From: Bruce Lee (ccie.sp.vn@gmail.com)
Date: Sat Dec 17 2005 - 02:49:59 GMT-3
Hi Arun,
I had tested that lab before, and I have a conlution that we cannot use DIS
manipulation. After your mail, I tested it again and I have the same result.
All SPOKEs have neghbor relationship with HUB, all the routers have the same
database but only HUB have full routes. Using debug isis spf, I see ISIS put
HUB only on PATH and TEN LIST. I think we have the different result from
OSPF because ISIS using CLNS to make neighbor. I don't save the
configuration, but I'm sure I put fram-relay map clns broadcast to make
neighbor.
Please correct me if I'm wrong.
Thanks.
-----Original Message-----
From: Arun Arumuganainar [mailto:aarumuga@hotmail.com]
Sent: Saturday, December 17, 2005 11:57 AM
To: Bruce Lee; 'Andrew Lissitz (alissitz)'; 'Paresh Khatri';
comserv@groupstudy.com; ccielab@groupstudy.com
Subject: Re: ISIS -over NBMA
Hi Bruce ,
Could pls. send me your configuration.
Just wanted to check if you have configured frame-relay map statement for
CLNS with broadcast enabled .
Thanks and Regards
Arun
----- Original Message -----
From: "Bruce Lee" <ccie.sp.vn@gmail.com>
To: "'Arun Arumuganainar'" <aarumuga@hotmail.com>; "'Andrew Lissitz
(alissitz)'" <alissitz@cisco.com>; "'Paresh Khatri'"
<Paresh.Khatri@aapt.com.au>; <comserv@groupstudy.com>;
<ccielab@groupstudy.com>
Sent: Saturday, December 17, 2005 5:04 AM
Subject: RE: ISIS -over NBMA
> Hi Arun and Group,
> With DIS manipulation on L1 or L2 subnet, the partial mesh NBMA still
> doesn't work.
>
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Arun
> Arumuganainar
> Sent: Tuesday, December 13, 2005 3:50 PM
> To: Andrew Lissitz (alissitz); Paresh Khatri; comserv@groupstudy.com;
> ccielab@groupstudy.com
> Subject: Re: ISIS -over NBMA
>
> Hi Andrew ,
>
> Your question is about ISIS over NBMA . Hence I am changing the title of
the
> thread
>
> Pls. Note : I have done this as it will be useful for people who will be
> searching the archives in the future .
>
> Let us say logical topology looks like this
> s2/0 s2/0 s2/0 s2/0
> R1--------R2-------R3
> DLCI : 102 203
>
> Here R2's s2/0 is connected to R1 and R3's S2/0 with DLCI 102 and 103 .
Here
> R2 is HUB and R1 and R3 are the spoke .
>
> Cisco Recommendation : Use always the point-to-point Subinterface whenever
> you have partially meshed FR connection . If at all you wanted to use
> multipoint interface you must need a Full Meshed FR connection . However
> Cisco has also suggested work-around for Partially meshed scenarios as
well.
> Design consideration is different for L1-Only or L2-only Subnet . Let us
> discuss one by one .
>
> L1-only Subnet
> ============
>
> Here You will have to manually configure HUB router as your DIS .Choice of
> DIS can be influenced by command "isis priority " command .
>
> Sample configuration :
> **********************
> On Router 2
> interface ser2/0
> ip router isis
> Isis priority 127
> ***********************
>
> Pls. note : This is similar to choosing DR in OSPF NBMA scenario . However
> in OSPF we need to take an extra precaution . i.e In addition to setting
> high priority for DR( HUB router ) , you should also set Zero priority for
> all the spoke routers . This step is not needed in ISIS . This is because
> ISIS DIS election is Pre-emptive in nature .
>
> L2-Only Subnet :-
> ============
> DIS Election Manipulation will not work here . Instead it is advised to
> configure un-numbered GRE interface and enable ISIS over it .
>
> Sample configuration :-
> *****************************
> On router 2
> ~~~~~~~~~~~
> interface Tunnel0
> ip unnumbered Serial2/0
> ip router isis
> tunnel source Serial2/0
> tunnel destination 167.1.123.1
> !
> interface Tunnel1
> ip unnumbered Serial2/0
> ip router isis
> tunnel source Serial2/0
> tunnel destination 167.1.123.3
> !
> router isis
> passive-interface Serial2/0
> is-type level-2-only
> !
>
> On R1 and R3
> ~~~~~~~~~~
>
> interface Tunnel0
> ip unnumbered Serial2/0
> ip router isis
> tunnel source Serial2/0
> tunnel destination 167.1.123.2
> !
> router isis
> passive-interface Serial2/0
> is-type level-2-only
> ********************************
>
> Design Note : ISIS do not advertise prefix that belong to un-numbered
> interface . In order to advertise NBMA subnet , you must add passive
> interface command for serial interface that is connected frame Relay
network
> under "router isis" command .
>
> Hope this helps .
>
> Thanks and Regards
> Arun
>
> ----- Original Message -----
> From: "Andrew Lissitz (alissitz)" <alissitz@cisco.com>
> To: "Arun Arumuganainar" <aarumuga@hotmail.com>; "Paresh Khatri"
> <Paresh.Khatri@aapt.com.au>; <comserv@groupstudy.com>;
> <ccielab@groupstudy.com>
> Sent: Tuesday, December 13, 2005 11:35 AM
> Subject: RE: ISIS - set-attached-bit and set-overload-bit
>
>
> > Ok, I got this working once I put a different L2 area on an adjacent
> > router. Thanks Arun for the tip, previously my lab did not have any
> > other L2 areas and thus ISIS did not create the default router as
> > expected. Once I added a different ISIS area, I now see the default
> > route generated.
> >
> > A follow up question: How do I determine which router is the DIS router
> > on a multi-access interface? In my case I was using serial multipoint
> > interfaces and realized that I needed the hub to be the DIS. Once I
> > configured this on the hub router, I had complete routing tables on all
> > remote routers.
> >
> > Thanks Arun and Group!
> >
> >
> >
> > ________________________________
> >
> > From: Andrew Lissitz (alissitz)
> > Sent: Monday, December 12, 2005 12:21 PM
> > To: 'Arun Arumuganainar'; Paresh Khatri; comserv@groupstudy.com;
> > ccielab@groupstudy.com
> > Subject: RE: ISIS - set-attached-bit and set-overload-bit
> >
> >
> > My L2 router did not have a L2 neighbor in another area. Perhaps this
> > is why I could not lab this? More answers in line ... in line -->
> > <Andrew>
> >
> >
> >
> > ________________________________
> >
> > From: Arun Arumuganainar [mailto:aarumuga@hotmail.com]
> > Sent: Monday, December 12, 2005 12:08 PM
> > To: Andrew Lissitz (alissitz); Paresh Khatri; comserv@groupstudy.com;
> > ccielab@groupstudy.com
> > Subject: Re: ISIS - set-attached-bit and set-overload-bit
> >
> >
> > Hi Andrew ,
> >
> > My comments inline .
> >
> > Thanks and Regards
> > Arun
> > ----- Original Message -----
> > From: "Andrew Lissitz (alissitz)" <alissitz@cisco.com
> > <mailto:alissitz@cisco.com> >
> > To: "Arun Arumuganainar" <aarumuga@hotmail.com
> > <mailto:aarumuga@hotmail.com> >; "Paresh Khatri"
> > <Paresh.Khatri@aapt.com.au <mailto:Paresh.Khatri@aapt.com.au> >;
> > <comserv@groupstudy.com <mailto:comserv@groupstudy.com> >;
> > <ccielab@groupstudy.com <mailto:ccielab@groupstudy.com> >
> > Sent: Monday, December 12, 2005 8:52 PM
> > Subject: RE: ISIS - set-attached-bit and set-overload-bit
> >
> >
> >
> > Hey Guys,
> >
> > Arun ... Nemeste, you rock man!
> >
> > I tried to use this in order to create default route on L1 routers. I
> > do not have configs with me, but the L1 routers saw routes from all
> > routers but no default route was in the routing table.
> >
> > [Arun]
> >
> > Could you explain me bit more . What do you mean create a default-route
> > on L1 routers ???
> >
> > <Andrew> - I was setting the attached bit on the L2 router and hoping to
> > see a default route on the L1 routers
> >
> > Actually there two methods for creating default route .
> >
> > Method 1 : setting the ATT bit
> >
> > This is done by default and no configuration is needed . But only thing
> > that is needed is to have L2 Neighbor that belongs to different area .
> >
> > By the way can you me provide your topology details in case your L1/L2
> > router is not able to inject default route to L1 routers .
> >
> > <Andrew> - I had one router as core and two remotes in L1 only.
> >
> > Method 2 : default-information-originate command .
> >
> > This will work independent of your topology .But you should remember
> > default-information will originate only L2-default . For generating
> > L1-default you need special configuration ( route-map needs to be
> > configured ) !!! Skeleton configuration is given below .
> >
> > ******************************************
> > !
> > route-map level1-default permit 10
> > set level level-1
> > !
> > !
> > Router isis
> > default-information originate route-map level1-default
> > !
> > ******************************************
> >
> > Note : If both methods are used to generate the default , Method 2 will
> > be preferred over Method 1 .
> >
> > <Andrew> - Thanks for the configs!
> >
> > [Arun]
> >
> > Here is what my thoughts are for this:
> >
> > You are using ISIS for IGP, you are asked to configure peer stub router
> > as L1 only. You are not allowed to use static default or default
> > information commands. Can this method work for this remote router to
> > receive a default route? This seems like a good method right?
> >
> > [Arun]
> >
> > "set-attached-bit" does not alter basic characteristic of L1-default
> > routing . It only adds more constraints to it To generate L1-Default by
> > setting ATT bit , what you need, is the visibility of atleast one L2
> > router that belongs to different area
> >
> > ***Hence the conclusion is ,this method will work only if your topology
> > permits***.
> >
> > [Arun ]
> >
> >
> > Perhaps this is good practice for the core router? In the lab there
> > will likely be some redistribution point between multiple routing
> > domains. This would be good, any comments on this idea?
> >
> > [Arun]
> >
> > One Caution on Multiprotocol scenarios.
> >
> > Just be careful about this in Multi-protocol scenario . EIGRP is a real
> > villain here !!! Whenever you configure auto summary( default in EIGRP )
> > , then EIGRP generates a static default route to Null0 . The main point
> > of contention is that EIGRP default has got an admin distance very much
> > lower that any other routing protocol . So even though default route is
> > generated in ISIS it may not get installed Such scenarios more
> > configurations are need to correct it . Some of techniques you can
> > employ are as follows .
> >
> > 1) Manually increase the admin distance for EIGRP .
> > 2) Redistribute L2 routes in to L1 . By this way you will inject more
> > specific route in to L1 routing . Hence Black holing may not happen .
> >
> > <Andrew> - EIGRP auto-summary ... I can not think of a time to use
> > this... Did you mean using the configuring a EIGRP summary on an
> > interface? Also, if EIGRP has a default in the routing table, and the
> > ISIS default does not get installed, it will still advertise it out to
> > ISIS neighbors?
> >
> > [Arun ]
> >
> >
> > -----Original Message-----
> > From: Arun Arumuganainar [mailto:aarumuga@hotmail.com]
> > Sent: Monday, December 12, 2005 10:13 AM
> > To: Paresh Khatri; Andrew Lissitz (alissitz); comserv@groupstudy.com
> > <mailto:comserv@groupstudy.com> ;
> > ccielab@groupstudy.com <mailto:ccielab@groupstudy.com>
> > Subject: Re: ISIS - set-attached-bit and set-overload-bit
> >
> > Hi Paresh ,
> >
> > I think to understand this feature we need some good understanding of
> > Integrated ISIS !!!
> >
> > Let me explain :
> >
> > Default Behavior in ISIS
> > ~~~~~~~~~~~~~~~~~~
> > ISIS says that a L1L2 router should set the attached-bit in its L1 LSP
> > when that router thinks it is attached to the L2 backbone. Currently IOS
> > uses a simple algorithm to determine if it is attached. This algorithm
> > says if a
> > L1L2 router during an SPF computation sees other area addresses, then it
> > thinks it is attached to the L2 backbone and hence it should set att
> > bit.
> >
> > Problem with Default Behavior
> > ~~~~~~~~~~~~~~~~~~~~~~
> > Often this is good enough. However, in some network designs it can
> > happen that L1L2 routers in two different areas get separated from the
> > L2 backbone.
> > Because they see each others area, they still think they are attached to
> > the
> > L2 backbone. This might cause L1-only routers to send traffic for the
> > backbone to the wrong L1L2 routers.
> >
> > Cisco Solution
> > ~~~~~~~~~~~
> > To solve this problem , IOS gives network administrators better control
> > over, when a L1L2 router should decide,it is attached to the L2
> > backbone.
> > Here Admistrator has the option of setting the area that should be
> > visible in order to set the ATT bit
> >
> > Note : Irrespective of IP or CLNS, area address in ISIS is represented
> > by CLNS address format ( We use " net " under "config-router" prompt for
> > specifying area ).
> >
> > Hence route-map for "set-attached-bit " should match area address( an
> > CLNS address ) that has to visible in order to set the att bit .This
> > command is applicable to both CLNS and IP routing
> >
> > By the way , command reference is right . Route map will infact refer to
> > CLNS routing table for the presence or absence of matching criteria
> > FYI :
> > To view clns route use "SHOW CLNS ROUTE" on the router in which ISIS is
> > configured .
> >
> > Hope this helps .
> >
> > Thanks and Regards
> > Arun
> > ----- Original Message -----
> > From: "Paresh Khatri" <Paresh.Khatri@aapt.com.au
> > <mailto:Paresh.Khatri@aapt.com.au> >
> > To: "Arun Arumuganainar" <aarumuga@hotmail.com
> > <mailto:aarumuga@hotmail.com> >; "Andrew Lissitz
> > (alissitz)"
> > <alissitz@cisco.com <mailto:alissitz@cisco.com> >;
> > <comserv@groupstudy.com <mailto:comserv@groupstudy.com> >;
> > <ccielab@groupstudy.com <mailto:ccielab@groupstudy.com> >
> > Sent: Monday, December 12, 2005 4:09 PM
> > Subject: RE: ISIS - set-attached-bit and set-overload-bit
> >
> >
> > Actually Arun, I still think my initial post was correct...the command
> > reference for this feature indicates that the route-map can only be used
> > for matching on CLNS routes, and not IP routes.
> >
> > Here's a quote from it:
> >
> > "The route map can specify one or more CLNS routes. If at least one of
> > the match address route-map clauses matches a route in the L2 CLNS
> > routing table, and if all other requirements for setting the
> > attached-bit are met, the L1L2 router will continue to set the
> > attached-bit in its L1 LSP. If the requirements are not met or no match
> > address route-map clauses match a route in the L2 CLNS routing table,
> > the attached-bit will not be set."
> >
> > Regards,
> >
> > Paresh.
> >
> > -----Original Message-----
> > From: Arun Arumuganainar [mailto:aarumuga@hotmail.com]
> > Sent: Mon 12/12/2005 9:16 PM
> > To: Andrew Lissitz (alissitz); Paresh Khatri; comserv@groupstudy.com
> > <mailto:comserv@groupstudy.com> ;
> > ccielab@groupstudy.com <mailto:ccielab@groupstudy.com>
> > Cc:
> > Subject: Re: ISIS - set-attached-bit and set-overload-bit Hi Andrew ,
> >
> > Paresh is almost correct .We do not have full flexibility for setting
> > the ATT bit .
> >
> > But times are changing and features gets added up !!! Check this out !!!
> >
> > This is one of the feature that are used to optimize L1-Routing . After
> > introduction of this feature , network admins can influence ATT bit
> > setting using "ser-attached-bit Route-map " command .
> >
> > FYI : You should be using 12.2(4)T or Later .
> >
> > Pls. refer to the CCO Link
> > http://www.cisco.com/en/US/products/ps6599/products_white_paper09186a008
> > <http://www.cisco.com/en/US/products/ps6599/products_white_paper09186a00
> > 8>
> > 04fa
> > 7a0.shtml
> >
> > or In case you have access Cisco Bug tracking tool . You can also check
> > out Bug ID : CSCdp64489
> >
> > Pls. Note : Even after this feature we can arbitarly set att bit in IOS
> > .
> > Your L1/L2 router still need to have visibility to atleast one area
> > other than its own !!!
> >
> > Thanks and Regards
> > Arun
> >
> > ----- Original Message -----
> > From: "Andrew Lissitz (alissitz)" <alissitz@cisco.com
> > <mailto:alissitz@cisco.com> >
> > To: "Paresh Khatri" <Paresh.Khatri@aapt.com.au
> > <mailto:Paresh.Khatri@aapt.com.au> >;
> > <comserv@groupstudy.com <mailto:comserv@groupstudy.com> >;
> > <ccielab@groupstudy.com <mailto:ccielab@groupstudy.com> >
> > Sent: Thursday, December 08, 2005 10:56 AM
> > Subject: RE: ISIS - set-attached-bit and set-overload-bit
> >
> >
> > > Paresh you rock! I am going to try this now, thanks
> > >
> > >
> > > -----Original Message-----
> > > From: Paresh Khatri [mailto:Paresh.Khatri@aapt.com.au]
> > > Sent: Thursday, December 08, 2005 12:23 AM
> > > To: Andrew Lissitz (alissitz); comserv@groupstudy.com
> > <mailto:comserv@groupstudy.com> ;
> > ccielab@groupstudy.com <mailto:ccielab@groupstudy.com>
> > > Subject: RE: ISIS - set-attached-bit and set-overload-bit
> > >
> > > Hi Andrew,
> > >
> > > I don't believe that you can use the 'set-attached-bit' command when
> > > using
> > ISIS for routing IP; while the ATT bit is also used by IP, you can only
> > set it via this command when routing CLNS via ISIS.
> > >
> > > As for the second command, one possible way a question could require
> > > you
> > to use this is: configure your interior routers so that they do not
> > advertise themselves as available for transit routing until BGP has
> > converged on these routers. Or: configure your interior routers so that
> > they do advertise themselves as available for transit routing until 2
> > minutes after the IGP routing process has started.
> > >
> > > Here's my little summary of how you can use the set-overload-bit
> > command:
> > >
> > > set-overload-bit
> > > ' immediately and unconditionally sets the overload bit
> > >
> > > set-overload-bit on-startup <seconds>
> > > ' sets the overload bit on startup for the specified number of seconds
> > (from 5 to 86400)
> > >
> > > set-overload-bit on-startup <seconds> suppress interlevel ' sets the
> > > overload bit on startup for the specified number of seconds
> > (from 5 to 86400). Suppresses advertisement of any inter-level routes
> > while the overload bit is set.
> > >
> > > set-overload-bit on-startup <seconds> suppress external ' sets the
> > > overload bit on startup for the specified number of seconds
> > (from 5 to 86400). Suppresses advertisement of any redistributed routes
> > while the overload bit is set.
> > >
> > > set-overload-bit on-startup <seconds> suppress interlevel external '
> > > sets the overload bit on startup for the specified number of seconds
> > (from 5 to 86400). Suppresses advertisement of any inter-level or
> > external routes while the overload bit is set.
> > >
> > > set-overload-bit on-startup wait-for-bgp ' sets the overload bit on
> > > startup. It's cleared on receiving a signal
> > from BGP or after 10 minutes, whichever comes first.
> > >
> > > set-overload-bit on-startup wait-for-bgp suppress interlevel ' sets
> > > the overload bit on startup. It's cleared on receiving a signal
> > from BGP or after 10 minutes, whichever comes first. Suppresses
> > advertisement of any inter-level routes while the overload bit is set.
> > >
> > > set-overload-bit on-startup wait-for-bgp suppress external ' sets the
> > > overload bit on startup. It's cleared on receiving a signal
> > from BGP or after 10 minutes, whichever comes first. Suppresses
> > advertisement of any redistributed routes while the overload bit is set.
> > >
> > > set-overload-bit on-startup wait-for-bgp suppress interlevel external
> > > ' sets the overload bit on startup. It's cleared on receiving a
> > > signal
> > from BGP or after 10 minutes, whichever comes first. Suppresses
> > advertisement of any inter-level or external routes while the overload
> > bit is set.
> > >
> > > set-overload-bit suppress interlevel
> > > ' immediately and unconditionally sets the overload bit. Suppresses
> > advertisement of any inter-level routes while the overload bit is set.
> > >
> > > set-overload-bit suppress external
> > > ' immediately and unconditionally sets the overload bit. Suppresses
> > advertisement of any external routes while the overload bit is set.
> > >
> > > set-overload-bit suppress interlevel external ' immediately and
> > > unconditionally sets the overload bit. Suppresses
> > advertisement of any inter-level or redistributed routes while the
> > overload bit is set.
> > >
> > > HTH,
> > > Paresh.
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com <mailto:nobody@groupstudy.com>
> > [mailto:nobody@groupstudy.com]On Behalf Of
> > Andrew Lissitz (alissitz)
> > > Sent: Thursday, 08 December 2005 03:01 PM
> > > To: comserv@groupstudy.com <mailto:comserv@groupstudy.com> ;
> > ccielab@groupstudy.com <mailto:ccielab@groupstudy.com>
> > > Subject: ISIS - set-attached-bit and set-overload-bit
> > >
> > >
> > > Hello group,
> > >
> > > I am trying to think of a scenario / question that may cause me to
> > > think
> > of this feature.
> > >
> > > pe1(config)#router isis
> > > pe1(config-router)#?
> > > set-attached-bit Conditionally advertise us as attached to L2
> > > set-overload-bit Signal other routers not to use us in SPF
> > > pe1(config-router)#
> > >
> > > My lab:
> > >
> > > R1 <---> R2 (My lab follows the 'KISS' design guide)
> > >
> > > Has anyone used these features and or can think of a question /
> > > scenario
> > that would cause me to look at this feature for the solution. I am
> > really trying to think of how a question / scenario could be written.
> > > Kindest regards group,
> > >
> > > Andrew
> > >
> > > ______________________________________________________________________
> > > _ Subscription information may be found at:
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> > <http://www.groupstudy.com/list/CCIELab.html>
> > >
> > >
> > > This communication, including any attachments, is confidential. If you
> >
> > > are
> > not the intended recipient, you should not read it - please contact me
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> > >
> > > ______________________________________________________________________
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> >
> >
> >
> >
> >
> > This communication, including any attachments, is confidential. If you
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