Routing

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  • 1.  Losing ping to neighbor loopback when I apply equal cost load balancing, why ?

    Posted 04-01-2023 20:24

    Hi, 

    I recently achieved JNCIA-JUNOS, studying for JNCIS-ENT.

    I am using vLABs to play with things and quickly ran into something I do not understand.  Attached is a photo of the topology I am messing with.  The blueprint is BGP-multi AS - but I am immediately removing BGP and OSPF protocols.   I set up static routes so I can ping the loopback of vMX2 from vMX3.  I set up IPs on ge-0/0/5

    so that I can play with equal cost multipath routing.  I can initially ping the loopback on vMX2, but once I export the policy for load balancing ping stops working.  Would someone please help me see what I am missing ?

    Here is my ping before exporting the policy.

    jcluser@vMX3> ping 192.168.2.1 rapid count 5 
    PING 192.168.2.1 (192.168.2.1): 56 data bytes
    !!!!!
    --- 192.168.2.1 ping statistics ---
    5 packets transmitted, 5 packets received, 0% packet loss
    round-trip min/avg/max/stddev = 1.002/1.274/1.461/0.151 ms

    Here is the policy:

    jcluser@vMX3> show policy balance-load 
    Policy balance-load:
        Term unnamed:
            then load-balance per-packet

    jcluser@vMX3# set export balance-load 

    [edit routing-options forwarding-table]
    jcluser@vMX3# commit and-quit 
    commit complete
    Exiting configuration mode

    ping failure after applying

    jcluser@vMX3> ping 192.168.2.1 rapid count 5 
    PING 192.168.2.1 (192.168.2.1): 56 data bytes
    .....
    --- 192.168.2.1 ping statistics ---
    5 packets transmitted, 0 packets received, 100% packet loss

    here are the changes I  load merge on the hosts to set up my environment (after deleting bpg/ospf)

    vMX2 ---

    interfaces {

        ge-0/0/5 {
            unit 0 {
                family inet {
                    address 10.100.33.1/24;
                }
            }
        }

        lo0 {
            unit 0 {
                family inet {
                    address 10.100.100.2/32;
                    address 192.168.2.1/32;
                }
            }
        }
    }
    routing-options {
        static {
            defaults {
                preference 20
            }
            route 192.168.1.1/32 next-hop [ 10.100.23.2 10.100.33.2 ];
            route 0.0.0.0/0 preference 5
        }
    }

    vMX3---
    interfaces {
        ge-0/0/5 {
            unit 0 {
                family inet {
                    address 10.100.33.2/24;
                }
            }
        }
        lo0 {
            unit 0 {
                family inet {
                    address 192.168.1.1/32
                }
            }
        }
    }
    routing-options {
        static {
            defaults {
            preference 20
            }
            route 0.0.0.0/0 preference 5
            route 192.168.2.1/32 next-hop 10.100.23.1
            route 192.168.2.1/32 next-hop 10.100.33.1
        }
    }

    Thanks for any help.  If I can  provide any more info, please let me know.

    Steve



    ------------------------------
    STEVEN STETSON
    ------------------------------


  • 2.  RE: Losing ping to neighbor loopback when I apply equal cost load balancing, why ?

     
    Posted 04-02-2023 07:45

    Looks like you are missing accept action in policy balance-load , try this command. 

    set policy-options policy-statement balance-load then accept

    Regards, 
    Nitish




  • 3.  RE: Losing ping to neighbor loopback when I apply equal cost load balancing, why ?

    Posted 04-02-2023 15:42

     policy balance-load doesn't need accept to work.

    I would bet on one link that works (and that is used when loadbalancing isn't used) and the other link that doesn't (and which becomes used only when loadbalancing is activated).



    ------------------------------
    Olivier Benghozi
    ------------------------------



  • 4.  RE: Losing ping to neighbor loopback when I apply equal cost load balancing, why ?

    Posted 04-02-2023 19:38

    Thanks Olivier.  That would make sense.  I probably have a mistake in my static routes that isn't very noticeable until traffic is forced onto one of the links.  I will try to look for that next time I start the environment.



    ------------------------------
    STEVEN STETSON
    ------------------------------



  • 5.  RE: Losing ping to neighbor loopback when I apply equal cost load balancing, why ?

    Posted 04-02-2023 15:42

    Thank you so much for the reply Nitish, but it did not correct my issue.  I am sure I am doing something silly.  I feel like I understand the main point they were making about load balancing and it is just something weird in my particular implementation causing the issue.  I will move on and assume I will gain the missing knowledge in another section.



    ------------------------------
    STEVEN STETSON
    ------------------------------