Routing

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  • 1.  Default route question/issue

     
    Posted 12-31-2021 14:43
    With regard to 'routing-options' on an SRX device I believe I cannot  specify a physical interface as a hop under 'static' > 'route 0.0.0.0/0', is this correct? The interface in question carries a DHCP assigned address, and this cannot be changed to a static. If I am correct, how can I get around this please?

    i.e. 

    routing-options {
        static {
            route 0.0.0.0/0 {
                next-hop #.#.#.#;
                qualified-next-hop ge-0/0/7.0 {
                    preference 25;
                }
            }
        }
        router-id #.#.#.#;
    }​


  • 2.  RE: Default route question/issue

     
    Posted 01-01-2022 07:17
    When you configure an interface to be a dhcp client, the client will get the gateway address as part of the dhcp response from the upstream server.  If there is a gateway in the response then the associated default route for that gateway will be installed.

    You don't need to configure one.

    ------------------------------
    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
    http://puluka.com/home
    ------------------------------



  • 3.  RE: Default route question/issue

     
    Posted 01-04-2022 05:28
    Hi Steve, thank you for your reply, as always.

    So, I wish the dhcp assigned gateway on this interface i.e. ge-0/0/7.0, to be the backup route (qualified-next-hop), so are you saying I do not need to specify anything other than the primary route (next-hop #.#.#.#;) for this design to work?

    i.e. 

    routing-options {
        static {
            route 0.0.0.0/0 {
                next-hop #.#.#.#;
            }
        }
        router-id #.#.#.#;
    }​​​



  • 4.  RE: Default route question/issue

     
    Posted 01-04-2022 05:31
    When you are using dhcp on an interface there literally is no configuration at all of the static route.  

    This is simply learned from the dhcp server parameter gateway during the dhcp process.

    Now if you want a second default route out a different interface as a backup, then you would configure that static route out the alternative interface.  The routing preference of the dhcp one will come first by default.

    ------------------------------
    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
    http://puluka.com/home
    ------------------------------



  • 5.  RE: Default route question/issue

     
    Posted 01-04-2022 09:12
    Thank you.

    Ok, so in my code above I have my desired config i.e. the static interface is my primary route, and the dhcp client interface as my backup. So, given what you have stated above, how do I ensure the dhcp one will come second?

    Furthermore, how do I propagate my desired routing options to DHCP clients on internal irb interfaces?


  • 6.  RE: Default route question/issue

     
    Posted 01-19-2022 10:51

    Ok, further investigation shows the DHCP route as secondary, and as [Access-internal/12]. However, clients on the internal irb interfaces are unable to route out via this connection when the primary one goes down. In addition, if I try to ping out from the associated interface i.e. ge-0/0/7.0, I receive an error that there is no route to host.  However, if I connect my laptop to this connection, I am able to access the internet e.g. ping an IP address, browse the web etc.

    Here is some relevant information:-

    [Access-internal/12] 00:17:18
    > to 10.100.0.1 via ge-0/0/7.0​
    Interface               Admin Link Proto    Local                 Remote
    ge-0/0/7.0              up    up   inet     10.100.32.116/14

    Please can someone help?


  • 7.  RE: Default route question/issue

    Posted 02-07-2022 19:13
    Hi there,

    Were you able to get this resolved?

    ------------------------------
    ABRAHAM VELA
    ------------------------------