Routing

IMPORTANT MODERATION NOTICE

This community is currently under full moderation, meaning  all posts will be reviewed before appearing in the community. Please expect a brief delay—there is no need to post multiple times. If your post is rejected, you'll receive an email outlining the reason(s). We've implemented full moderation to control spam. Thank you for your patience and participation.



Expand all | Collapse all

Advertising Static route Discard via BGP showing as hidden

  • 1.  Advertising Static route Discard via BGP showing as hidden

    Posted 08-05-2021 16:16
    Hi,

    I have a requirement where I need to create a source NAT pool where the addresses/prefixes are not built on any interfaces. I then need to advertise this NAT pool via BGP to an adjacent SRX4600.

    To get around this I have created a static route with next-hop discard to install the route in the table. I then add the NAT pool network to a policy statement and apply this to the BGP peer export list.

    The problem is on the adjacent SRX4600 the NAT pool route only shows when running show route receive-protocol bgp hidden. Why is this route showing as hidden and what could be the workaround so it appears as an active route?

    ------------------------------
    Jack
    ------------------------------


  • 2.  RE: Advertising Static route Discard via BGP showing as hidden

    Posted 08-05-2021 16:56
    Routes can be hidden for a number of reasons.. From the sounds of your setup it's probably to do with the next-hop being invalid.

    FYI some info for your perusal:

    https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/troubleshooting-bgp-sessions.html

    • The next hop cannot be resolved using the current indirect next hop resolution rule. Because routing protocols such as internal BGP (IBGP) can send routing information about indirectly connected routes, Junos OS relies on routes from intra-AS routing protocols (OSPF, IS-IS, RIP, and static) to resolve the best directly connected next hop. The Routing Engine performs route resolution to determine the best directly connected next hop and installs the route to the Packet Forwarding Engine.




  • 3.  RE: Advertising Static route Discard via BGP showing as hidden

     
    Posted 08-05-2021 17:20
    If this is an iBGP session you might need to add the next hop self to the policy for the advertisement.

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



  • 4.  RE: Advertising Static route Discard via BGP showing as hidden

    Posted 08-06-2021 05:26
    You need to find the 'reason' for the route being hidden, this is done with the show route <X> hidden extensive as well as the show route receiving-protocol <BGP> <PEER IP> hidden extensive commands.

    Most common failures are next-hop recursion failure, which could potentially be your case, but first find out the reason why with those two commands mentioned.

    Elvin