From: paul cosgrove (paul.cosgrove@gmail.com)
Date: Tue Dec 02 2008 - 00:23:28 ARST
Hi Howard, That helps a lot, many thanks for checking. I suppose to
completely close this off you could check that 223 is accepted (if you
haven't already). You might also confirm that you increased the eigrp
metric maximum-hops to 255. The default is 100 according to the command
reference.
Paul.
On Mon, Dec 1, 2008 at 5:39 PM, Howard Hooper <Howard.Hooper@dupre.co.uk>wrote:
> Hi All,
>
> I've found another link for the EIGRP packet generator listed under
> 'EIGRP Tools' here
> http://www.arhont.com/ViewPage7422.html?siteNodeId=3&languageId=1&conten
> tId=-1<http://www.arhont.com/ViewPage7422.html?siteNodeId=3&languageId=1&contentId=-1>
>
> I carried out a few tests using dynamips on a linux machine connected to
> an external router, as soon as the neighbor relationship is up between
> them both I then used the packet generator to spoof update messages;
>
> The following is an output from the packet generator config file, I
> raised the 'Hop Count' to 224 as shown below, the output I received on
> the router is below also.
>
> !!!!!from config file!!!!!
> #Metric
> $k1="1";
> $k2="0";
> $k3="1";
> $k4="0";
> $k5="0";
> $holdtime="15";
> $mtu="1514";
> $hopcount="224"
> !
> !
> !!!!!!Output from router after receiving the Update message!!!!
> !
> 15w1d: EIGRP: Received UPDATE on Vlan11 nbr 192.168.2.63
> 15w1d: AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ
> un/rely 0/0
> 15w1d: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming UPDATE
> packet
> 15w1d: IP-EIGRP(Default-IP-Routing-Table:1): Ext 192.168.67.201/32 M
> 4294967295
> - 512 4294967295 SM 4294967295 - 512 100
> !
> !!!! nothing in the topology table !!!!!
> IP-EIGRP Topology Table for AS(1)/ID(192.168.30.254)
>
> Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
> r - reply Status, s - sia Status
>
> P 192.168.2.0/23, 1 successors, FD is 2816
> via Connected, Vlan11
>
> I then changed the hop count to a lower value and re-sent the update,
> this time the router installed the route into it's routing table
>
> 15w1d: EIGRP: Received UPDATE on Vlan11 nbr 192.168.2.63
> 15w1d: AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ
> un/rely 0/0
> 15w1d: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming UPDATE
> packet
> 15w1d: IP-EIGRP(Default-IP-Routing-Table:1): Ext 192.168.67.201/32 M
> 2916 - 2560
> 356 SM 612 - 512 100
> 15w1d: DUAL: dest(192.168.67.201/32) not active
> 15w1d: DUAL: rcvupdate: 192.168.67.201/32 via 192.168.2.63 metric
> 2916/612
> 15w1d: DUAL: Find FS for dest 192.168.67.201/32. FD is 4294967295, RD is
> 4294967
> 295 found
> 15w1d: IP-EIGRP(Default-IP-Routing-Table:1): route installed for
> 192.168.67.201
> ()
> 15w1d: DUAL: RT installed 192.168.67.201/32 via 192.168.2.63
> 15w1d: DUAL: Send update about 192.168.67.201/32. Reason: metric chg
> 15w1d: DUAL: Send update about 192.168.67.201/32. Reason: new if
> 15w1d: EIGRP: Enqueueing UPDATE on Vlan11 iidbQ un/rely 0/1 serno 4-4
> !
> !!! Topology table !!!!
> P 192.168.2.0/23, 1 successors, FD is 2816
> via Connected, Vlan11
> P 192.168.67.201/32, 1 successors, FD is 2916
> via 192.168.2.63 (2916/612), Vlan11
>
>
> I hope this helps.
>
> Howard
>
> ---Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Gary Duncanson
> Sent: 01 December 2008 11:11
> To: paul cosgrove
> Cc: Scott M Vermillion; tim@1c-solutions.com; Cisco certification
> Subject: Re: EIGRP Maximum-hop
>
> Paul,
>
> All roads lead to dead link in Russia it seems apart from this link that
>
> offers a download of a couple of tar files..
>
> http://www.hacker-soft.net/Soft/Soft_2313.htm
>
>
> For those on the list interested in TLV and don't have Doyle rhyshaden
> has
> some good schmatics of the headers..
>
> http://www.rhyshaden.com/eigrp.htm
> ----- Original Message -----
> From: "paul cosgrove" <paul.cosgrove@gmail.com>
> To: "Scott M Vermillion" <scott_ccie_list@it-ag.com>
> Cc: "Timothy Chin" <Tim@1c-solutions.com>; "Oleg Konovalov"
> <OKonovalov@delta.ge>; "Cisco certification" <ccielab@groupstudy.com>
> Sent: Monday, December 01, 2008 9:38 AM
> Subject: Re: EIGRP Maximum-hop
>
>
> > Sorry, that link is dead. Not sure where eigrp tools can be found
> now.
> >
> > Paul.
> >
> > On Mon, Dec 1, 2008 at 9:32 AM, paul cosgrove
> > <paul.cosgrove@gmail.com>wrote:
> >
> >> Hi Scott,
> >>
> >> I was thinking of generating a packet as if it had passed over that
> >> number
> >> of hops, rather than using an actual network.
> >> You can get tools to do that kind of thing for most protocols and
> there
> >> is
> >> indeed one for eigrp:-
> >>
> >> http://www.hackingciscoexposed.com/tools/eigrp-tools.tar.gz
> >>
> >> Paul.
> >>
> >>
> >> On Mon, Dec 1, 2008 at 12:12 AM, Scott M Vermillion <
> >> scott_ccie_list@it-ag.com> wrote:
> >>
> >>> Hi again Paul!
> >>>
> >>> Hop count is actually carried in the EIGRP "IP Internal Routes TLV"
> and
> >>> the
> >>> "IP External Routes TLV" (Doyle Vol I is a great reference for this
> and
> >>> similar such topics). A router advertises a directly connected
> network
> >>> with
> >>> a hop count of zero and it's incremented from there by subsequent
> >>> routers
> >>> learning of that network. When a router receiving an update
> increments
> >>> hop
> >>> count and the resulting value exceeds the locally configured max-hop
> >>> value,
> >>> it will be marked unreachable with a delay of 0xFFFFFF. I don't
> believe
> >>> that any update is sent on regarding that route with a delay of
> >>> 0xFFFFFF -
> >>> I
> >>> believe this to be a completely local affair on a router-by-router
> >>> basis.
> >>> But I could be wrong on that last count. Semantics at that point
> >>> anyway.
> >>>
> >>> So I'd think that you'd either need a really big EIGRP network to
> test
> >>> what
> >>> the truly maximum implemented value might be or you'd need a means
> to
> >>> manipulate the "Hop Count" field in the TLV. I'm not aware that this
> can
> >>> be
> >>> manipulated in a route-map or any such thing...
> >>>
> >>> Cheers,
> >>>
> >>> Scott
> >>>
> >>>
> >>> -----Original Message-----
> >>> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> >>> paul
> >>> cosgrove
> >>> Sent: Sunday, November 30, 2008 2:29 PM
> >>> To: Timothy Chin
> >>> Cc: Oleg Konovalov; Cisco certification
> >>> Subject: Re: EIGRP Maximum-hop
> >>>
> >>> p.s. I should have said we need to set maximum hops to 255 and
> generate
> >>> a
> >>> packet as if it has passed over >224 hops. IPv6 hop limit, like
> TTL,
> >>> count
> >>> down not up.
> >>>
> >>>
> >>> On Sun, Nov 30, 2008 at 9:15 PM, paul cosgrove
> >>> <paul.cosgrove@gmail.com>wrote:
> >>>
> >>> > Hi Timothy,
> >>> >
> >>> > Thanks for the link. The paragraph which explains the 224 limit
> is
> >>> > incorrect in that the Transport Control Field does not exist in IP
> or
> >>> IPv6
> >>> > headers. The IPX TC header field functions like a hop count, and
> IPX
> >>> > packets with a TC of 16 are dropped, hence the need for a
> workaround
> >>> > if
> >>> > packets need to be sent further. The TTL in IP, or hop limit in
> IPv6
> >>> both
> >>> > allow 255 hops so there is no need to do that.
> >>> > The text looks to have been incorrectly copied from the old
> >>> documentation.
> >>> > The IPX workaround is explained in the old EIGRP paper at
> >>> >
> >>> http://ccrg.soe.ucsc.edu/<
> >>> http://ccrg.soe.ucsc.edu/publications/interop94.pd
> >>> f <http://ccrg.soe.ucsc.edu/publications/interop94.pdf>>
> >>> >
> >>> publications/interop94.pdf<
> >>> http://ccrg.soe.ucsc.edu/publications/interop94.p
> >>> df>
> >>> > and all the references I've seen to 224 appear to have been
> >>> derived/copied
> >>> > from that text. I've left a comment on the web page that it needs
> >>> updating.
> >>> >
> >>> > Since the documentation about the max hop limit is conflicting,
> some
> >>> > of
> >>> it
> >>> > must be incorrect. My guess is that the limit is indeed 255, but
> the
> >>> only
> >>> > way we will know for sure is to generate an eigrp packet with the
> hop
> >>> limit
> >>> > set above 224 and see if other routers consider the advertisement
> as
> >>> valid.
> >>> >
> >>> > Paul.
> >>> >
> >>> >
> >>> > On Sun, Nov 30, 2008 at 7:05 PM, Timothy Chin
> <Tim@1c-solutions.com
> >>> >wrote:
> >>> >
> >>> >> Hi,
> >>> >>
> >>> >>
> >>> >>
> >>> >> I know there has been conflicting information on this for awhile.
> I
> >>> don't
> >>> >> know why but the 12.4 command reference for IPv4 doesn't provide
> this
> >>> >> information but the IPv6 reference does specify the maximum
> network
> >>> width:
> >>> >>
> >>> >>
> >>> >>
> >>> >>
> >>> >>
> >>>
> >>>
> http://www.cisco.com/en/US/docs/ios/ipv6/configuration/guide/ip6-eigrp_p
> s644<http://www.cisco.com/en/US/docs/ios/ipv6/configuration/guide/ip6-eigrp_ps644>
> >>>
> 1_TSD_Products_Configuration_Guide_Chapter.html<http://www.cisco.com/en/
> US/docs/ios/ipv6/configuration/guide/ip6-eigrp_ps6441_TSD_Products_Confi
> guration_Guide_Chapter.html<http://www.cisco.com/en/US/docs/ios/ipv6/configuration/guide/ip6-eigrp_ps6441_TSD_Products_Configuration_Guide_Chapter.html>
> >
> >>> >>
> >>> >>
> >>> >>
> >>> >> I don't see an update on the 12.4 IPv4 documentation regarding
> this
> >>> >> but
> >>> >> going by previous releases I figure it would still be the same.
> From
> >>> what
> >>> I
> >>> >> know a maximum hop count of 255 can be configured but traffic
> would
> >>> only
> >>> >> traverse 224.
> >>> >>
> >>> >>
> >>> >> ------------------------------
> >>> >>
> >>> >> *From:* paul cosgrove [mailto:paul.cosgrove@gmail.com]
> >>> >> *Sent:* Sunday, November 30, 2008 12:56 PM
> >>> >> *To:* Timothy Chin
> >>> >> *Cc:* Oleg Konovalov; Cisco certification
> >>> >> *Subject:* Re: EIGRP Maximum-hop
> >>> >>
> >>> >>
> >>> >>
> >>> >> Hi Timothy,
> >>> >>
> >>> >> Just wondering if you have verified that?
> >>> >>
> >>> >> I know there is conflicting information about this point but the
> 12.4
> >>> >> command reference says the limit is 255.
> >>> >>
> >>> >>
> >>>
> >>>
> http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_eig2.h
> tml#
> >>>
> wp1011619<http://www.cisco.com/en/US/docs/ios/iproute/command/reference/
> irp_eig2.html#wp1011619<http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_eig2.html#wp1011619>
> >
> >>> >>
> >>> >> Also the field is indeed 8 bits long in the packets (see figure
> 4-7).
> >>> >> http://oreilly.com/catalog/iprouting/chapter/ch04.html
> >>> >>
> >>> >> The following paper mentions the limit of 224, but only as a
> >>> >> workaround
> >>> >> used on IPX networks to overcome limitations of IPX.
> >>> >> http://ccrg.soe.ucsc.edu/publications/interop94.pdf
> >>> >>
> >>> >> Paul.
> >>> >>
> >>> >> On Sun, Nov 30, 2008 at 12:49 PM, Timothy Chin
> <Tim@1c-solutions.com>
> >>> >> wrote:
> >>> >>
> >>> >> The maximum definable hop count is 255 but 224 hops is the true
> >>> >> limit.
> >>> >>
> >>> >>
> >>> >>
> >>> >> -----Original Message-----
> >>> >> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> Behalf
> >>> Of
> >>> >> Oleg Konovalov
> >>> >> Sent: Sunday, November 30, 2008 5:05 AM
> >>> >> To: Cisco certification
> >>> >> Subject: EIGRP Maximum-hop
> >>> >>
> >>> >> Hi all, I have question about EIGRP maximum hops, based on
> >>> >>
> >>>
> http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080
> >>> >>
> >>> 094cb<
> >>>
> http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a00
> >>> 80094cb>
> >>> >> 7.shtml we can set up maximum 220 hops, based on some CCNP
> materials
> >>> >> it
> >>> >> is
> >>> >> 224. I test it on my router and 255 hops was OK.
> >>> >>
> >>> >> Routing Protocol is "eigrp 100"
> >>> >> Outgoing update filter list for all interfaces is not set
> >>> >> Incoming update filter list for all interfaces is not set
> >>> >> Default networks flagged in outgoing updates
> >>> >> Default networks accepted from incoming updates
> >>> >> EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
> >>> >> EIGRP maximum hopcount 100
> >>> >> EIGRP maximum metric variance 1
> >>> >> Redistributing: eigrp 100
> >>> >> EIGRP NSF-aware route hold timer is 240s
> >>> >> Automatic network summarization is in effect
> >>> >> Maximum path: 4
> >>> >> Routing for Networks:
> >>> >> Routing Information Sources:
> >>> >> Gateway Distance Last Update
> >>> >> Distance: internal 90 external 170
> >>> >>
> >>> >>
> >>> >> Then I have changed metric maximum-hops
> >>> >>
> >>> >> Router(config)#router eigrp 100
> >>> >> Router(config-router)#metric maximum-hops 255
> >>> >> Router(config-router)#end
> >>> >> Router#sh ip protocols
> >>> >> Routing Protocol is "eigrp 100"
> >>> >> Outgoing update filter list for all interfaces is not set
> >>> >> Incoming update filter list for all interfaces is not set
> >>> >> Default networks flagged in outgoing updates
> >>> >> Default networks accepted from incoming updates
> >>> >> EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
> >>> >> EIGRP maximum hopcount 255
> >>> >> EIGRP maximum metric variance 1
> >>> >> Redistributing: eigrp 100
> >>> >> EIGRP NSF-aware route hold timer is 240s
> >>> >> Automatic network summarization is in effect
> >>> >> Maximum path: 4
> >>> >> Routing for Networks:
> >>> >> Routing Information Sources:
> >>> >> Gateway Distance Last Update
> >>> >> Distance: internal 90 external 170
> >>> >>
> >>> >>
> >>> >> Blogs and organic groups at http://www.ccie.net
> >>> >>
> >>> >>
> _______________________________________________________________________
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