[j-nsp] GRE Strangeness

[Alex]

Hello there,

"gre" interface is software-based and only officially supported with GMPLS 
on routers, not EX-series.
http://www.juniper.net/techpubs/en_US/junos10.0/information-products/topic-collections/nog-mpls-frr/gmpls-lsp.html
EX switch only got this interface visible because it also runs own JUNOS 
which is somewhat common with routers' JUNOS. EX does not support GRE in 
hardware yet.
HTH
Rgds
Alex


----- Original Message ----- 
From: "Chris" <lists at blackhat.bz>
To: <juniper-nsp at puck.nether.net>
Sent: Tuesday, July 12, 2011 9:07 AM
Subject: [j-nsp] GRE Strangeness


> Hi all,
>
> I have a couple of EX4200's that are stacked currently and I am trying
> to get a GRE tunnel working on them with the destination being a Linux 
> box.
>
> Here is the setup so far:
>
> I have a network of 192.168.1.0/24 behind the Linux box. This network is
> trying to reach 10.10.10.0/24 which is attached to the pair of EX4200's.
> The EX4200's have a tunnel endpoint IP of 10.5.5.1, while the Linux box
> is 10.5.5.2.
>
> The EX4200's have this for the config relevant to the tunnel:
>
> root at acc-core> show configuration interfaces
> ....
> ge-0/0/26 {
>    description "M1Ke-1 CMC1";
>    unit 0 {
>        family ethernet-switching {
>            vlan {
>                members Management;
>            }
>        }
>    }
> }
> ....
> gre {
>    unit 0 {
>        tunnel {
>            source 176.74.24.241;
>            destination 203.170.85.3;
>        }
>        family inet {
>            address 10.5.5.1/30;
>        }
>    }
> }
> ....
> vlan {
>    unit 100 {
>        description "Management VLAN";
>        family inet {
>            address 10.10.10.254/24;
>        }
>    }
> }
> ....
> root at acc-core> show configuration routing-options static
> ...
> route 192.168.1.0/24 next-hop 10.5.5.2;
> ...
> root at acc-core> show configuration vlans
> Management {
>    vlan-id 100;
>    l3-interface vlan.100;
> }
>
> There are no filters currently on them.
>
> The strangeness is as follows:
>
> From the Linux box I can ping 10.5.5.1 (likewise the other way, the
> EX4200's can ping 10.5.5.2).
> From the Linux box I can ping 10.10.10.254 (Juniper vlan.100 interface)
> From the Linux box I CAN'T ping 10.10.10.100 (Device behind Juniper,
> plugged into ge-0/0/26)
> From the Juniper I CAN ping 10.10.10.100
> From the Juniper I CAN ping 192.168.1.254
> From the 10.10.10.100 device, I can't ping 192.168.1.0/24
>
> The source for Linux box pings is 192.168.1.254.
>
> On the Juniper, the routing table shows these entries:
>
> For troubleshooting this issue, the first thing I checked was the routes:
>
> root at acc-core> show route 192.168.1.254
>
> inet.0: 9443 destinations, 9444 routes (9443 active, 0 holddown, 0 hidden)
> Restart Complete
> + = Active Route, - = Last Active, * = Both
>
> 192.168.1.0/24     *[Static/5] 00:36:39
>                    > to 10.5.5.2 via gre.0
>
> I then tryed a traceroute from the 10.10.10.100 device to 192.168.1.254.
> This results in a loop:
>
> traceroute to 192.168.1.254 (192.168.1.254), 30 hops max, 40 byte packets
> 1  10.10.10.254 (10.10.10.254)  1.084 ms  3.707 ms  0.588 ms
> 2  xx.xx.xx.42 (xx.xx.xx.42)  0.412 ms  0.303 ms  0.525 ms
> 3  xx.xx.xx.41 (xx.xx.xx.41)  0.877 ms  0.896 ms  3.826 ms
> 4  xx.xx.xx.42 (xx.xx.xx.42)  3.347 ms  2.971 ms  2.956 ms
> 5  xx.xx.xx.41 (xx.xx.xx.41)  2.557 ms  1.01 ms  1.181 ms
>
> The .41 address is the border of the network, which it shouldnt be going
> to. The border has a route learnt from the EX4200's via iBGP for
> 10.10.10.0/24 to go back to it, so the loop continues. The border is
> giving a default route out to the EX4200's:
>
> root at acc-core> show route 0.0.0.0
>
> inet.0: 9455 destinations, 9456 routes (9455 active, 0 holddown, 0 hidden)
> Restart Complete
> + = Active Route, - = Last Active, * = Both
>
> 0.0.0.0/0          *[BGP/170] 02:44:32, MED 0, localpref 100, from
> 176.74.24.251
>                      AS path: 15830 I
>                    > to 176.74.24.242 via vlan.50
>
> Even with that route there, it should be looking at the more specific
> /24 route that I have added in, I can't see any reason for it to go
> through via the defaults. Has anyone seen this behaviour before? I have
> been pulling my hair out for the last couple of hours trying to figure
> it out, no doubt the problem is something basic after all that.
>
> Thanks
>
> _______________________________________________
> juniper-nsp mailing list juniper-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/juniper-nsp
>