What exactly is an underrun and what are the possible causes for
FE underruns?
Thanks
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What does the global tag do when part of an ip route command?
ip route . global
Does this tag only have meaning when the ip route is being
used to add a route into a vrf?
Thanks
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I'm having some problems wit CEF and so enabled a number of CEF
debug commands (ip cef drops, events, received). I'm getting periodic
debug output which says "CEF: slow service". What does this mean?
Thanks
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Nope, but I am using VRFs.
Joseph Brunner wrote:
>
> are you running cef with NAT ?
>
> Joseph Brunner
> ASN 21572
> MortgageIT MITLending
> New York, NY 10038
> (212) 651 - 7695 Voice
> (212) 651 - 7795 Fax
>
> -----Original Message-
> From: bergenpe
Hi,
Wondering if anyone has been using ACLs to block or rate-limit
Kazaa/Morpheus
traffic. I'd be interested in how well this worked.
Thanks
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Hi,
I've got a router with a number of routes defined (connected interfaces,
route learned from OSPF, etc.) One of these routes is a default route.
When I do a "show ip route" for a network which has a specific routing
entry (ie non-default), I get back the expected routing information.
If I
AIC (American Internet Comp) made, among other things, a DHCP server
product.
Cisco bought AIC and repackaged the AIC DHCP server as CNR.
Ozzie Sutcliffe wrote:
>
> This guy also made site bulder for Novell way back when..1995 and he owned
> www.american.com then
> So Cisco got the site name
Suppose you have an edge router that has 10 or so connected subnets
and a default egress route. This box is not running a dynamic
routing protocol.
If one was to enable CEF on this box (over fast switching), would one
expect to see any/much performance improvement? This box does not
support dCE
Just a clarification. It is possible to have multiple subnets on
an interface and configure the DHCP server to assign IPs to any of
these scopes. No router address flip-flopping or other machinations are
required or needed.
As has been posted, the primary IP address on the interface is *usually
Hi Mike,
Responses inline:
> I understand the logic of tying the secondary scopes to the primary at ehe
> DHCP side, however if the giaddr always reflects the primary subnet, how
the
> the DHCP server ever know to hand out addrs from the other secondary
scopes?
On the DHCP server, one configure
There was a paper published by PacketDesign 1-2 years ago
which suggested that features like MPLS fast-reconvergence
were solving a problem which could be better done by getting
IGP protocols to re-converge faster. There was some discussion that
IGPs could be updated to support this (much bigger
Got some GSRs with some OC interfaces (engine 0) which connect to
our tier-1 where I've had to put in some inbound ACLs (SNMP filter,
etc.)
Since these are engine 0 cards, I've had to use Turbo ACLs. The line
card CPUs are running about 50-60% utilization.
If I need to add more ACLs to these
1) A loopback address is normally advertised by OSPF as a host route.
The command "ip ospf network point-to-point" enables one to specify
that the interface should be advertised as a subnet route. What are
the benefits for doing this?
2) Must a link cost be the same on for all routers that share
Hi Priscilla,
The use of the "ip ospf network point-to-point" as a mechanism
to enable one to advertise the loopback address as a subnet route
is from Doyle (Routing TCP/IP V1), page 417, footnote 9.
Priscilla Oppenheimer wrote:
>
> At 08:59 AM 3/4/02, bergenpeak wrote:
Is it possible to tag routes (via an IGP or BGP) and then perform
a policy route decision which in part does a check for this tag?
Specifically, the logic I'm looking for is a route-map which is
applied in the packet forwarding phase which will change the forwarding
behavior if the packet is for
I was somewhat surprised to see a Juniper box support cisco hdlc
encap on a POS interface. Didn't realize that other vendors supported
this standard. Which brings me to my question.
Is there any unique benefit to the specific encap (PPP, cisco HDLC)
used on a POS interface? Is there some tec
Hi Sam,
The shared vs non-shared issue DSL providers mention is somewhat
misleading. In any residential cable or DSL network, you will
have stat muxing. In a cable network, this happens on the HFC
network. In a DSL network, this happens at the Agg router (the
one that terminates all of those
I'm looking at an design where there's a hub-spoke network
based on 802.1q. Specifically, there will be a number of routers
connect back via FE/GE into a central router through an 802.1q
trunked interface. Each remote router will run OSPF and thus
should form an OSPF adjancency with the central
Some clarifications for this post:
* Just about every DOCSIS cable modem on the market operates as an
ethernet bridge. If one has residential HSD service from a cable
company and you "lease" the modem, then you have a bridging modem.
* While DOCSIS modems are bridging devices, they will not br
Hi John,
Cable companies often configure their provisioning (DHCP) severs
to verify that the incoming DHCP request is from a MAC which is
known.
Couple of things to try.
* Power cycle the CM and then have the PIX attempt to do DHCP.
Do you get a DHCP OFFER?
* After you power cycle the modem,
I'm reading through ACRC chapter 11 and have a couple of
questions. I expect these are pretty basic...
* On page 267-268 theres the comment that "Only a default static
route is automatically advertised". I'm not sure I understand
this-- does it mean that I don't need to enable redistribution
in
All DOCSIS modems will have MAC addresses and the modem
will use DHCP to get an IP address. The modem must be
able to get an IP address via DHCP as part of it's boot-up
sequence.
Some older modem technologies did not require the modem have
a MAC address. A proprietary protocol was used betwee
I'm trying to use the "set ip next-hop" feature in a route-map
and seeing some behavior I don't understand.
If I define the "ip next-hop" to be an IP address that's
not on an interface directly connected to the router performing
the route-map, the router does the recursive lookup and
forwards the
What exactly does this do?
Thanks
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Report misconduct and Nondisclosure violatio
ethernet on the local router?
> this should send all traffic for the destination network out
> that interface regardless. it makes your routing table look
> like everything is directly connected but at least it works
> for ip route staments..
>
> ""bergenpeak""
00:00:0C:05:3E:80
>Source: 00:00:0C:05:3E:80
>Protocol Type:0x9000
>Packet Data: 46 bytes (all zeros)
>
> The frame really does go out on the network, despite it being addressed to
> the sender. So the router can judge its ability to send and receive.
>
> Pri
Simple question I'd guess. When is the motd banner displayed
and when is the login banner displayed? I've configured both
on a router and both seem to be displayed when I login via a vty
or console. Is there a time when only one of these are displayed,
and if so, when?
Thanks
Message Post
Question from Chappel's book (ICRC, Chapter 11, page 269). Is
generic as well. About IPX framing options. ICRC shows four
different ways to frame IPX on ethernet:
Cisco name frame format
- -
novell-ether802.3 IPX
sap 802.3 802.2_LLC IPX
arpaet
I'm working through the different ways one can configure CHAP
authentication between two routers over a PPP serial link.
If I configure ppp encap and ppp chap authentication and both sides
of the link and use the global:
username password
for identification, the link comes up and IP
"sent-username" is not an option for me under ppp chap. My
options at "ppp chap" are "hostname", "password", "wait", and
"refuse".
Thanks
"McCallum, Robert" wrote:
>
> what about ppp chap sent-username ?
>
> -
e info/comments.
Cisco Breaker wrote:
>
> Your only choice is to use global username other router and password the
> sama as your router they must be identical on both sides.
>
> ""bergenpeak"" wrote in message
> [EMAIL PROTECTED]">news:[EMAIL P
get to work as
> advertised, post your results, and I'll try and see what happens!
>
> -Stefan
>
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
> bergenpeak
> Sent: Wednesday, January 09, 2002 10:26 AM
> To: [EMAIL P
What's the difference between these two protocols?
Besides some cisco switch equipment, what other vendors
support the DEC form of spanning tree?
Thanks
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In 802.1d spanning tree, the BPDU contains a number of fields
including the "Port ID". THis is a two byte value where one
octet contains a priority value and the second byte contains
a value assigned to each port.
For some of the higher density switches, (55xx, 65xx), one can
have more then 256
When a cat1900 is configured with the port-secure command, it appears
that unauthorized frames will trigger an "address violation action".
How does one change and view the current action setting for address
violations?
It would seem that address violations only occur on frames received
on the po
Is it possible to establish a DISL trunk between a cisco switch
and a non-cisco switch?
If so, how would one configure the port on the cisco switch side?
Thanks
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quantity, and there's no expectations of uniqueness of
the "port number" octet, than all should work as expected.
Thanks
Priscilla Oppenheimer wrote:
>
> Hello Bergenpeak,
>
> Please see some comments below..
>
> At 11:11 AM 1/21/02, bergenpeak wrote:
> >
Trying to get more information on VACLs. ANyone know of a URL white
papaer on VACLs?
What switches or images support VACLs?
THanks
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t; the other end. Nmap, among many other tools, has options to send fragmented
> packets in a variety of ways. Check out http://www.insecure.org for some
> informative white papers on OS fingerprinting.
>
> - Sean
>
> -Original Message-
> From: bergenpeak [mailto:[EMAIL
In Europe, a PRI carries 30B and one D channels. Each operates at
64kb/s.
The overall PRI bandwidth is 2.048 Mb/s. 31 channels at 64 kb/s
is 64kbps less than 2.048Mb/s.
What's the 32nd 64kbps channel used for?
Thanks
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Is the MD5 encryption used when one enables the "service
password-encryption"
before entering the vty password?
What encryption mechanism is used when a password is entered as type 7?
Thanks
"Henry D." wrote:
>
> It's not possible to use MD5 on vty's.
> I suppose the reason would be that MD5
Sort of related question. When you SWIP the /24 to your customer,
who is responsible for the address utilization? Said differently,
can you get more addresses if you show that your /19 minus the
customer /24 has the right level of utilization? Or, must the
overall /19, including the customer's
Scanning the exam topics, specifically the second to last bullet item:
Optical Networking Designs
Describe the scalability issues of using OSPF and IS-IS as interior
gateway
protocols in a service provider network and list solutions for each
What do IGPs have to do with optical network de
weight is not an attribute carried in BGP. It's a cisco
specific mechanism that is local to a router, and when
configured, may impact the BGP path selection on that router.
lee wooi keat wrote:
>
> All,
>
> I'm preparing CCIE written exam and encounter some tricky questions in
> exercise. Woul
I'll guess and say this is an accident prevention mechanism. Suppose
you have two egress points and each advertises a default. If the link
from one of these egress devices to its peer fails, might the eBGP
session
remain up, but follow the default through the other egress location?
You wouldn't w
Not necessarily. Recall that with eBGP sessions it is typical
to peer with the physical address. There are times when you
want to use the lo0 for eBGP (two parallel links, etc.) but
you'll need to specify both ebgp_multihop and define a route
to the peer's loopback.
Priscilla Oppenheimer wr
Not sure what engine line cards you're running on your GSRs, but I've
run into several a problems with ACLs on the GSR platform. It's not
until you get to the E3 ISE or better LC where ACLs are handled
reasonably.
Three problems from memory:
* E0 line cards run the ACLs off the LC CPU and not A
Not sure what engine line cards you're running on your GSRs, but I've
run into several a problems with ACLs on the GSR platform. It's not
until you get to the E3 ISE or better LC where ACLs are handled
reasonably.
Three problems from memory:
* E0 line cards run the ACLs off the LC CPU and not A
Related question to the above thread.
As discussed, each routing protocol will maintain its list of prefixes
that it knows about. A route selection process runs that considers the
routes from each routing process and puts the "best" into the routing
table. (best being defined by the route sel
Trying to understand OSPF behavior when generating a default
route.
If I do a "default-information originate" in OSPF, I see a
E2 0/0 route on all other OSPF routers. Ok, I understand this.
If I instead define a static default route
"ip route 0.0.0.0 0.0.0.0 a.b.c.d" and then in my OSPF
setup
network. But, when I took of that statement
> and added the "restribute static subnets" statement, it propagated
> successfully.
>
> Did you add a static default route (ip route 0.0.0.0 .0.0.0.0 a.b.c.d)
> before you tried the "default-information originate" state
I'm considering running slb on a 7609 to load balance
across a number of DNS servers.
Wondering when others have done this if this has worked
well (no bugs, good performance, etc.). Would also be
interested in what MIBs or traps where used for monitoring
slb operation and performance
Thanks
I've got a 3640 sitting in an RDC connected to a number of
sun servers. I'm running TACACS on the 3640 to authenticate
people who telnet directly to the 3640.
I've configured telnet pass through so that one can telnet
through the 3640 directly to a console port (telnet 3640-lo0 port).
This allow
I've got a rather large OSPF area 0 network with no non-zero
areas. This network will continue to grow both in number of
network elements and number of subnets on these routers.
What commands, and specifically, what information provided by
these commands, will give me insight as to whether thes
Looking at the administrative distance values for the different
routing mechanisms.
Why would eBGP have a lower admin distance for a route than
if learned via an IGP (like OSPF or ISIS)? Why wouldn't
the default behavior be to prefer routes learned from the local
IGP rather than via eBGP?
THan
between 2 routers eth
> [7:55457]" (Mar 4, 9:46am)
> X-Mailer: Mail User's Shell (7.2.5 10/14/92)
> To: "bergenpeak" , [EMAIL PROTECTED]
> Subject: Re: can I use a /31 subnet to the link between 2 routers eth
> [7:55457]
> Cc:
>
> On Mar 4, 9:46am, "
Sorry for the OT post. Figured I'd float this here and see if
any one might be able to help.
Does anyone really know where the 50 ms SONET detect/fail-over time
comes from?
I've heard many answers, but none seem to be verifiable. I'm looking
for pointers to docs which explain where or what drov
generic standards doc or other SONET Bellcore GR
> docs relating to switching times and the equivalent
> SDH ITU-T standards (which I am not sure what it is).
> On the SDH side you may want to start with ITU-T
> G.783.
>
> Hope this helps
>
> pb
>
>
> --- bergenpeak
Is it necessary, when doing a redist RIP in an OSPF router process,
to specify a metric?
I've heard that a metric is required and if not specified, OSPF will
not advertise the RIP routes. In my testing, RIP routes being redist
into OSPF even without an explicit metric do show up in the routing
ta
I'm using an NSSA in some sites and want to prevent type 7 LSAs
in these sites from being converted into type 5 LSAs and being
injected into area 0.
It appears this is possible using the summary-address command.
Specifically, I'm considering doing the following in the ABR:
summary-address
I've got a number of different subnets on an OSPF ASBR that I would
like to OSPF tag and advertise according to function.
Assume these networks are directly connected to the ASBR and that
a "redistribute connected subnets" is being used to make these
subnets type 5 (type 7s in an NSSA).
Besides
Is it possible to take tag values carried in OSPF external route
advertisements and automatically map them into the community
attribute of the respective BGP advertisement?
Consider a router running both OSPF and BGP. In the BGP config,
there's a redistribute from OSPF into BGP. Assume that only
I'm considering enabling some features on a E0 GSR line
card. I'm going to monitor the line card CPU utilization
in order to track the impact the features have on the LC.
Does anyone have any general rules of thumb (or reference
document) that provides guidelines on how far, utilization
wise, a l
Suppose I have several routers making up an iBGP mesh. Lets
suppose I have two routers (R1 and R2) which are advertising the same
set of networks: N1, N2, ... Nk.
OSPF is running underneath BGP (assume area 0). All of the N
networks are being advertised with a next-hop set to the respective
lo
y unlikely and this seems like this would
prevent
the loop problem. It would seem this might provide prefix load
balancing,
but does not install two routes in the routing table for N1?
The Long and Winding Road wrote:
>
> a couple of things - in line below
>
> "&quo
Anyone know why one can run only a single RIP process on a cisco
router?
Thanks
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Anyone have a document which details to how public peering is typically
done
at an ethernet-based peering location?
I had envisioned that one dropped a router, had a GE pulled into the
peering
location, got an IP address from a large block (ie /24) from the peering
center,
and started peering with
Interesting question. Some thoughts from someone that does have a PhD
in CS (dissertation in networking, a dozen or so publications, a handful
in IEEE journals). I initially went into gradual school to teach and do
research, but after spending two summers during grad school as an intern
in indust
Reading Doyle's V1 book. Page 195 mentions that when an update with a
hop count higher than that in the routing table is received for a route,
the route will go into holddown for 180 [sic] seconds (three update
periods).
In the cisco page (below) for the "timers basic" command, the page
states th
If you only have hosts connected to the switch (not L2 devices),
enable port-fast on the host ports. This eliminates the
spanning tree states on the port and thus the port begins
forwarding packets with a few seconds of the link coming online.
This might be the problem if static IPs are assigne
NRF makes a very good point below about OSS systems. Pulling this
off from the original thread to take the discussion in a differnent
direction.
As we probably all would agree, the largest cost in running a
network is not the engineering cost or the capital costs, but
rather the cost of operatin
Been reading Doyvle V1 IS-IS chapter. Also been reading the
PDF on cisco's web site regarding IS-IS.
Some questions based on this reading.
1) Why is it that the IS-IS model of having the router be in
only a single area, as opposed to where an OSPF router can be in
multiple areas results in signi
and more of the opertional support work will be done up
front as
part of the design engineering and this will include the OIDs and
thresholds
the NM folks and tools should be monitoring.
"Howard C. Berkowitz" wrote:
>
> At 4:31 PM ?? 1/3/03, bergenpeak wrote:
> >
WHen the DHCP packet is forwarded, the DHCP relay agent will insert the
primary IP address of the interface the packet was received on into the
DHCP packet's giaddr field.
When adding secondaries to an interface where you're doing DHCP, make
sure:
- routing to the primaries and secondaries is in
In the docs I've read (and I think this was posted on this list as
well), one might use E2s when you've got one exit point that is always
prefered over the other(s). This might happen if you've got 2 ISPs
and one configured as a backup only. The primary exit point is always
prefered, regardless
I might be misunderstanding the question, but it's pretty common
for an OSPF router in area 0 to originate a default. If you have
a stub area defined, you could configure the ABR with
"default-information
originate" and it will gen the type 3 LSA into the stub only if it sees
a
default. Testing c
Question about route reflector operation.
It appears that a RR, when provided with multiple routes to the
same destination, will pick the best path and then reflect this
best path to the appropriate set of clients and non-clients.
I had expected that the RR would simply just reflect routes and
I think the general ideas are as follows:
- OSPF provides a mechanism to filter LSA (routing information). This
is done within the OSPF spec via area boundaries (ABRs and ASBRs).
- the OSPF area construct works best when all devices in the area
have the same view of toplogy and cost within the a
two paths as to which is closest.
bergenpeak wrote:
>
> Question about route reflector operation.
>
> It appears that a RR, when provided with multiple routes to the
> same destination, will pick the best path and then reflect this
> best path to the appropriate set of clients and
For the folks who have tis up and running-- what tools, if any,
are being used to make sure the VOIP service is operating at
the desired level (delay and jitter bounds within spec, call cut-offs
within spec, etc.)
Thanks
Brad Ellis wrote:
>
> I setup call mangler for us to replace our anal
In the config provided the interface subnets were configured into OSPF
via the
redist as well as via the network command-- which would have
precendence--
redist or network?
Thanks
Peter van Oene wrote:
>
> Hi John,
>
> Although what you have works, I have one suggestion. Redistributing rout
Suppose you have a network with a mix of FE, GE, OC-3/12/48 POS
links.
With the standard OSPF link costing mechanism, all of these links
turn out to have a link cost of 1.
Are there reasons to not go ahead and change the link cost calculation
via the auto-cost reference-bandwidth command to
What are the different ways one might be able to inject bogus routing
announcements into a network running OSPF? I'm trying to determine if
there really is a need for enabling authentication on OSPF or if this is
really not needed.
Suppose OSPF is running throughout a network but that all interf
I've been monitoring the SPF counters on some routers in the network
and wanted to understand if the router performs different parts of the
SPF algorithm depending on what information is currently in the database
and what new information is received via some LSA.
Consider the following two differ
When one does a "show process cpu", one is shown the overall information
and then the breakdown per process.
It's my understanding that the information shown on the summary line,
specifically for the 5 sec information ("30%/24%"), shows the total
CPU utilization and that which has been consumed h
I'd like to setup a group of routers to be in an OSPF sub-area.
The sub-area will connect to the backbone via one or two
ABRs. All other routers in the sub-area will be ASBRs.
The ABRs will not be ASBRs.
>From a design perspective, I want to put these routers into
a sub-area so that I can limit
Suppose I have two ABRs that are supporting the same sub-area.
The ABRs are not directly connected, but can reach each other
through links inside the sub-area.
Suppose a link fails causing the two ABRs to not have connectivity
through the sub-area. The sub-area is therefore partitioned.
Suppose
In a network where FE/GE are used as direct connects between routers
(with a /30 mask), is there any issue from a network or OSPF perspective
if
- one numbers these links with a /31 network in order to save two IPs
per link.
- one uses the ip ospf network point-to-point command remove the need
the configs on the ABR and sub-area routers), using the same area number
will simplify the configs and tool logic.
So, is there some benefit to actually use different sub-area IDs?
Thanks
> bergenpeak wrote:
> >
> > Suppose I have two ABRs that are supporting the same s
t; separate areas to the ABR, you would end up with one area thereby defeating
> your original goal. This is about the only key limitation I can think of
> off hand, but is highly restrictive and certainly overcomes any desire to
> optimize config script tools.
>
> pete
>
&g
When RED is running on an interface, do packets get dropped
before being put into the queue (at the tail, based on ave
queue size, etc) or do they get dropped when they reach the
head of the queue?
Is there any difference in when packets are dropped when WRED
is being used (instead of RED)?
Than
Hi Priscilla,
Thanks much for the response and the RFC reference. Would one still
consider a vendor's implementation to be "RED" (compliant with RFC 2309)
if packets at the head of the queue are dropped instead of at the tail?
Thanks again.
Priscilla Oppenheimer wrote:
>
Your DHCP servers should be looking at the "giaddr" field in the
DHCP packet being relayed by your router. It's this field that
the DHCP server uses to determine which scopes are applicable.
I looked into this before and I believe cisco has changed the default
value it uses for the intserted gia
t as
necessary for the
protocols to work properly.
But trying to unwrap this onion a bit more...
Thanks
Jean-Francois Delrieu wrote:
>
> Bergenpeak,
>
> You should always use default metrics before redistributing or specify a
> metric when reditributing specific routes.
>
/31s are supported on FE and GE link types (as well as POS, etc.)
However,
cisco backed out support in some early versions of the 12.1 code train
(ie
it worked in some versions of 12.0, didn't work in some 12.1, and now
appears
to work again).
RFC 3021 provides details.
bbfaye wrote:
>
> I u
One drawback with 1918 addresses on intermediate physical interfaces is
that
this too makes troubleshooting more difficult. Entities outside of
your domain may troublsehoot problems in or through your network using
traceroute. Traceroute timeouts will originate from the physical
interface
the T
Lets make this discussion real. What major ISPs actually use 1918
addresses
on their physical interfaces?
I know ATT (7018) does not.
nrf wrote:
>
> ""Symon Thurlow"" wrote in message
> [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > Well, I would view an ISP who uses 1918 addresses in the
RFC2328 defines this router to be an ABR. However, there are some
issues with this approach. RFC 3509 defines an alternative behavior
for ABRs. In summary, when the router connects to multiple areas
but not to area 0, the router should not operate as an ABR but
instead should operate as if it w
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