1.1
64 bytes from 100.0.1.1: icmp_seq=0 ttl=63 time=0.976 ms

# Ping LRC loopback
lr3@acx1100:lr3> ping count 3 100.1.2.3
64 bytes from 100.1.2.3: icmp_seq=0 ttl=64 time=0.969 ms

# Ping LR1 & LR2 loopbacks
lr3@acx1100:lr3> ping count 3 100.1.1.1
64 bytes from 100.1.1.1: icmp_seq=0 ttl=63 time=0.957 ms

lr3@acx1100:lr3> ping count 3 100.2.2.2
64 bytes from 100.2.2.2: icmp_seq=0 ttl=63 time=1.095 ms

5. Traceroute

lr3@acx1100:lr3> traceroute 100.2.2.2 no-resolve
 1  10.0.3.2    1.428 ms  0.885 ms  0.776 ms
 2  100.2.2.2   0.773 ms  0.812 ms  0.783 ms

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