SRX Services Gateway
SRX Services Gateway

GRE Keepalive

Wednesday

Hi 

I try to monitor GRE status. The output are below 

Logical interface gr-0/0/0.0 (Index 76) (SNMP ifIndex 535)
Flags: Hardware-Down Up Point-To-Point SNMP-Traps 0x0 IP-Header 10.1.2.1:10.1.2.5:47:df:64:0000000000000000
Encapsulation: GRE-NULL
Copy-tos-to-outer-ip-header: Off, Copy-tos-to-outer-ip-header-transit: Off
Gre keepalives configured: On, Gre keepalives adjacency state: up
Input packets : 10716
Output packets: 10711
Security: Zone: tunnel
Allowed host-inbound traffic : bootp bfd bgp dns dvmrp igmp ldp msdp nhrp ospf pgm pim rip router-discovery rsvp sap vrrp dhcp
finger ftp tftp ident-reset http https ike netconf ping reverse-telnet reverse-ssh rlogin rpm rsh snmp snmp-trap ssh telnet
traceroute xnm-clear-text xnm-ssl lsping ntp sip r2cp webapi-clear-text webapi-ssl tcp-encap sdwan-appqoe
Protocol inet, MTU: 1400
Max nh cache: 0, New hold nh limit: 0, Curr nh cnt: 0, Curr new hold cnt: 0, NH drop cnt: 0
Flags: Sendbcast-pkt-to-re, User-MTU
Addresses, Flags: Dest-route-down Is-Preferred Is-Primary
Destination: 10.1.100.0/30, Local: 10.1.100.2, Broadcast: 10.1.100.3

 

Gre keepalives configured: On,

Gre keepalives adjacency state: up < What's meaning for this?  Gre keepalives adjacency state always is up even gr interface (gr-0/0/0) down

3 REPLIES 3
SRX Services Gateway

Re: GRE Keepalive

Wednesday

Hi Halo,

 

Please refer the following technical documentation for GRE Keepalive Time - https://www.juniper.net/documentation/en_US/junos/topics/concept/gre-keepalive-time-overview.html

 

Also, note that, When the hold time expires,

  • The GRE tunnel will stay up even though the interface cannot send or receive traffic.

  • The Link status will be Up and the Gre keepalives adjacency state will be Down.



Thanks,
π00bm@$t€®.
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SRX Services Gateway

Re: GRE Keepalive

Wednesday

Hi Halo,

Is this GRE configured over IPSec on SRX platform?

Can you please share following two output

show version brief
 show oam gre-keepalive interface-name gr-0/0/0.0

Thanks
Vishal

SRX Services Gateway

Re: GRE Keepalive

Wednesday

Halo,

 

As per Juniper documentation the keepalives are processed by the RE. I believe one reason that could explain the behavior could be that the keepalives can still be sent via the underlying interfaces of the GRE interface. These will be the interfaces configured with the IPs highlighted below.

 

gr-0/0/0 {
    unit 0 {
        tunnel {
            source 1.1.1.1;
            destination 2.2.2.1;
        }
        family inet {
            address 192.168.1.1/24;
        }
    }

 

Hence even though the GRE interface is down, the keepalive adjacency state will be up because the keepalives can be still sent without problems.

 

Can you bring down one physical interface and confirm if the keepalive adjacency still shows up?

 

Please mark this comment as the Solution if applicable