[j-nsp] ssb NH: resolutions from x throttled
Alex
alex.arseniev at gmail.com
Mon May 24 17:22:48 EDT 2010
By saying "probing" I mean someone is sending packets towards Your link' /30 including network (e.g. X.Y.Z.0) and broadcast (e.g. X.Y.Z.3) address. Hence unnecessary resolution requests being throttled.
I suggest You start using /31 or, if that's not possible, drop packets destined to Your link' X.Y.Z.0 and X.Y.Z.3 inbound by means of JUNOS firewall filter.
Rgds
Alex
----- Original Message -----
From: juniper at iber-x.com
To: Alex
Cc: juniper-nsp at puck.nether.net
Sent: Monday, May 24, 2010 7:21 PM
Subject: Re: [j-nsp] ssb NH: resolutions from x throttled
Hi there,
I'm apologize by the delay in my reply.
We have made some test from different Internet route-server and since there we are seeing our networks without any announce problem.
We have also checked if someone is announcing a part of our network with less than /24 but we didn't detect this problem.
Is there another way to check if someone else from Internet is probing our addres block?
Thanks,
El 18/05/2010 20:21, Alex escribió:
Hello there,
I believe someone from Internet could be probing Your address block including network and broadcast IP addresses on frame-relay link. Hence unnecessary "resolutions" are throttled and event logged.
Is it possible to change the /30 to /31? Same for IPv6, I'd suggest to try /126.
If not then I'd suggest to block traffic from Internet to Your /30 with FW filter unless there is a legitimate reason for Internet users to access these IPs.
Regards
Alex
----- Original Message -----
From: juniper at iber-x.com
To: Alex ; juniper-nsp at puck.nether.net
Sent: Tuesday, May 18, 2010 4:43 PM
Subject: Re: [j-nsp] ssb NH: resolutions from x throttled
Hi,
Regardings your questions,
1.- The encapsulation in these interfaces is frame-relay.
2.- Addresses are public and we don't advertise this /30 link to the Internet only the general range of IP.
3.- There isn't the same IPs in other interfaces.
The configuration of this particular interface is:
lt-0/2/0 {
unit 101 {
encapsulation frame-relay;
dlci 100;
peer-unit 100;
family inet {
no-redirects;
address x/30;
}
family iso;
family inet6 {
y/124;
z/64;
}
family mpls;
}
}
Thanks for your time,
El 17/05/2010 20:32, Alex escribió:
Hello there,
May I ask some questions please?
1/ What is the encapsulation on this link?
2/ What are the link IP addresses: public or private? If public do you advertise these link addresses to the Internet at large?
3/ Do these addresses overlap with addresses somewhere else in Your network? Perhaps in VRF?
Regards
Alex
----- Original Message -----
From: juniper at iber-x.com
To: Alex ; juniper-nsp at puck.nether.net
Sent: Monday, May 17, 2010 4:25 PM
Subject: Re: [j-nsp] ssb NH: resolutions from x throttled
Hi,
Our router M20 is divided in two logical routers, one is the physical and the other is the logical. And it is in the logical tunnel interface, lt-0/2/0, where the problem are. And it is only in that two interfaces where we've thought to apply the statement: 'proxy-arp'. What is it your opinion about the implementation in this scenario?
Do you have any other idea to solve this message in our Juniper's log without make a JUNO's upgrade? I would appreciate it because we are trying to solve it for a long time without success.
Thanks,
El 17/05/2010 11:16, Alex escribió:
I am sure You realise "proxy-arp" is an ARP Response function:
Warning: If you configure unrestricted proxy ARP, the proxy router replies to ARP requests for the target IP address on the same interface as the incoming ARP request.
http://www.juniper.net/techpubs/software/junos/junos90/swconfig-network-interfaces/configuring-unrestricted-proxy-arp.html
So if You have another JUNOS box sitting on the same PE-CE subnet with M20, and M20 has traffic coming in from its core-facing interface and addressed to unassigned IP addresses on said subnet, You can always configure "proxy-arp" on that other JUNOS box in order to respond to M20 and keep poor old M20 happy...
Cheers
Alex
----- Original Message ----- From: <juniper at iber-x.com>
To: "Christoph Blecker" <admin at toph.ca>; <juniper-nsp at puck.nether.net>
Sent: Monday, May 17, 2010 10:45 AM
Subject: Re: [j-nsp] ssb NH: resolutions from x throttled
Hello,
Yes, we had read this upgrade recomendation but we are looking for an
alternative solution. How I said, we read that there is a possibility to
set a 'proxy-arp' option for a particular interface
(http://www.juniper.net/techpubs/software/junos/junos90/swconfig-network-interfaces/configuring-unrestricted-proxy-arp.html)
and maybe it exists a statement for the opposite because we think that
perhaps it will solve the 'problem'.
Set this statement is only one idea (probably it doesn't work) but, does
anyone have another idea?
Thanks for your help and time,
El 17/05/2010 10:18, Christoph Blecker escribió:
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Hash: SHA1
Hello,
The issue appears to be a bug in the JUNOS version you are running. A
quick Google search turned up the following:
http://www.juniper.net/techpubs/software/junos/junos73/rn-sw-73/previous-releases.html
"If a router receives rapid multicast traffic from various groups or
sources that do not have entries in the forwarding table, the router
might generate the ?router-name feb NH: resolutions from iif number
throttled? system log message and might delay the installation of
forwarding table entries for some of these multicast packets. [PR/46474:
This issue has been resolved.]"
Solution would be to review your hardware and upgrade your JUNOS version
as applicable. ARP resolution is a normal and necessary funtion of the
router, and you would not want to disable it (I'm not even sure there
*is* a way to disable it withing JUNOS).
Cheers,
- -Christoph
On 10-05-17 01:43 AM, juniper at iber-x.com wrote:
Hi there,
We have a Juniper M20 with JUNOS 7.3R1.4, old version :( .. and since
few we have in our log these entries:
May 10 23:49:48.177 2010 xxxxx ssb NH: resolutions from iif 73 throttled
May 10 23:50:41.168 2010 xxxxx ssb NH: resolutions from iif 88 throttled
..
Someone told us that maybe was a port/ip scan on an Ethernet subnet and
this causes a flood of ARP requests.
We found that there is a statement to set the 'proxy-arp' option:
[edit]
user at host# set interfaces interface-name unit logical-unit-number proxy-arp
But we can't find the opposite statement, I mean that the router doesn't
register any arp resolution in one interface.
Also we read that it was a problem [PR/46474] solved since the version
7.3R3 but we have an older JUNOS version..
Does anyone know how to solve this 'problem'?
Thanks in advance,
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