Routing

Hello,

We have a multihomed bgp environment, I wan't to create additional routing instance which will be using cheep links with expensive ones acting as a backup.

http://www.gossamer-threads.com/lists/nsp/juniper/3483 provides almost good solution for us, but we also have backup links we want to use only as the last resort when all other links fail including expensive ones.

Is it now possible to alter metrics while importing routes to rib ?

Thanks, Michal Grzedzicki

Hello,

Yes, you can manipulate BGP attributes with rib-group import policy.

i managed to get it working, but I have few more questions

my config looks like this

routing-options {
    interface-routes {
        rib-group inet test;
    }
    rib-groups {
        test {
            import-rib [ inet.0 test.inet.0 ];
            import-policy test_import;
        }
    }                                   
}
protocols {
    bgp {
        local-as 65555;
        group test {
            import inet_import;
            family inet {
                unicast {
                    rib-group test;
                }
            }
            peer-as 65554;
            neighbor x.x.x.x;
        }
}

policy-options {
    policy-statement test_import {
        term test {
            from {
                neighbor x.x.x.x;
            }
            then {
                local-preference add 100;
                accept;
            }
        }
        term accept {
            then accept;
        }
    }
    policy-statement inet_import {
        term accept {
            then {
                local-preference add 20;
                accept;
            }
        }
    }
}
routing-instances {
    test {
        instance-type forwarding;
    }
}

routes in test.inet.0 have local preference of 240

192.168.6.0/24     *[BGP/170] 00:11:01, MED 0, localpref 240

in inet.0

192.168.6.0/24     *[BGP/170] 00:11:40, MED 0, localpref 120

this looks like inet_import was applied twice for test.inet.0, why ?

Is

routing-instances {
    test {
        instance-type forwarding;
    }
}

right for this scenario ? (multiple bgp feeds, I want to send some selected traffic using alternative cheeper links)

How much memory will it cost us?

Currently we use

> show chassis routing-engine 
Routing Engine status:
    Temperature                 40 degrees C / 104 degrees F
    CPU temperature             52 degrees C / 125 degrees F
    DRAM                      2048 MB
    Memory utilization          43 percent

> show chassis fpc               
                     Temp  CPU Utilization (%)   Memory    Utilization (%)
Slot State            (C)  Total  Interrupt      DRAM (MB) Heap     Buffer
  0  Online            38      6          0       1024       32         13
  1  Online            38      6          0       1024       32         13

--

Michal Grzedzicki

By default the "local-preference" is equal to 100.

"inet_import" add another 20 to the imported routes ie you get 120, at the rib-group level you add another 100 ie you get 220.

Using rib-group to import bgp feed will increase the memory  usage because you keep the same prefix in two different routing and forwarding tables.

but I'm getting 240 in test.inet.0 not 220

how much more memory will it use ? 100% more 50% more ?

--

Michal Grzedzicki