Re: [j-nsp] Junos Load Balancing Behavior
Srx's, assuming you're running in flow mode will not load balance as of today. The forwarding table will show two routes, but it will only pick one. This has been discussed here previously, a quick google search of ECMP and SRX should help. Good luck, sorry to give you the bad news.. Tim Eberhard On Feb 2, 2012, at 11:01 AM, Devin Kennedy wrote: > Hello: > > > > I'm looking for some insight on the load balancing behavior that Junos uses > by default. We are certifying our Junos platform CE routers (SRX, MX10, > M7i) and not seeing what we expected given the documentation we have. > > > > According to the Juniper docs and the old JNCIP study guide, OSPF will > automatically load balance if there are two equal cost routes. And indeed > in the routing table we have default route advertised via OSPF to a CE > router which shows two next hops (one to each of two PE's). > > > > juniper@SRX240-5> show route 0/0 exact > > > > inet.0: 23 destinations, 23 routes (23 active, 0 holddown, 0 hidden) > > + = Active Route, - = Last Active, * = Both > > > > 0.0.0.0/0 *[OSPF/150] 20:45:21, metric 112, tag 13979 > > to 10.7.122.1 via ge-0/0/6.0 > >> to 10.7.122.2 via ge-0/0/6.0 > > > > However in the forwarding table there is only one next-hop shown and when > testing traffic flows we don't see any load balancing by default. > > > > juniper@SRX240-5> show route forwarding-table destination 0/0 > > Routing table: default.inet > > Internet: > > DestinationType RtRef Next hop Type Index NhRef Netif > > defaultuser 0ulst 262142 2 > > 80:71:1f:c0:3c:81 ucst 584 4 ge-0/0/6.0 > > defaultperm 0rjct36 4 > > 0.0.0.0/32 perm 0dscd34 2 > > > > Routing table: __master.anon__.inet > > Internet: > > DestinationType RtRef Next hop Type Index NhRef Netif > > defaultperm 0rjct 517 1 > > 0.0.0.0/32 perm 0dscd 515 1 > > > > Everything goes across the one next hop only (the one with the > in front of > it). We have to add an export policy to the routing-options > forwarding-table stanza to get it to work. > > > > This is from the Junos documentation for OSPF for version 10.4: > > > > "When several equal-cost routes to a destination exist, traffic is > distributed equally among them." > > > > http://www.juniper.net/techpubs/en_US/junos10.4/topics/concept/ospf-routing- > overview.html > > > > Shouldn't the load balancing work by default as the documentation would lead > one to believe? Does anyone have any insight into this? Is the > documentation incorrect and you actually are required to always add a > load-balancing export policy in order to get the desired load-balancing > behavior? > > > > > > > > Best Regards, > > > > Devin J Kennedy > > Juniper Engineer - AT&T Labs > > > > > > ___ > juniper-nsp mailing list juniper-nsp@puck.nether.net > https://puck.nether.net/mailman/listinfo/juniper-nsp ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] Junos Load Balancing Behavior
It's working just the like documentation says. It's per-prefix load-balancing. If you want per-flow you need to modify the FIB via an export policy. set policy-options policy-statement fib-per-flow then load-balance per-packet set routing-options forwarding-table export fib-per-flow Commit Check your FIB again after that change. Thank you, -- Doug Hanks - JNCIE-ENT #213, JNCIE-SP #875 Sr. Systems Engineer Juniper Networks On 2/2/12 9:01 AM, "Devin Kennedy" wrote: >Hello: > > > >I'm looking for some insight on the load balancing behavior that Junos >uses >by default. We are certifying our Junos platform CE routers (SRX, MX10, >M7i) and not seeing what we expected given the documentation we have. > > > >According to the Juniper docs and the old JNCIP study guide, OSPF will >automatically load balance if there are two equal cost routes. And indeed >in the routing table we have default route advertised via OSPF to a CE >router which shows two next hops (one to each of two PE's). > > > >juniper@SRX240-5> show route 0/0 exact > > > >inet.0: 23 destinations, 23 routes (23 active, 0 holddown, 0 hidden) > >+ = Active Route, - = Last Active, * = Both > > > >0.0.0.0/0 *[OSPF/150] 20:45:21, metric 112, tag 13979 > > to 10.7.122.1 via ge-0/0/6.0 > >> to 10.7.122.2 via ge-0/0/6.0 > > > >However in the forwarding table there is only one next-hop shown and when >testing traffic flows we don't see any load balancing by default. > > > >juniper@SRX240-5> show route forwarding-table destination 0/0 > >Routing table: default.inet > >Internet: > >DestinationType RtRef Next hop Type Index NhRef Netif > >defaultuser 0ulst 262142 2 > > 80:71:1f:c0:3c:81 ucst 584 4 >ge-0/0/6.0 > >defaultperm 0rjct36 4 > >0.0.0.0/32 perm 0dscd34 2 > > > >Routing table: __master.anon__.inet > >Internet: > >DestinationType RtRef Next hop Type Index NhRef Netif > >defaultperm 0rjct 517 1 > >0.0.0.0/32 perm 0dscd 515 1 > > > >Everything goes across the one next hop only (the one with the > in front >of >it). We have to add an export policy to the routing-options >forwarding-table stanza to get it to work. > > > >This is from the Junos documentation for OSPF for version 10.4: > > > >"When several equal-cost routes to a destination exist, traffic is >distributed equally among them." > > > >http://www.juniper.net/techpubs/en_US/junos10.4/topics/concept/ospf-routin >g- >overview.html > > > >Shouldn't the load balancing work by default as the documentation would >lead >one to believe? Does anyone have any insight into this? Is the >documentation incorrect and you actually are required to always add a >load-balancing export policy in order to get the desired load-balancing >behavior? > > > > > > > >Best Regards, > > > >Devin J Kennedy > >Juniper Engineer - AT&T Labs > > > > > >___ >juniper-nsp mailing list juniper-nsp@puck.nether.net >https://puck.nether.net/mailman/listinfo/juniper-nsp ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
[j-nsp] Junos Load Balancing Behavior
Hello: I'm looking for some insight on the load balancing behavior that Junos uses by default. We are certifying our Junos platform CE routers (SRX, MX10, M7i) and not seeing what we expected given the documentation we have. According to the Juniper docs and the old JNCIP study guide, OSPF will automatically load balance if there are two equal cost routes. And indeed in the routing table we have default route advertised via OSPF to a CE router which shows two next hops (one to each of two PE's). juniper@SRX240-5> show route 0/0 exact inet.0: 23 destinations, 23 routes (23 active, 0 holddown, 0 hidden) + = Active Route, - = Last Active, * = Both 0.0.0.0/0 *[OSPF/150] 20:45:21, metric 112, tag 13979 to 10.7.122.1 via ge-0/0/6.0 > to 10.7.122.2 via ge-0/0/6.0 However in the forwarding table there is only one next-hop shown and when testing traffic flows we don't see any load balancing by default. juniper@SRX240-5> show route forwarding-table destination 0/0 Routing table: default.inet Internet: DestinationType RtRef Next hop Type Index NhRef Netif defaultuser 0ulst 262142 2 80:71:1f:c0:3c:81 ucst 584 4 ge-0/0/6.0 defaultperm 0rjct36 4 0.0.0.0/32 perm 0dscd34 2 Routing table: __master.anon__.inet Internet: DestinationType RtRef Next hop Type Index NhRef Netif defaultperm 0rjct 517 1 0.0.0.0/32 perm 0dscd 515 1 Everything goes across the one next hop only (the one with the > in front of it). We have to add an export policy to the routing-options forwarding-table stanza to get it to work. This is from the Junos documentation for OSPF for version 10.4: "When several equal-cost routes to a destination exist, traffic is distributed equally among them." http://www.juniper.net/techpubs/en_US/junos10.4/topics/concept/ospf-routing- overview.html Shouldn't the load balancing work by default as the documentation would lead one to believe? Does anyone have any insight into this? Is the documentation incorrect and you actually are required to always add a load-balancing export policy in order to get the desired load-balancing behavior? Best Regards, Devin J Kennedy Juniper Engineer - AT&T Labs ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
