[j-nsp] Need help on ping output

[Sonny I Franslay]

Hi guy,

Thanks for replying.

> The address 10.254.1.2 is the source of the packets being sent back to
> "router" with ICMP Destination Host Unreachable messages in them.  That
> means that your packets reached a router which had no route to the
> destination host.  I suggest that you identify the location of that
router.

Is it possible that 10.254.1.2 is denying ICMP and thus return the ICMP Dest
Host Unreachable? But it somehow allows other traffic (non-ICMP) through?

Could an ACL might cause this kind of ping reply?

In any case, what does each entry mean? (e.g Vr, HL .etc):

36 bytes from 10.254.1.2: Destination Host Unreachable
Vr HL TOS  Len   ID Flg  off TTL Pro  cks      Src      Dst
 4  5  00 0054 e4db   0 0000  fe  01 2b8d 192.154.21.134  192.154.21.133

>
> You need to check that the interface is actually up and you're not using
> some alternative path to reach destinations "beyond" your ATM link.
>
> I'd also suggest that you check your routing table and forwarding table to
> see what the next hop for 192.168.21.133 is.  If you don't see it using
the
> command "show route <blah>" then try "show route <blah> hidden extensive".
> That might show you that the route is actually being filtered (perhaps
> because 192.168.0.0/16 has been added to your martians?).  If this is the
> case, the packet may be using a default route to reach 10.254.1.2 but, if
> that router is injecting the default, there will be no forwarding path
from
> there.

There is no other path to reach 192.168.21.133. "show route <blah>" shows
that the IP is learned via a connected subnet.

router> show route 192.168.21.133

inet.0:
+ = Active Route, - = Last Active, * = Both

192.168.21.132/30  *[Direct/0] 2d 17:54:22
                    > via at-0/0/0.6

I've checked that the route has not been added to the martian list.

sonny

> > Hi all,
> >
> > Recently I've just upgraded our M5 to Junos 5.3R3.4 from 5.0. Peculiar
> > thing is that one of our ATM pt-pt interface started to behave
> > strangely when we try to ping the neighboring interface. But
> > traffic is
> > still able to transverse via the ATM PVC link normally.
> >
> > Below is the ping output:
> >
> > router> ping interface at-0/0/0.6 192.168.21.133
> > PING 192.168.21.133 (192.168.21.133): 56 data bytes
> > 36 bytes from 10.254.1.2: Destination Host Unreachable
> > Vr HL TOS  Len   ID Flg  off TTL Pro  cks      Src      Dst
> >  4  5  00 0054 bc38   0 0000  fe  01 5430 192.168.21.134
> > 192.168.21.133
> >
> > 36 bytes from 10.254.1.2: Destination Host Unreachable
> > Vr HL TOS  Len   ID Flg  off TTL Pro  cks      Src      Dst
> >  4  5  00 0054 bc79   0 0000  fe  01 53ef 192.168.21.134
> > 192.168.21.133
> >
> > 36 bytes from 10.254.1.2: Destination Host Unreachable
> > Vr HL TOS  Len   ID Flg  off TTL Pro  cks      Src      Dst
> >  4  5  00 0054 bc81   0 0000  fe  01 53e7 192.168.21.134
> > 192.168.21.133
> >
> > ^C
> > --- 192.168.21.133 ping statistics ---
> > 7 packets transmitted, 0 packets received, 100% packet loss
> >
> >
> > No changes were done on the interface config after the junos upgrade.
> > There is no firewall filter configured on the interface either.
> >
> > The config of the interface:
> >
> > [edit]
> > router# show interfaces at-0/0/0 unit 6
> > encapsulation atm-snap;
> > vci 1.40;
> > oam-period 10;
> > family inet {
> >     address 192.168.21.134/30;
> > }
> > family mpls;
> >
> > [edit]
> >
> > I was hoping someone could help me decipher the meaning of
> > the ping output
> > and what is the IP 10.254.1.2 signify?
> >
> > Many thanks in advance.
> >
> >
> > /sonny
> >
> >
> > _______________________________________________
> > juniper-nsp mailing list juniper-nsp@puck.nether.net
> > http://puck.nether.net/mailman/listinfo/juniper-nsp
> >
>
>
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