[j-nsp] RE : Strange IS-IS Problem

david.roy at orange-ftgroup.com david.roy at orange-ftgroup.com
Sun Mar 7 03:19:12 EST 2010


Hi 

Did you try to check via Tcpdump on your MX, the size of the MX ISIS Hello packet (with the hello padding) ? 

Regards,
 David

________________________________________
De : juniper-nsp-bounces at puck.nether.net [juniper-nsp-bounces at puck.nether.net] de la part de Derick Winkworth [dwinkworth at att.net]
Date d'envoi : dimanche 7 mars 2010 07:25
À : Eric Van Tol; Juniper-Nsp
Objet : Re: [j-nsp] Strange IS-IS Problem

If its JUNOS, then just configure the MTU normally in the interface config on the switch.



________________________________
From: Eric Van Tol <eric at atlantech.net>
To: Juniper-Nsp <juniper-nsp at puck.nether.net>
Sent: Sat, March 6, 2010 3:07:23 PM
Subject: Re: [j-nsp] Strange IS-IS Problem

Answers to several questions from various sources below:

> - If you have an aggregate between switches, routers... make sure they
> are correctly configured from both sides?

The EX2500s are connected together via two 10G ports, aggregated into a portchannel.  No errors on that or the interfaces on the EX2500s.

> - Also Try to check duplex.

Duplex is not a problem.

> - Is there is possibility to connect the routers directly? This will
> isolate the problem.

There is, but I am not physically in front of the routers at the moment.  My next test on Monday was to connect the J2320 up to ge-1/0/0 on the MX960.

> What happens when you reduce the physical MTUs on the MX and the
> J-Series to something smaller?  Same behavior?

Unfortunately, yes, I get the same behavior.

> Are the EX2500's configured for jumbos?

I thought of this earlier and checked the documentation, but while it does state that the EX2500 supports jumbo frames, there is absolutley nothing in the docs that says how to configure this feature.  A search for 'jumbo' yields two hits and a search for 'mtu' yields nothing.  I *can* ping from one router to the other with 1472-byte packets with the df-bit set, so I know that my 1500-byte packet can get through no problem.

> Try adding the point-to-point command under protocols Isis xxx
> interface.

This does nothing, unfortunately.  Besides, the original setup was supposed to be that xe-1/2/0.1 be in a bridge-group with interface irb.1 as its routing interface, so point-to-point wouldn't meet my end goal.  When that didn't work, I simplified it for troubleshooting to just be a plain vlan trunk routed interface.

> Can you try configuring family iso mtu 1500?

I've tried 1497 and 1500 to no avail. :-(

My feeling is that there is something happening inside the EX2500s of which I am not aware.  These are brand new switches that I've no experience configuring, but I would think that if I can ping through them after configuring trunk and portchannel interfaces, that there'd really be no other config necessary in this very simple topology (besides MSTP).

Thanks to all for your suggestions thus far.

-evt

> -----Original Message-----
> From: Walaa Abdel razzak [mailto:walaaez at bmc.com.sa]
> Sent: Saturday, March 06, 2010 8:24 AM
> To: Eric Van Tol; Juniper-Nsp
> Subject: RE: [j-nsp] Strange IS-IS Problem
>
> Hi
>
> - If you have an aggregate between switches, routers... make sure they
> are correctly configured from both sides?
> - Also Try to check duplex.
> - Is there is possibility to connect the routers directly? This will
> isolate the problem.
>
> Best Regards,
> Walaa Abdel Razzak
>
> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net
> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Eric Van Tol
> Sent: Saturday, March 06, 2010 3:54 PM
> To: Juniper-Nsp
> Subject: [j-nsp] Strange IS-IS Problem
>
> Hi all,
> I've got a strange ISIS problem and I'm hoping another set of eyes can
> help me identify what is wrong here.  I've got an MX960 logically
> connected to a J2320 through two EX2500 switches:
>
> MX960 <==> EX2500 <==> EX2500 <==> J2320
>
> I'm simply trying to get ISIS working between the two routers and it's
> not coming up.  Traceoptions don't show anything out of the ordinary.
>
> MX960:
> xe-1/2/0 {
>     vlan-tagging;
>     mtu 9192;
>     unit 1 {
>         vlan-id 1;
>         family inet {
>             mtu 1500;
>             address x.x.x.99/28;
>         }
>         family iso;
>     }
> }
> lo0 {
>     unit 0 {
>         family inet {
>             address 127.0.0.1/32;
>             address x.x.x.74/32;
>         }
>         family iso {
>             address 47.0001.xxxx.xxxx.xxxx.00;
>         }
>     }
> }
> ...
> protocols {
>     isis {
>         interface xe-1/2/0.1;
>         interface lo0.0 {
>             passive;
>         }
>     }
> }
>
>
> J2320:
> ge-0/0/0 {
>     vlan-tagging;
>     mtu 9192;
>     unit 1 {
>         vlan-id 1;
>         family inet {
>             mtu 1500;
>             address x.x.x.100/28;
>         }
>         family iso;
>     }
> }
> lo0 {
>     unit 0 {
>         family inet {
>             address 127.0.0.1/32;
>             address x.x.x.75/32;
>         }
>         family iso {
>             address 47.0001.xxxx.xxxx.xxxx.00;
>         }
>     }
> }
> ...
> protocols {
>     isis {
>         interface ge-0/0/0.1;
>         interface lo0.0 {
>             passive;
>         }
>     }
> }
>
> I can ping fine between the two:
>
> root at router1# run ping x.x.x.99 source x.x.x.100
> PING x.x.x.99 (x.x.x.99): 56 data bytes
> 64 bytes from x.x.x.99: icmp_seq=0 ttl=64 time=4.890 ms
> 64 bytes from x.x.x.99: icmp_seq=1 ttl=64 time=2.098 ms
> 64 bytes from x.x.x.99: icmp_seq=2 ttl=64 time=2.095 ms
> 64 bytes from x.x.x.99: icmp_seq=3 ttl=64 time=2.130 ms
> 64 bytes from x.x.x.99: icmp_seq=4 ttl=64 time=4.217 ms
> ^C
> --- x.x.x.99 ping statistics ---
> 5 packets transmitted, 5 packets received, 0% packet loss
> round-trip min/avg/max/stddev = 2.095/3.086/4.890/1.217 ms
>
> If I monitor traffic on either of the interfaces, I see ISIS packets
> leaving, but nothing coming in.  The EX2500s have a very vanilla config
> and I'm doing no filtering on them.
>
> Any ideas?
>
> Thanks,
> evt
>
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