> > Unfortunately the 'show forwarding-options load-balance' doesn't allow > giving MPLS label stack to it which greatly limits utility for SP > networks.
I *think* that you can use the packet-dump option to paste a packet in hex and it will give the proper result with the label stack considered. It was a couple years ago I tried this, and my memory is fuzzy if it did work correctly or not. Even if it did work it's obvious clunky as hell to have to slap a hex decode in there. I did find a note that I asked for an ER to allow label IDs on the CLI, but I can't find anything further if they said yes/no. I'll ask. On Thu, Aug 14, 2025 at 2:26 AM Saku Ytti via NANOG <[email protected]> wrote: > Thanks Nitzan, that was what I was thinking, that is quite recent (to > me) and I suspect it is syntactical sugar for 'jsim'? > > Unfortunately the 'show forwarding-options load-balance' doesn't allow > giving MPLS label stack to it which greatly limits utility for SP > networks. > > Steinar, in your experience does the bundle-hash give correct results? > Is it actually injecting packets to ezchip/lightspeed and getting > results from the HW (cef exact-route is not doing this at least). > > Thanks to Pedro Prado for sharing that Arista has a command for this, > and indeed in Arista like in Juniper packet is actually injected to > the hardware to get the result. > > > I think none of them allow giving MPLS stack though? So mostly useful > for cloudy people, not SP people. RFC5837 would more reliably give us > the correct answer. > > On Thu, 14 Aug 2025 at 09:10, Nitzan Tzelniker via NANOG > <[email protected]> wrote: > > > > For JUNOS I think that you are looking for > > user@lab> show forwarding-options load-balance ? > > Possible completions: > > destination-address Destination IP address > > destination-port Destination port > > family Layer 3 family > > ingress-interface Ingress Logical Interface > > packet-dump Raw packet dump in hex without '0x' > > source-address Source IP address > > source-port Source port > > tos Type of Service field > > transport-protocol Transport layer protocol > > > > Nitzan > > > > On Tue, Aug 12, 2025 at 5:58 PM Saku Ytti via NANOG < > [email protected]> > > wrote: > > > > > Hey-o, > > > > > > > > > Which platform/software has a command to show which interface will be > > > used for forwarding with given keys? > > > > > > ASR9k has a cef exec-route, and I see references to this in c-nsp, > > > reddit and cisco.com forums, stressing how useful debugging tool it > > > has been. Despite it not actually working, since it's just RE > > > software, it doesn't talk to the EZchip/lightspeed, unless it has been > > > fixed in the past couple of years, certainly hasn't worked in the > > > timeline of various forums finding it useful. > > > > > > MX has 'jsim' > > > > https://www.juniper.net/documentation/en_US/day-one-books/TW_MX3D_PacketWalkthrough.pdf > > > which I think actually works, but it is quite involved. I have some > > > (false?) memory that I saw in some release note this being a bit more > > > productised into CLI command, but I'm failing to find anything to > > > support this memory. > > > > > > There is also RFC5837, which is actually implemented in QFX5k, but not > > > for TTL exceeded, we've opened ER to get it supported on MX and PTX > > > and for TTL exceeded. This RFC will allow programmatic platform > > > agnostic discovery of the actual interface used, without relying on > > > platform specific magic. So please do ask your vendors to implement > > > it. > > > > > > -- > > > ++ytti > > > _______________________________________________ > > > NANOG mailing list > > > > > > > https://lists.nanog.org/archives/list/[email protected]/message/65IZUIUM3WTM56W3CLM6HOGK2T7DCEKF/ > > > > > _______________________________________________ > > NANOG mailing list > > > https://lists.nanog.org/archives/list/[email protected]/message/HHWSKHAH2RWUUZN5XMLUCOKMCCLXCK77/ > > > > -- > ++ytti > _______________________________________________ > NANOG mailing list > > https://lists.nanog.org/archives/list/[email protected]/message/DMC65GBTZVZXSWB3NBCCOO7YRBWAXLGS/ _______________________________________________ NANOG mailing list https://lists.nanog.org/archives/list/[email protected]/message/YQQFFLNGNQUVPKOR7QCFQUSI445NO2K6/
