[j-nsp] "set routing-options protect core" breaks local-preference
Rob Foehl
rwf at loonybin.net
Wed Sep 26 18:20:00 EDT 2018
On Mon, 10 Sep 2018, Ivan Malyarchuk wrote:
> Hi. We also find something wrong with "protect core".
> Seems like Junos 18.1 and 18.2 (running on MX204 in our case) makes one #Multipath equal-cost group with ALL paths except one worst AND one with worst path - as backup.
>
> I think it must create #Multipath forwarding-only route with one best (active, with weight of nexthop 0x1, find in detail output) and one "second best" path as backup (with weight 0x4000). However I cant find any public PR or Known Issues references in 18.x release notes nor in prsearch.
Just hit this issue with 17.4R2 on a newly installed RE-S-X6-64G. PIC
works fine as long as all routes are equivalent local preference; as soon
as one arrives with a lower preference, the #Multipath entry appears with
all higher preference routes installed as equivalent active routes and the
lower preference as the sole inactive:
#Multipath Preference: 255
[...]
Protocol next hop: [X]
Indirect next hop: 0x940dc00 1048575 INH Session ID: 0x143 Weight 0x1
Protocol next hop: [Y]
Indirect next hop: 0x940da00 1048574 INH Session ID: 0x142 Weight 0x1
Protocol next hop: [Z]
Indirect next hop: 0x9411800 1048624 INH Session ID: 0x161 Weight 0x4000
State: <ForwardingOnly Int Ext>
Inactive reason: Forwarding use only
In this case, [X] has a greater IGP cost than [Y], and the BGP decision
is correct, but [X] is still installed in the forwarding table as an
active route.
Anyone have any PRs or existing tickets they'd be willing to share
(off-list is fine) for purposes of sending JTAC in the right direction?
-Rob
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