Re: Re : MAC Address to IP Address conversion
Another trick that works to make sure you get everything is to first clear the arp cache (clear arp-cache) and then ping the broadcast address (either the all zeroes broadcast, or if you just want one net, then ping that network's broadcast, i.e. if your net is 209.149.135.0/24, then ping 209.149.135.255). Every device that falls in that range (barring any subnet masking mistakes), and if all machines are powered on will answer the router's pings. Now do your "show arp", you'll get a very accurate mac to ip address table. Amit Gupta (EHPT) IS-IT wrote: [EMAIL PROTECTED]"> Got the list from my Router's ARP cache -Original Message-From: Amit Gupta (EHPT) IS-IT [SMTP:[EMAIL PROTECTED]]Sent: Sunday, November 26, 2000 3:19 PMTo:'[EMAIL PROTECTED]'Subject: Re : MAC Address to IP Address conversionHello All,I am looking for some sniffer software that could show me a list of MAC Address to IP Address mapping of my netwo! rk.I checked with the trial copies of CNAPro and Sniffer PRO would could not find the functionality.Can anyone suggest.Thanks & RegardsAmit _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Fw: BGP on the Brain - Design Issue
Maybe I can help with this.
BGP doesn't do load balancing in the traditional sense of the word. The
only time you'll see a router have two BGP learned routes to the same
network is when that router has two connections to the same ISP and you
have configured the command "maximum-paths 2" under the BGP routing
process. And I venture to say that you'll never see a BGP router doing
"per-packet" load balancing. Not in the real world. Per-packet load
balancing requires process switching which drags performance of the router
down.
Typically, to make sure that both links get utilized, the edge BGP routers
will advertise a default route into the IGP and from there it is up to the
IGP to make the best routing decision. For instance:
--Router1Router2--
Router3-Router4--
Both Router1 and Router4 are injecting 0.0.0.0 into OSPF. Now Router2 will
prefer the 0.0.0.0 coming from Router1 because it has a lower OSPF Metric
than the one coming from Router4. (and the inverse is true of Router3).
Of course, you as the Design Engineer have every option open. You can
influence all the traffic to go one way or another. But you have to know
the network and the traffic patterns very well before you start. You can
set metrics to influence path selection. Or you can use Route Maps (Policy
routing). You can have Router2 Send all HTTP traffic over Router1's
default link, and all other traffic over Router4's link.
You can customize BGP to suit your needs, but the difference between it and
other Routing Protocols is that you have to decide the direction, you can't
leave it up to BGP to pick the best path (like you would with an IGP).
Hope this helps.
Gary Frye
Internetwork Engineer - CCNP,CCDP,CNE,MCSE
Charlotte, NC 28262
Phone: (704) 427-0564
Pager: (800) 504-8567
Cell: (704) 502-7921
Fax: (704) 590-7477
Email: [EMAIL PROTECTED]
WWW: http://www.firstunion.com
"Because we're dealing with Engineers and not Mathematician, 'infinity'
turns out to be 16."
-Radia Perlman on IP RIP
-- Forwarded by Gary Frye/AO/USR/FTU on 09/05/2000
08:18 AM ---
[EMAIL PROTECTED] on 09/04/2000 10:16:55 PM
To: Gary Frye/AO/USR/FTU@FTU
cc:
Subject: Fw: BGP on the Brain - Design Issue
- Original Message -
From: "Chuck Larrieu" <[EMAIL PROTECTED]>
To: "Cisco Mail List" <[EMAIL PROTECTED]>
Sent: Monday, September 04, 2000 12:38 AM
Subject: BGP on the Brain - Design Issue
> The question has been posted here once or twice. It goes something like
> this. "How do I use BGP to load balance between two ISP's?"
>
> I'm starting to get into BGP in earnest in preparation for the CCIE
written.
> And I have something of a fascination with design issues. Let me see if I
> can sort out my thoughts. Please comment where you can.
>
> 1) First of all, the load balancing issue. BGP itself has no mechanism
> within it for load balancing of any kind, whether that be per packet or
per
> destination.
>
> 2) If one could use BGP for per packet "load balancing" then one is in the
> position of doing suboptimal routing in many cases. For example, if I am
> connected to AS101 and AS202, and I want to go to a particular e-commerce
> site, and it is 5 hops via AS101 and 20 hops via AS202 then I have created
> problems for higher layers due to issues with packets arriving out of
> sequence. Potentially I have hurt my performance, maybe even killed it.
>
> 3) If one were to use BGP for per destination "load balancing" isn't is
> possible that the optimum path for all, or at least most, destinations
might
> still lie through one AS or the other? I mean, there is no way to predict
> this, is there?
>
> 4) So from a design perspective, assuming Mr. Pointy-Hair insists on "load
> balancing between two ISP's" the setup most likely would be something like
> this:
> Inside_router-BGP_router_1ISP_1
> |--BGP_Router_2---ISP_2
>
> and doing something like setting up two 0.0.0.0 routes, one to each BGP
> router, and letting the inside router to the "load balancing"
Re: CCIE review....
1). HDLC will count bad frames and drop them. It's up to the hosts to retransmit. 2). LEC could fail to find a LECS because it isn't configured with the LECS' VCI/VPI, and the LECS isn't operating on a well-known VCI/VPI (there are other reasons, but that is the most prominent) 3). The * means that this route entry is the last resort route. 4.) No need to worry about STUN. Cisco has all but dropped interest in it and you won't see it on any tests (not even the CCIE written/lab). In its place, be sure you know the hell out of DSLSw+ and RSRB. garyf - Original Message - From: "Henrique Issamu Terada" <[EMAIL PROTECTED]> To: "'Schmendrick Dawes'" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Sunday, May 07, 2000 6:04 PM Subject: RES: CCIE review > Answering just one question. > > 1) Who handles retransmition is Layer 4 , through TCP flow control. >I'm not sure if there is also a retransmition in HDLC, but I'm sure that > there's no one in Frame Relay , and there is in X25. > > Henrique > > - Mensagem original - > De: Schmendrick Dawes [SMTP:[EMAIL PROTECTED]] > Enviada em: Sunday, May 07, 2000 2:54 AM > Para: [EMAIL PROTECTED] > Assunto: CCIE review > > While doing a scan of my review outline, I realized > there were several points I was unclear on in my weak > areas > > 1)Who handles retransmission between two ethernet > hosts > over HDLC serial links if there is a line hit? Router > or hosts? > > 2)What are some typical reasons that a Lec could fail > to find a lecs in ATM LANE? > > 3)What does a star (asterisk *) next to the S mean in > a routing table? > > 4)How does IPX queuing work with STUN? > > Any help on any of these weak areas would be > appreciated! > Thanks > > > > __ > Do You Yahoo!? > Send instant messages & get email alerts with Yahoo! Messenger. > http://im.yahoo.com/ > > ___ > FAQ, list archives, and subscription info: http://www.groupstudy.com > Posting Guidelines: http://www.groupstudy.com/list/guide.html > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: [Fwd: Morning]
It could just be my two cents worth, but I was under the impression that split-horizon only affected distance-vector routing protocols and that link-state protocols with their more sophisticated LSA's gives the router a better view of the entire internetwork, and so split-horizon isn't necessary and doesn't apply. I know that EIGRP is a hybrid routing protocol... but it is typically considered a link-state one. Just stating what I think the explanation could be. garyf CCNP - Original Message - From: "David Wolsefer" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Wednesday, June 07, 2000 10:25 AM Subject: FW: [Fwd: Morning] > Scott, it depends. Let me clarify and see if this helps. You only need to > turn off split horizon with eigrp on the hub router if and only if you are > using a point-to-multipoint subinterface on the hub router. If all your > interfaces are point-to-point (which they probably should be), then you will > not have a split-horizon problem. Let me know if you have further questions > and we can clear them up. BTW, you do not need to turn off split horizon on > point-to-point subinterfaces, only multipoint subinterfaces. > > Regards, > > David Wolsefer, CCIE #5858 > > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of > Scott Livingston > Sent: Tuesday, June 06, 2000 1:16 PM > To: [EMAIL PROTECTED] > Subject: [Fwd: Morning] > > > can someone help out here please? THANKS! > subject: >Morning >Date: >Tue, 06 Jun 2000 07:50:00 -0500 > From: >Scott Livinston <[EMAIL PROTECTED]> > To: >[EMAIL PROTECTED], Jon Helmer <[EMAIL PROTECTED]> > > > > > > This is reference to Mr. David Wosefer's white paper about Frame Relay.. > > David, > > We are currently running a small F.R. network over here and something > you wrote contradicted what we currently have in operation.. Currently > we have a hub and spoke topology, 3 spokes to be exact... we are an IP, > partial meshed network running subinterfaces and EIGRP.. You mentioned > in your paper that you need to turn off ip split-horizon on the > subinterfaces if the spokes are to know about the other spokes > networks.. Well in our case we don't have ip split horizons turned off > and the spokes know about all other spokes... How could this be? I had > my lead engineer look @ this and we both cant figure out this > discrepancy between what you published and what we are currently running > > over here... If you get some time could you please show me where i might > > be lost? Thanks for your help! > > -- > Scott M. Livingston > Network Engineer (CCNP) > 12851 Foster > Overland Park, KS 66213 > 800.888.7535 > 913.402.7844 x1056 > 913.814.7849 Fax > > "Make every swing as if it were your last" > -Gary Schroer > -- > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ask for help on DHCP
Yep, all you need is to configure the Helper address (ip helper-address [address]) command on Router1, and as long as Router1 has route to LAN3 (whether by static or routing protocol... and Router3 has route back to LAN1). See, Router1 will take the DHCP broadcasts and convert them into unicast packets and send them directed to LAN3. For the "address" argument in the command you can use the specific IP of the DHCP server or use the broadcast address for that network (192.168.100.255). garyf - Original Message - From: "Cai, Land" <[EMAIL PROTECTED]> To: "'Cisco (E-mail)'" <[EMAIL PROTECTED]> Sent: Sunday, June 04, 2000 8:52 PM Subject: ask for help on DHCP > Dear gang, > > I have the following situation. > > Ethernet LAN1Router1---Router2(TokenRing > LAN1)-Router3-Ethernet LAN3 > | > | > | > | > | > | > Router4 > Router4 > > > Let 's say Ethernet LAN1 has the ip segment 192.168.1.*/24, > Ethernet LAN3 has the IP segment 192.168.100.*/24, > I want the clients on Ethernet LAN1 can get ip address from > DHCP server located in Ethernet LAN3 automatically. Can I get it to > reality? I do only need to configure the IP helper address for Ethernet > interface on the router1, don't I? Or I need to configure something on > router1, 2, 3? > > Thanks in advance, > Cai, land > > > > > > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
