[53805] in North American Network Operators' Group
Broken Netmask?
daemon@ATHENA.MIT.EDU (Palmer, John)
Wed Nov 27 16:22:53 2002
From: "Palmer, John" <jpalmer@utilinc.com>
To: nanog@merit.edu
Date: Wed, 27 Nov 2002 15:06:55 -0600
Errors-To: owner-nanog-outgoing@merit.edu
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We have a /23 (199.5.156/23) and seem to be having a problem with our ISP
(Network Access Solutions - NAS) .
We do not do our own route advertising - they do it for us and route the
block to our connection.
The problem is that the second part of the block (199.5.157.0 -
199.5.157.255) seems to be mis-routed within the ISP's network. I think its
a netmask problem.
The symptoms are that packets get through from some destinations and not
from others. Also, packets sometimes fail based on port numbers (ie: if I
come from x.y.z.w to 199.5.157.x on port 80, it works but not from x.y.z.w
to 199.5.157.x on port 25) Furthermore, the port and source addresses that
have problems changes over time (ie: x.y.z.w to port 25 will work
tommorrow). We dont block these ports nor do they.
NAS seems to be light on technical talent and can't seem to solve this
problem.
Interesting note, if you check 199.5.157.1 bgp from any of the looking glass
websites you get multiple occurrences of NAS (and other AS numbers): ie:
(from AADS)
BGP routing table entry for 199.5.156.0/23, version 6041537
Paths: (6 available, best #1)
Advertised to peer-groups:
AS4544-INTERNAL AS4544-CLIENT AS4544-HOT-ROUTE AS4544-DATA-CENTER
AS4544-CORE-CUSTOMER-FULL
16631 16631 16631 13953 13953 13953 13953 13953 13953
206.220.243.177 from 206.220.243.177 (66.28.1.8)
Origin IGP, metric 100, localpref 80, valid, external, best
Community: 4544:300
16631 16631 16631 13953 13953 13953 13953 13953 13953, (received-only)
206.220.243.177 from 206.220.243.177 (66.28.1.8)
Origin IGP, metric 30802, localpref 100, valid, external
16631 16631 16631 13953 13953 13953 13953 13953 13953, (received & used)
206.204.251.196 (metric 113851) from 206.204.251.196 (206.204.251.196)
Origin IGP, metric 100, localpref 80, valid, internal
Community: 4544:300 4544:5005
16631 16631 16631 13953 13953 13953 13953 13953 13953, (received & used)
206.204.251.206 (metric 43484) from 206.204.251.206 (206.204.251.206)
Origin IGP, metric 100, localpref 80, valid, internal
Community: 4544:300 4544:5001
6461 16631 16631 16631 13953 13953 13953 13953 13953 13953
206.220.243.71 from 206.220.243.71 (207.126.96.35)
Origin IGP, metric 110, localpref 80, valid, external
Community: 4544:300
6461 16631 16631 16631 13953 13953 13953 13953 13953 13953,
(received-only)
206.220.243.71 from 206.220.243.71 (207.126.96.35)
Origin IGP, metric 1295, localpref 100, valid, external
Notice the multiple occurrences of 16631 and 13953. I know there are valid
reasons to add multiple occurrences, but can anyone tell if this is broken?
These duplicate numbers are new - they were'nt there before (when things
worked).
The intermittant failure problem reminds me of a time when someone's IGRP
had a bad netmask somwhere. I'm wondering if they may have a /24 netmask
internally somewhere and not a /23 like they should.
Any help would be appreciated. NAS doesn't seem to have a clue.
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<div class=3DSection1>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'>We
have a /23 (199.5.156/23) and seem to be having a problem with our ISP =
(Network
Access Solutions - NAS<span class=3DGramE>) =
.</span><o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier =
New"'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'>We
do not do our own route advertising - they do it for us and route the =
block to
our connection.<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier =
New"'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'>The
problem is that the second part of the block (199.5.157.0 - =
199.5.157.255)
seems to be mis-routed within the ISP's network. I think <span =
class=3DGramE>its</span>
a netmask problem.<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier =
New"'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'>The
symptoms are that packets get through from some destinations and not =
from
others. Also, packets sometimes fail based on port numbers (ie: if I =
come from
x.y.z.w to 199.5.157.x on port 80, it works but not from x.y.z.w to =
199.5.157.x
on port 25) Furthermore, the port and source addresses that have =
problems
changes over time (ie: x.y.z.w to port 25 will work tommorrow). We =
<span
class=3DGramE>dont block</span> these ports nor do =
they.<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier =
New"'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'>NAS
seems to be light on technical talent and can't seem to solve this =
problem.<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier =
New"'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'>Interesting
note, if you check 199.5.157.1 bgp from any of the looking glass =
websites you
get multiple occurrences of NAS (and other AS numbers): ie: (from =
AADS)<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier =
New"'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'>BGP
routing table entry for 199.5.156.0/23, version =
6041537<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'>Paths:
(6 available, best #1)<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>Advertised to =
peer-groups:<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> =
</span>AS4544-INTERNAL AS4544-CLIENT
AS4544-HOT-ROUTE AS4544-DATA-CENTER<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> =
</span>AS4544-CORE-CUSTOMER-FULL<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>16631 16631 16631 13953 13953 =
13953 13953
13953 13953<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>206.220.243.177 =
from 206.220.243.177
(66.28.1.8)<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>Origin =
IGP, metric 100, localpref 80,
valid, external, best<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> =
</span>Community: 4544:300<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>16631 16631 16631 13953 13953 =
13953 13953
13953 13953, (received-only)<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>206.220.243.177 =
from 206.220.243.177
(66.28.1.8)<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>Origin =
IGP, metric 30802, localpref 100,
valid, external<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>16631 16631 16631 13953 13953 =
13953 13953
13953 13953, (received & used)<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>206.204.251.196 =
(metric 113851) from
206.204.251.196 (206.204.251.196)<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>Origin =
IGP, metric 100, localpref 80,
valid, internal<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> =
</span>Community: 4544:300 4544:5005<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>16631 16631 16631 13953 13953 =
13953 13953
13953 13953, (received & used)<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>206.204.251.206 =
(metric 43484) from 206.204.251.206
(206.204.251.206)<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>Origin =
IGP, metric 100, localpref 80,
valid, internal<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> =
</span>Community: 4544:300 4544:5001<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>6461 16631 16631 16631 13953 =
13953 13953
13953 13953 13953<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>206.220.243.71 =
from 206.220.243.71
(207.126.96.35)<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>Origin =
IGP, metric 110, localpref 80,
valid, external<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> =
</span>Community: 4544:300<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>6461 16631 16631 16631 13953 =
13953 13953
13953 13953 13953, (received-only)<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>206.220.243.71 =
from 206.220.243.71
(207.126.96.35)<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'><span
style=3D'mso-spacerun:yes'> </span>Origin =
IGP, metric 1295, localpref 100,
valid, external<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier =
New"'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'>Notice
the multiple occurrences of 16631 and 13953. I know there are valid =
reasons to
add multiple occurrences, but can anyone tell if this is broken? These
duplicate numbers are new - they were'nt there before (when things =
worked).<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier =
New"'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'>The
intermittant failure problem reminds me of a time when someone's IGRP =
had a bad
netmask somwhere. I'm wondering if they may have a /24 netmask =
internally
somewhere and not a /23 like they should.<o:p></o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier =
New"'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal =
style=3D'mso-layout-grid-align:none;text-autospace:none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier New"'>Any
help would be appreciated. NAS doesn't seem to have a =
clue.<o:p></o:p></span></font></p>
<p class=3DMsoNormal style=3D'mso-layout-grid-align:none;text-autospace:=
none'><font
size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;font-family:"Courier =
New"'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
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