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Fix: Mark phantom links used to create multihop EBGP sessions #2502

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Merged
ipspace merged 3 commits into from
Jul 9, 2025
Merged

Fix: Mark phantom links used to create multihop EBGP sessions #2502

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e681131
Fix: Mark phantom links used to create multihop EBGP sessions
ipspace Jul 8, 2025
7747e95
Cleanup the ebgp.multihop module based on review comments
ipspace Jul 9, 2025
68f7a3f
Fix: different linkindex values have to be used on phantom links
ipspace Jul 9, 2025
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1 change: 1 addition & 0 deletions netsim/extra/ebgp.multihop/plugin.py
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Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,7 @@ def pre_link_transform(topology: Box) -> None:
if 'vrf' in intf:
intf.bgp._vrf = intf.vrf
intf._bgp_session = True
intf._phantom_link = True
intf.ifname = f'_ebgp_multihop_{s.linkindex}'

topology.links.extend(sessions)
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2 changes: 2 additions & 0 deletions netsim/modules/routing.py
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Expand Up @@ -829,6 +829,8 @@ def resolve_node_nexthop(sr_data: Box, node: Box, topology: Box) -> Box:

node_found = False
for intf in node.interfaces:
if intf.get('_phantom_link',False):
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@jbemmel jbemmel Jul 8, 2025

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Why not simply check for _bgp_session here? It implies "phantom_link"

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@ipspace ipspace Jul 8, 2025

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... because I'd like to have a generic mechanism we might need in the future (one of these days we'll tackle TE, and the TE tunnels might be another case of phantom links).

continue
for ngb in intf.neighbors:
if ngb.node != sr_data.nexthop.node:
continue
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2 changes: 2 additions & 0 deletions tests/topology/expected/ebgp.utils.yml
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Expand Up @@ -13,6 +13,7 @@ bgp:
password: Funny
interfaces:
- _bgp_session: true
_phantom_link: true
bgp:
local_as: 123
multihop: 255
Expand All @@ -21,6 +22,7 @@ bgp:
ipv4: 10.0.0.2/32
node: r2
- _bgp_session: true
_phantom_link: true
bgp:
local_as: 456
multihop: 255
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