T1 Link
Pardon my ignorance here Is there such a thing as just a "T1 Link"... of what I understand T1 / Frac T1 resides in the physical layer Dont u need something at the Data Link Layer (such as Frame Relay) before you can enable IP or IPX at layer 3 _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
Hi, My limited understanding of the technology tells me that we have something like a telnet session in IP. The telnet application is associated with a socket (port) 23 this goes down the protocol stack and attaches and IP address. Assuming ethernet the packet as it is now goes on down the stack and picks up a MAC address and a framing type. This heads on down to the interface where the electical stuff happens. Once on the wire the electrcal pulses are picked up by the relevant device. When leaving the ethernet one might use a router. This picks up the pulses and basically does the reverse of the above. Identifies the address (IP address) finds the appropriate port as assigns the new framing type and address for the next point. Back down the stack to the interface where the appropriate electrical stuff happens. Along to the remote end and the reverse occurs. This going up and down the appropriate protocol stack happens at each point along the way. In otherwords T1, Frame Relay, ISDN, Serial Asynch modems whatever do not really know nor do they care about the IP layer 3 stuff. In routed type protocols they only care about there own layer 3 and can only understand their own layer 3. Therefore IPX cannot directly talk to IP at the network level. At the layer 2 who cares the data will pass through as long as it has the appropriate frame types. IPX and IP can live happily afterall the layer 3 and above is wrapped up in the appropriate frame. At layer 1 if the elctrical suff all agrees we can send the different frame types afterall it is only electrical pulses but the two ends must agree electrically including timers etc. Long winded but to me it is a simple shuffle of stuff down a protocol stack to the wire -> next device up the stack and so on. Teunis, Hobart Tasmania Australia On Wednesday, February 07, 2001 at 06:36:34 PM, Santosh Koshy wrote: > Pardon my ignorance here > Is there such a thing as just a "T1 Link"... > > of what I understand T1 / Frac T1 resides in the physical layer Dont u > need something at the Data Link Layer (such as Frame Relay) before you can > enable IP or IPX at layer 3 > > > _ > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > -- www.tasmail.com _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
Seeing that nobody had really addressed your question yet, I decided to take a stab at it. T1 is a high-speed digital carrier facility developed by AT&T in the 1950s to support long-haul pulse-code modulation (PCM) voice transmission. T1 provides digital voice circuits or "channels." There are 24 channels per each T1 line or "trunk." AT&T describes their Digital Carrier System as a "two-point, dedicated, high capacity, digital service provided on terrestrial digital facilities capable of transmitting 1.544 Mbps. The interface to the customer can be either a T1 carrier or a higher order multiplexed facility." So, what do you think? To send data on this do we need to encapsulate it? You betcha, as Leo on TechTalk would say. That's why we have "encapsulation frame-relay" and "encapsulation ppp," among others. Hope that helps a bit. Priscilla >On Wednesday, February 07, 2001 at 06:36:34 PM, Santosh Koshy wrote: > > > Pardon my ignorance here > > Is there such a thing as just a "T1 Link"... > > > > of what I understand T1 / Frac T1 resides in the physical layer Dont u > > need something at the Data Link Layer (such as Frame Relay) before you can > > enable IP or IPX at layer 3 > > > > > > _ > > FAQ, list archives, and subscription info: > http://www.groupstudy.com/list/cisco.html > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > > > Priscilla Oppenheimer http://www.priscilla.com _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
Thanks priscilla, that helped tremendously... If that is the case... then what is the most common L2 Encapsulation used when usually setting up a T1 link...(point to point) Is it safe to assume HDLC as that is the default encap on the cisco routers "Priscilla Oppenheimer" <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Seeing that nobody had really addressed your question yet, I decided to > take a stab at it. > > T1 is a high-speed digital carrier facility developed by AT&T in the 1950s > to support long-haul pulse-code modulation (PCM) voice transmission. T1 > provides digital voice circuits or "channels." There are 24 channels per > each T1 line or "trunk." > > AT&T describes their Digital Carrier System as a "two-point, dedicated, > high capacity, digital service provided on terrestrial digital facilities > capable of transmitting 1.544 Mbps. The interface to the customer can be > either a T1 carrier or a higher order multiplexed facility." > > So, what do you think? To send data on this do we need to encapsulate it? > You betcha, as Leo on TechTalk would say. That's why we have "encapsulation > frame-relay" and "encapsulation ppp," among others. > > Hope that helps a bit. > > Priscilla > > > > >On Wednesday, February 07, 2001 at 06:36:34 PM, Santosh Koshy wrote: > > > > > Pardon my ignorance here > > > Is there such a thing as just a "T1 Link"... > > > > > > of what I understand T1 / Frac T1 resides in the physical layer Dont u > > > need something at the Data Link Layer (such as Frame Relay) before you can > > > enable IP or IPX at layer 3 > > > > > > > > > _ > > > FAQ, list archives, and subscription info: > > http://www.groupstudy.com/list/cisco.html > > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > > > > > > > > > > Priscilla Oppenheimer > http://www.priscilla.com > > _ > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
>Seeing that nobody had really addressed your question yet, I decided to >take a stab at it. > >T1 is a high-speed digital carrier facility developed by AT&T in the 1950s >to support long-haul pulse-code modulation (PCM) voice transmission. T1 >provides digital voice circuits or "channels." There are 24 channels per >each T1 line or "trunk." > >AT&T describes their Digital Carrier System as a "two-point, dedicated, >high capacity, digital service provided on terrestrial digital facilities >capable of transmitting 1.544 Mbps. The interface to the customer can be >either a T1 carrier or a higher order multiplexed facility." > >So, what do you think? To send data on this do we need to encapsulate it? >You betcha, as Leo on TechTalk would say. That's why we have "encapsulation >frame-relay" and "encapsulation ppp," among others. > >Hope that helps a bit. > >Priscilla Let me come at this a little differently, and get one of my opportunities to say something is layered -- just not exactly corresponding to the Seven Deadly Layers. At the lowest level are the signal (i.e., electrical or optical) standards that define single bits. These may be associated with a particular connector, but they also have particular timing characteristics. DS1 and E1 describe bit streams that run at certain data rates: 1.544 MBps for DS1 2.032 Mbps for E1. I distinguish between the DS1 and T1 signals. T1 is a DS1 signal specifically running over copper pairs. You can have radio or optical DS1 that is not on wire. DS-x also is a level in a digital multiplexing hierarchy. DS-x or E-x streams are isochronous: bits have to fall into time slots in the stream, but there are no in-stream timing bits (as with asynchronous signals) or external timing (as with synchronous signals). For the next layer up, there are constraints on the bit stream. These constraints are used to maintain signal quality, for limited control (e.g., triggering loopbacks), etc. Bit level framing includes algorithms such as AMI and B8ZS. The next level up synchronizes multiple stream into frames, so the frames can be associated with multiplexed subchannels. SF and ESF are common methods, along with CAS and CCS as means of sending control information. On top of the subchannels go the basic data link framing from protocols such as frame or ATM with AAL. Both of these families go up yet another layer, with a protocol type field starting the data field, a field based on 802.2. It's late. I hope I'm not rambling too much. > > > >>On Wednesday, February 07, 2001 at 06:36:34 PM, Santosh Koshy wrote: >> >> > Pardon my ignorance here >> > Is there such a thing as just a "T1 Link"... >> > >> > of what I understand T1 / Frac T1 resides in the physical layer Dont u >> > need something at the Data Link Layer (such as Frame Relay) before you can >> > enable IP or IPX at layer 3 >> > >> > >> > _ >> > FAQ, list archives, and subscription info: >> http://www.groupstudy.com/list/cisco.html >> > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] >> > >> > > > > > >Priscilla Oppenheimer >http://www.priscilla.com > >_ >FAQ, list archives, and subscription info: >http://www.groupstudy.com/list/cisco.html >Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] -- "What Problem are you trying to solve?" ***send Cisco questions to the list, so all can benefit -- not directly to me*** Howard C. Berkowitz [EMAIL PROTECTED] Technical Director, CertificationZone.com Senior Mgr. IP Protocols & Algorithms, Core Networks Advanced Technology, NortelNetworks (for ID only) but Cisco stockholder! "retired" Certified Cisco Systems Instructor (CID) #93005 _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
At 11:58 PM 2/7/01, Santosh Koshy wrote: >Thanks priscilla, that helped tremendously... >If that is the case... then what is the most common L2 Encapsulation used >when usually setting up a T1 link...(point to point) >Is it safe to assume HDLC as that is the default encap on the cisco routers HDLC is common for point-to-point links, but Cisco's HDLC is non-standard, so if you were connecting to a non-Cisco router you would probably use PPP. In many parts of the world, Frame Relay is the most common WAN encapsulation, but it sounded like you were asking about point-to-poin circuits, so that might not be relevant. Priscilla >- Original Message - >From: "Priscilla Oppenheimer" <[EMAIL PROTECTED]> >Newsgroups: groupstudy.cisco >Sent: Wednesday, February 07, 2001 11:50 PM >Subject: Re: T1 Link > > > > Seeing that nobody had really addressed your question yet, I decided to > > take a stab at it. > > > > T1 is a high-speed digital carrier facility developed by AT&T in the 1950s > > to support long-haul pulse-code modulation (PCM) voice transmission. T1 > > provides digital voice circuits or "channels." There are 24 channels per > > each T1 line or "trunk." > > > > AT&T describes their Digital Carrier System as a "two-point, dedicated, > > high capacity, digital service provided on terrestrial digital facilities > > capable of transmitting 1.544 Mbps. The interface to the customer can be > > either a T1 carrier or a higher order multiplexed facility." > > > > So, what do you think? To send data on this do we need to encapsulate it? > > You betcha, as Leo on TechTalk would say. That's why we have >"encapsulation > > frame-relay" and "encapsulation ppp," among others. > > > > Hope that helps a bit. > > > > Priscilla > > > > > > > > >On Wednesday, February 07, 2001 at 06:36:34 PM, Santosh Koshy wrote: > > > > > > > Pardon my ignorance here > > > > Is there such a thing as just a "T1 Link"... > > > > > > > > of what I understand T1 / Frac T1 resides in the physical layer >Dont u > > > > need something at the Data Link Layer (such as Frame Relay) before you >can > > > > enable IP or IPX at layer 3 > > > > > > > > > > > > _ > > > > FAQ, list archives, and subscription info: > > > http://www.groupstudy.com/list/cisco.html > > > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > > > > > > > > > > > > > > > > > Priscilla Oppenheimer > > http://www.priscilla.com > > > > _ > > FAQ, list archives, and subscription info: >http://www.groupstudy.com/list/cisco.html > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > Priscilla Oppenheimer http://www.priscilla.com _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
Priscilla, In the Cisco Networking Academy (Sem4) curriculum, significantly more time is spent on PPP operation & configuration than Cisco's HDLC. One might get the impression from this that Cisco is pushing the use of PPP (with its better security features) over its own HDLC even in an all Cisco environment. Tom Lisa, Instructor, CCNA, CCAI Community College of Southern Nevada Cisco Regional Networking Academy Priscilla Oppenheimer wrote: > At 11:58 PM 2/7/01, Santosh Koshy wrote: > >Thanks priscilla, that helped tremendously... > >If that is the case... then what is the most common L2 Encapsulation used > >when usually setting up a T1 link...(point to point) > >Is it safe to assume HDLC as that is the default encap on the cisco routers > > HDLC is common for point-to-point links, but Cisco's HDLC is non-standard, > so if you were connecting to a non-Cisco router you would probably use PPP. > > In many parts of the world, Frame Relay is the most common WAN > encapsulation, but it sounded like you were asking about point-to-poin > circuits, so that might not be relevant. > > Priscilla > > >- Original Message - > >From: "Priscilla Oppenheimer" <[EMAIL PROTECTED]> > >Newsgroups: groupstudy.cisco > >Sent: Wednesday, February 07, 2001 11:50 PM > >Subject: Re: T1 Link > > > > > > > Seeing that nobody had really addressed your question yet, I decided to > > > take a stab at it. > > > > > > T1 is a high-speed digital carrier facility developed by AT&T in the 1950s > > > to support long-haul pulse-code modulation (PCM) voice transmission. T1 > > > provides digital voice circuits or "channels." There are 24 channels per > > > each T1 line or "trunk." > > > > > > AT&T describes their Digital Carrier System as a "two-point, dedicated, > > > high capacity, digital service provided on terrestrial digital facilities > > > capable of transmitting 1.544 Mbps. The interface to the customer can be > > > either a T1 carrier or a higher order multiplexed facility." > > > > > > So, what do you think? To send data on this do we need to encapsulate it? > > > You betcha, as Leo on TechTalk would say. That's why we have > >"encapsulation > > > frame-relay" and "encapsulation ppp," among others. > > > > > > Hope that helps a bit. > > > > > > Priscilla > > > > > > > > > > > > >On Wednesday, February 07, 2001 at 06:36:34 PM, Santosh Koshy wrote: > > > > > > > > > Pardon my ignorance here > > > > > Is there such a thing as just a "T1 Link"... > > > > > > > > > > of what I understand T1 / Frac T1 resides in the physical layer > >Dont u > > > > > need something at the Data Link Layer (such as Frame Relay) before you > >can > > > > > enable IP or IPX at layer 3 > > > > > > > > > > > > > > > _ > > > > > FAQ, list archives, and subscription info: > > > > http://www.groupstudy.com/list/cisco.html > > > > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > > > > > > > > > > > > > > > > > > > > > > > > Priscilla Oppenheimer > > > http://www.priscilla.com _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
At 03:09 PM 2/8/01, Tom Lisa wrote:
>Priscilla,
>
>In the Cisco Networking Academy (Sem4) curriculum, significantly more time
>is spent on
>PPP operation & configuration than Cisco's HDLC.
That's just because you can say something useful about PPP. It's great for
instructors. They can show off how much they have learned about PAP and
CHAP. &;-)
What can you say about Cisco HDLC? Not much, though here are some comments
on Cisco HDLC, since it is being talked about so much today:
cisco's default encapsulation on synchronous serial lines uses HDLC framing,
with packet contents defined as follows:
The first ("address") octet is set to 0x0F for unicast packets and 0x8F
for broadcast packets. Broadcast just means that the higher-level protocol
thought this was a broadcast packet; cisco doesn't support multidrop
HDLC at this time.
The second ("control") octet is always 0.
The next two octets are a 16-bit protocol code, sent most-significant-first.
These codes are usually Ethernet type codes. cisco has added some codes to
support packet types that don't appear on Ethernets. The current list of codes
is as follows:
TYPE_PUP0x0200 PUP
TYPE_XNS0x0600 XNS
TYPE_IP10MB 0x0800 IP
TYPE_CHAOS 0x0804 Chaos
TYPE_IEEE_SPANNING 0x4242 DSAP/SSAP for IEEE bridge spanning
prot.
TYPE_DECNET 0x6003 DECnet phase IV
TYPE_BRIDGE 0x6558 Bridged Ethernet/802.3 packet
TYPE_APOLLO 0x8019 Apollo domain
TYPE_REVERSE_ARP0x8035 cisco SLARP (not real reverse ARP!)
TYPE_DEC_SPANNING 0x8038 DEC bridge spanning tree protocol
TYPE_ETHERTALK 0x809b Apple EtherTalk
TYPE_AARP 0x80f3 Appletalk ARP
TYPE_NOVELL10x8137 Novell IPX
TYPE_CLNS 0xFEFE ISO CLNP/ISO ES-IS DSAP/SSAP
This list is shared between serial and Ethernet encapsulations. Not all
these codes will necessarily appear on serial lines. This list will probably
be extended as cisco adds support for more protocols.
Bytes after this are higher-level protocol data. These normally look the
same as they'd look on Ethernet. Bridging packets include Ethernet/802.3
MAC headers; no other packets do.
Packets with type 8035 (reverse ARP) don't contain reverse ARP data as
they would on an Ethernet. Instead, they carry a protocol cisco refers to
as SLARP. SLARP has two functions: dynamic IP address determination and
serial line keepalive.
The serial line model supported by SLARP assumes that each serial line is
a separate IP subnet, and that one end of the line is host number 1, while
the other end is host number 2. The SLARP address resolution protocol allows
system A to request that system B tell system A system B's IP address,
along with the IP netmask to be used on the network. It does this by sending
a SLARP address resolution request packet, to which system B responds with a
SLARP address resolution reply packet. System A then attempts to determine its
own IP address based on the address of system B. If the host portion of system
B's address is 1, system A will use 2 for the host portion of its own IP
address. Conversely, if system B's IP host number is 2, system A will use IP
host number 1. If system B replies with any IP host number other than 1 or 2,
system A assumes that system B is unable to provide it with an address via
SLARP.
For the SLARP keepalive protocol, each system sends the other a keepalive
packet at a user-configurable interval. The default interval is 10 seconds.
Both systems must use the same interval to ensure reliable operation.
Each system assigns sequence numbers to the keepalive packets it sends,
starting with zero, independent of the other system. These sequence numbers
are included in the keepalive packets sent to the other system. Also included
in each keepalive packet is the sequence number of the last keepalive packet
_received_ from the other system, as assigned by the other system. This number
is called the returned sequence number. Each system keeps track of the last
returned sequence number it has received. Immediately before sending a
keepalive
packet, it compares the sequence number of the packet it is about to send with
the returned sequence number in the last keepalive packet it has received.
If the two differ by 3 or more, it considers the line to have failed, and
will route no further higher-level data across it until an acceptable keepalive
response is received.
There is interaction between the SLARP address resolution protocol and the
SLARP keepalive protocol. When one end of a serial line receives a SLARP
address resolution request packet, it assumes that the other end has restarted
its serial interface and reset its keepalive sequence numbers. In addition
to responding to the address resolution request, it will act as if the
other end had sent
Re: T1 Link
WOW!! Great stuff, especially the SLARP info! I think I'll save this for when we
start teaching CCNP level courses. It would frighten my CCNA students.
BTW, for all Las Vegas area members, the Community College will be offering the
BSCN course in the Fall Semester. It will be offered at both the Cheyenne and
Henderson campuses. Email me directly if you would like more info.
Tom Lisa, Instructor, CCNA, CCAI
Community College of Southern Nevada
Cisco Regional Networking Academy
Priscilla Oppenheimer wrote:
> At 03:09 PM 2/8/01, Tom Lisa wrote:
> >Priscilla,
> >
> >In the Cisco Networking Academy (Sem4) curriculum, significantly more time
> >is spent on
> >PPP operation & configuration than Cisco's HDLC.
>
> That's just because you can say something useful about PPP. It's great for
> instructors. They can show off how much they have learned about PAP and
> CHAP. &;-)
>
> What can you say about Cisco HDLC? Not much, though here are some comments
> on Cisco HDLC, since it is being talked about so much today:
>
> cisco's default encapsulation on synchronous serial lines uses HDLC framing,
> with packet contents defined as follows:
>
> The first ("address") octet is set to 0x0F for unicast packets and 0x8F
> for broadcast packets. Broadcast just means that the higher-level protocol
> thought this was a broadcast packet; cisco doesn't support multidrop
> HDLC at this time.
>
> The second ("control") octet is always 0.
>
> The next two octets are a 16-bit protocol code, sent most-significant-first.
> These codes are usually Ethernet type codes. cisco has added some codes to
> support packet types that don't appear on Ethernets. The current list of codes
> is as follows:
>
> TYPE_PUP0x0200 PUP
> TYPE_XNS0x0600 XNS
> TYPE_IP10MB 0x0800 IP
> TYPE_CHAOS 0x0804 Chaos
> TYPE_IEEE_SPANNING 0x4242 DSAP/SSAP for IEEE bridge spanning
> prot.
> TYPE_DECNET 0x6003 DECnet phase IV
> TYPE_BRIDGE 0x6558 Bridged Ethernet/802.3 packet
> TYPE_APOLLO 0x8019 Apollo domain
> TYPE_REVERSE_ARP0x8035 cisco SLARP (not real reverse ARP!)
> TYPE_DEC_SPANNING 0x8038 DEC bridge spanning tree protocol
> TYPE_ETHERTALK 0x809b Apple EtherTalk
> TYPE_AARP 0x80f3 Appletalk ARP
> TYPE_NOVELL10x8137 Novell IPX
> TYPE_CLNS 0xFEFE ISO CLNP/ISO ES-IS DSAP/SSAP
>
> This list is shared between serial and Ethernet encapsulations. Not all
> these codes will necessarily appear on serial lines. This list will probably
> be extended as cisco adds support for more protocols.
>
> Bytes after this are higher-level protocol data. These normally look the
> same as they'd look on Ethernet. Bridging packets include Ethernet/802.3
> MAC headers; no other packets do.
>
> Packets with type 8035 (reverse ARP) don't contain reverse ARP data as
> they would on an Ethernet. Instead, they carry a protocol cisco refers to
> as SLARP. SLARP has two functions: dynamic IP address determination and
> serial line keepalive.
>
> The serial line model supported by SLARP assumes that each serial line is
> a separate IP subnet, and that one end of the line is host number 1, while
> the other end is host number 2. The SLARP address resolution protocol allows
> system A to request that system B tell system A system B's IP address,
> along with the IP netmask to be used on the network. It does this by sending
> a SLARP address resolution request packet, to which system B responds with a
> SLARP address resolution reply packet. System A then attempts to determine its
> own IP address based on the address of system B. If the host portion of system
> B's address is 1, system A will use 2 for the host portion of its own IP
> address. Conversely, if system B's IP host number is 2, system A will use IP
> host number 1. If system B replies with any IP host number other than 1 or 2,
> system A assumes that system B is unable to provide it with an address via
> SLARP.
>
> For the SLARP keepalive protocol, each system sends the other a keepalive
> packet at a user-configurable interval. The default interval is 10 seconds.
> Both systems must use the same interval to ensure reliable operation.
> Each system assigns sequence numbers to the keepalive packets it sends,
> starting with zero, independent of the other system. These sequence numbers
> are included in the keepalive packets sent to the other system. Also included
> in each keepalive packet is the sequence number of the last keepalive packet
> _received_ from the other system, as assigned by the other system. This number
> is called the returned sequence number. Each system keeps track of the last
> returned sequence number it has received. Immediately before sending a
> keepalive
> packet, it compares the sequence number of the packet
Re: T1 Link
>WOW!! Great stuff, especially the SLARP info! I think I'll save >this for when we >start teaching CCNP level courses. It would frighten my CCNA students. SLARP, I believe, only can be properly understood with a thorough grounding in Monty Python. It rolls over the tongue so sensuously, so langurously...wink wink nudge nudge, know what I mean? It puzzles me that a country that produced Monty Python is not more dominant in networking. But, I am also of the opinion that Australia should dominate multivendor networking, since any country that produced the platypus should be culturally inclined to making ill-matched components work together. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
Pricilla, please tell me that you pasted that from a file you had. I'd hate to think you spent 3 hours typing that out. Wow, that's actually the longest post I've seen in the year I've been on. =o) Mark Z. In a message dated 2/8/01 8:46:12 PM Eastern Standard Time, [EMAIL PROTECTED] writes: > That's just because you can say something useful about PPP. It's great for > instructors. They can show off how much they have learned about PAP and > CHAP. &;-) > > What can you say about Cisco HDLC? Not much, though here are some comments > on Cisco HDLC, since it is being talked about so much today: > > :::SNIP:: _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
Yup, SLARP is pretty cool. It's one good reason to use HDLC. It makes
configuration so easy. Also, the students will love saying SLARP. I'm
helping out with the academy at our local high school, as I've mentioned
before. Those students will love saying SLARP, over and over and over again.
Lately, they have taken to giving me a hard time about "Sniffer." They
snicker every time I say it. It's kind of embarrassing, to be honest. I
want them to take it seriously. It's all boys, so I'm worried that Sniffer
means something dirty. Sigh.
I'm having a hard time, in general, teaching networking to kids who don't
really love it and don't have to know it for their jobs. I got spoiled,
teaching classes to people who had paid money to be there and needed the
info to survive on the job. I'm sure it's quite different at a community
college, but you probably get some young people too. Any advice?? Thanks!
Talk to you later!
Priscilla
At 06:38 PM 2/8/01, Tom Lisa wrote:
>WOW!! Great stuff, especially the SLARP info! I think I'll save this for
>when we
>start teaching CCNP level courses. It would frighten my CCNA students.
>
>BTW, for all Las Vegas area members, the Community College will be
>offering the
>BSCN course in the Fall Semester. It will be offered at both the Cheyenne and
>Henderson campuses. Email me directly if you would like more info.
>
>Tom Lisa, Instructor, CCNA, CCAI
>Community College of Southern Nevada
>Cisco Regional Networking Academy
>
>Priscilla Oppenheimer wrote:
>
> > At 03:09 PM 2/8/01, Tom Lisa wrote:
> > >Priscilla,
> > >
> > >In the Cisco Networking Academy (Sem4) curriculum, significantly more time
> > >is spent on
> > >PPP operation & configuration than Cisco's HDLC.
> >
> > That's just because you can say something useful about PPP. It's great for
> > instructors. They can show off how much they have learned about PAP and
> > CHAP. &;-)
> >
> > What can you say about Cisco HDLC? Not much, though here are some comments
> > on Cisco HDLC, since it is being talked about so much today:
> >
> > cisco's default encapsulation on synchronous serial lines uses HDLC
> framing,
> > with packet contents defined as follows:
> >
> > The first ("address") octet is set to 0x0F for unicast packets and 0x8F
> > for broadcast packets. Broadcast just means that the higher-level protocol
> > thought this was a broadcast packet; cisco doesn't support multidrop
> > HDLC at this time.
> >
> > The second ("control") octet is always 0.
> >
> > The next two octets are a 16-bit protocol code, sent
> most-significant-first.
> > These codes are usually Ethernet type codes. cisco has added some codes to
> > support packet types that don't appear on Ethernets. The current list
> of codes
> > is as follows:
> >
> > TYPE_PUP0x0200 PUP
> > TYPE_XNS0x0600 XNS
> > TYPE_IP10MB 0x0800 IP
> > TYPE_CHAOS 0x0804 Chaos
> > TYPE_IEEE_SPANNING 0x4242 DSAP/SSAP for IEEE bridge spanning
> > prot.
> > TYPE_DECNET 0x6003 DECnet phase IV
> > TYPE_BRIDGE 0x6558 Bridged Ethernet/802.3 packet
> > TYPE_APOLLO 0x8019 Apollo domain
> > TYPE_REVERSE_ARP0x8035 cisco SLARP (not real reverse
> ARP!)
> > TYPE_DEC_SPANNING 0x8038 DEC bridge spanning tree protocol
> > TYPE_ETHERTALK 0x809b Apple EtherTalk
> > TYPE_AARP 0x80f3 Appletalk ARP
> > TYPE_NOVELL10x8137 Novell IPX
> > TYPE_CLNS 0xFEFE ISO CLNP/ISO ES-IS DSAP/SSAP
> >
> > This list is shared between serial and Ethernet encapsulations. Not all
> > these codes will necessarily appear on serial lines. This list will
> probably
> > be extended as cisco adds support for more protocols.
> >
> > Bytes after this are higher-level protocol data. These normally look the
> > same as they'd look on Ethernet. Bridging packets include Ethernet/802.3
> > MAC headers; no other packets do.
> >
> > Packets with type 8035 (reverse ARP) don't contain reverse ARP data as
> > they would on an Ethernet. Instead, they carry a protocol cisco refers to
> > as SLARP. SLARP has two functions: dynamic IP address determination and
> > serial line keepalive.
> >
> > The serial line model supported by SLARP assumes that each serial line is
> > a separate IP subnet, and that one end of the line is host number 1, while
> > the other end is host number 2. The SLARP address resolution protocol
> allows
> > system A to request that system B tell system A system B's IP address,
> > along with the IP netmask to be used on the network. It does this by
> sending
> > a SLARP address resolution request packet, to which system B responds
> with a
> > SLARP address resolution reply packet. System A then attempts to
> determine its
> > own IP address based on the address of system B. If the host portion of
> syst
Re: T1 Link
Sorry, I should have given credit for the info about HDLC. I got it from somewhere on Cisco's site, but I can't find it again. I've had it for a while. It's been posted to this list a few times before by Howard and others. Maybe I got it from Howard. You'll note that is uses "cisco" instead of "Cisco." That shows how old it is. Cisco used to go by "cisco." Too bad, I can't claim to have written it all myself! &;-) Priscilla At 11:18 PM 2/8/01, [EMAIL PROTECTED] wrote: >Pricilla, please tell me that you pasted that from a file you had. I'd hate >to think you spent 3 hours typing that out. Wow, that's actually the longest >post I've seen in the year I've been on. =o) > >Mark Z. > >In a message dated 2/8/01 8:46:12 PM Eastern Standard Time, >[EMAIL PROTECTED] writes: > > >>That's just because you can say something useful about PPP. It's great for >>instructors. They can show off how much they have learned about PAP and >>CHAP. &;-) >> >>What can you say about Cisco HDLC? Not much, though here are some comments >>on Cisco HDLC, since it is being talked about so much today: >:::SNIP:: Priscilla Oppenheimer http://www.priscilla.com _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
>Sorry, I should have given credit for the info about HDLC. I got it from >somewhere on Cisco's site, but I can't find it again. I've had it for a while. It's been posted to this list a > few times before by Howard and >others. Maybe I got it from Howard. I've posted it, but I think it's originally written by Chops Westerfield, who I think was something like Cisco employee #4 and was top-level support for many years. > >You'll note that is uses "cisco" instead of "Cisco." That shows how old it >is. Cisco used to go by "cisco." > >Too bad, I can't claim to have written it all myself! &;-) > >Priscilla > _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
Priscilla Oppenheimer wrote: > > Yup, SLARP is pretty cool. It's one good reason to use HDLC. It makes > configuration so easy. Also, the students will love saying SLARP. I'm > helping out with the academy at our local high school, as I've mentioned > before. Those students will love saying SLARP, over and over and over again. > Unless autoinstall has changed in the last year or so, it used to first try HCLC, then PPP, then Frame Relay, and I think there was a forth one. Yes, SLARP is very cool... when you want it. When you don't, it sure adds a bunch of time -- if the SLARP succeeds, then IOS gets very patient broadcasting rDNS, TFTP, etc. etc. > I'm having a hard time, in general, teaching networking to kids who don't > really love it and don't have to know it for their jobs. I got spoiled, > teaching classes to people who had paid money to be there and needed the > info to survive on the job. I'm sure it's quite different at a community > college, but you probably get some young people too. Any advice?? Thanks! > Hmmm, tell them you're going to teach them TCP/IP operation so they can learn how to tweak their TCP stack and soup up those Napster downloads! :-) :-) - Marty _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
Yes, it's definitely worth mentioning that SLARP can be a pain, especially in a lab environment or training classroom. You connect two routers together over a serial back-to-back cable. Turn on one router and configure the IP address and subnet mask. Turn on the other router, and if you're not quick, the darn thing will SLARP. Then it sits there forever (seems like forever at least), doing reverse DNS to find its name, and trying to find a TFTP server to download the rest of its config. To make matters worse it puts the "service config" command in the config file, which causes it to look for a server every time you reboot (if you save the config). A few times a month we get the question about the router looking for its config from a server. The answers always say to add "no service config" to your config, but the answers don't explain how the annoying "service config" line got in your config to start with. It's probably that slippery SLARP. To be totally accurate, it's AutoInstall that does this, but that's not s fun to say. &;-) SLARP is one component of AutoInstall in an HDLC environment. AutoInstall can also work with Frame Relay, Ethernet, Token Ring, and FDDI, according to the doc here: http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/fun_c/fcprt1/fccfgtoo.htm Thanks for the great ideas on making TCP more relevant to my students, Marty. Offline, if you get a chance, could you tell me more about tweaking your TCP stack on Windows? Thanks. Priscilla At 12:37 PM 2/10/01, Marty Adkins wrote: >Priscilla Oppenheimer wrote: > > > > Yup, SLARP is pretty cool. It's one good reason to use HDLC. It makes > > configuration so easy. Also, the students will love saying SLARP. I'm > > helping out with the academy at our local high school, as I've mentioned > > before. Those students will love saying SLARP, over and over and over > again. > > >Unless autoinstall has changed in the last year or so, it used to first >try HCLC, then PPP, then Frame Relay, and I think there was a forth one. >Yes, SLARP is very cool... when you want it. When you don't, it sure >adds a bunch of time -- if the SLARP succeeds, then IOS gets very patient >broadcasting rDNS, TFTP, etc. etc. > > > I'm having a hard time, in general, teaching networking to kids who don't > > really love it and don't have to know it for their jobs. I got spoiled, > > teaching classes to people who had paid money to be there and needed the > > info to survive on the job. I'm sure it's quite different at a community > > college, but you probably get some young people too. Any advice?? Thanks! > > >Hmmm, tell them you're going to teach them TCP/IP operation so they can >learn how to tweak their TCP stack and soup up those Napster downloads! >:-) :-) > >- Marty Priscilla Oppenheimer http://www.priscilla.com _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: T1 Link
Thanks for the additional info Priscilla. I had always thought that the "service config" statement was a default with IOS 11.0 and later. Tom Lisa, Instructor, CCNA, CCAI Community College of Southern Nevada Cisco Regional Networking Academy Priscilla Oppenheimer wrote: > Yes, it's definitely worth mentioning that SLARP can be a pain, especially > in a lab environment or training classroom. You connect two routers > together over a serial back-to-back cable. Turn on one router and configure > the IP address and subnet mask. Turn on the other router, and if you're not > quick, the darn thing will SLARP. Then it sits there forever (seems like > forever at least), doing reverse DNS to find its name, and trying to find a > TFTP server to download the rest of its config. To make matters worse it > puts the "service config" command in the config file, which causes it to > look for a server every time you reboot (if you save the config). > > A few times a month we get the question about the router looking for its > config from a server. The answers always say to add "no service config" to > your config, but the answers don't explain how the annoying "service > config" line got in your config to start with. It's probably that slippery > SLARP. > > To be totally accurate, it's AutoInstall that does this, but that's not s > fun to say. &;-) SLARP is one component of AutoInstall in an HDLC > environment. AutoInstall can also work with Frame Relay, Ethernet, Token > Ring, and FDDI, according to the doc here: > > >http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/fun_c/fcprt1/fccfgtoo.htm > > Thanks for the great ideas on making TCP more relevant to my students, > Marty. Offline, if you get a chance, could you tell me more about tweaking > your TCP stack on Windows? Thanks. > > Priscilla > > At 12:37 PM 2/10/01, Marty Adkins wrote: > >Priscilla Oppenheimer wrote: > > > > > > Yup, SLARP is pretty cool. It's one good reason to use HDLC. It makes > > > configuration so easy. Also, the students will love saying SLARP. I'm > > > helping out with the academy at our local high school, as I've mentioned > > > before. Those students will love saying SLARP, over and over and over > > again. > > > > >Unless autoinstall has changed in the last year or so, it used to first > >try HCLC, then PPP, then Frame Relay, and I think there was a forth one. > >Yes, SLARP is very cool... when you want it. When you don't, it sure > >adds a bunch of time -- if the SLARP succeeds, then IOS gets very patient > >broadcasting rDNS, TFTP, etc. etc. > > > > > I'm having a hard time, in general, teaching networking to kids who don't > > > really love it and don't have to know it for their jobs. I got spoiled, > > > teaching classes to people who had paid money to be there and needed the > > > info to survive on the job. I'm sure it's quite different at a community > > > college, but you probably get some young people too. Any advice?? Thanks! > > > > >Hmmm, tell them you're going to teach them TCP/IP operation so they can > >learn how to tweak their TCP stack and soup up those Napster downloads! > >:-) :-) > > > >- Marty > > > > Priscilla Oppenheimer > http://www.priscilla.com > > _ > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
appropriate new terminology (was Re: T1 Link)
>At 11:58 PM 2/7/01, Santosh Koshy wrote: >>Thanks priscilla, that helped tremendously... >>If that is the case... then what is the most common L2 Encapsulation used >>when usually setting up a T1 link...(point to point) >>Is it safe to assume HDLC as that is the default encap on the cisco routers > >HDLC is common for point-to-point links, but Cisco's HDLC is non-standard, >so if you were connecting to a non-Cisco router you would probably use PPP. > >In many parts of the world, Frame Relay is the most common WAN encapsulation, but it sounded like you were asking about point-to-poin ^ My eyes first interpreted this as a point-to-pain circuit. I then realized I've worked with quite a few of those. >circuits, so that might not be relevant. > >Priscilla > > >- Original Message - _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Motivations and Age (was Re: T1 Link)
>Yup, SLARP is pretty cool. It's one good reason to use HDLC. It makes >configuration so easy. Also, the students will love saying SLARP. I'm >helping out with the academy at our local high school, as I've mentioned >before. Those students will love saying SLARP, over and over and over again. > >Lately, they have taken to giving me a hard time about "Sniffer." They >snicker every time I say it. It's kind of embarrassing, to be honest. I >want them to take it seriously. It's all boys, so I'm worried that Sniffer >means something dirty. Sigh. that context is rather clean, compared to my metaphor for doing a wireless transfer between two Palm Pilots: the yuppie version of dogs sniffing one another. > >I'm having a hard time, in general, teaching networking to kids who don't >really love it and don't have to know it for their jobs. I got spoiled, >teaching classes to people who had paid money to be there and needed the >info to survive on the job. I'm sure it's quite different at a community >college, but you probably get some young people too. Any advice?? Thanks! > >Talk to you later! > >Priscilla > Priscilla, I think you raise some very good points, and this list may actually be a very good place to get insights into it. My teenage motivations were a long time ago in memory. At the time, routers were steam powered...actually, they hadn't been invented yet. My weird nerd interests were much more in microbiology. I'm afraid that I often go into hysterical giggling when people start saying their generation is so cool because they grew up with the technology...well, I can sort of say that too. Sure, I know people that have been doing networking longer than I have...Scott Bradner and Vint Cerf come to mind. So my perspective is going to be different from someone of the same age who is just transitioning into the field. But it's also going to be different from someone in high school or early college. I'd encourage people here that have peers in the situation Priscilla describes -- in networking classes, without much life experience -- help us understand how best to motivate them, how to communicate with them. You've also made the point with respect to the acceptance of software piracy, that perhaps there is a sense of entitlement by people that don't have a personal sense of earning one's living through product development. I'd pose the question to the younger people on the list -- does this fit your experience, or are we completely in left field? _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Wireless for backup T1 link??? [7:3651]
Have anyone experience with Wireless technology for backup link solution? I have 2 cities: NY city and LA connected via T1 point to point and looking for a backup solution that does not cost too much. Is wireless is a good solution for this backup? Thanks! Kim. __ Do You Yahoo!? Yahoo! Auctions - buy the things you want at great prices http://auctions.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=3651&t=3651 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wireless for backup T1 link??? [7:3651]
Thats an awful long distance. Thought about frame relay? Brian "Sonic" Whalen Success = Preparation + Opportunity On Tue, 8 May 2001, Kim Seng wrote: > Have anyone experience with Wireless technology for > backup link solution? I have 2 cities: NY city and LA > connected via T1 point to point and looking for a > backup solution that does not cost too much. Is > wireless is a good solution for this backup? > > Thanks! > > Kim. > > __ > Do You Yahoo!? > Yahoo! Auctions - buy the things you want at great prices > http://auctions.yahoo.com/ > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=3654&t=3651 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wireless for backup T1 link??? [7:3651]
No! Generally speaking, ISDN Backup is the best solution in term of money. ""Kim Seng"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Have anyone experience with Wireless technology for > backup link solution? I have 2 cities: NY city and LA > connected via T1 point to point and looking for a > backup solution that does not cost too much. Is > wireless is a good solution for this backup? > > Thanks! > > Kim. > > __ > Do You Yahoo!? > Yahoo! Auctions - buy the things you want at great prices > http://auctions.yahoo.com/ > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=3658&t=3651 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wireless for backup T1 link??? [7:3651]
Maybe between to buildings, but I would not think between two coastal cities. If I recall, the wireless solution I saw when working with the government cost out around $250,000 per month for 50 Meg link. Apples to oranges I know, but even if it were to cost a 10th or 20th... the sum would be outrageous for T1 or Frame. Phil - Original Message - From: Kim Seng To: Sent: Tuesday, May 08, 2001 2:06 PM Subject: Wireless for backup T1 link??? [7:3651] > Have anyone experience with Wireless technology for > backup link solution? I have 2 cities: NY city and LA > connected via T1 point to point and looking for a > backup solution that does not cost too much. Is > wireless is a good solution for this backup? > > Thanks! > > Kim. > > __ > Do You Yahoo!? > Yahoo! Auctions - buy the things you want at great prices > http://auctions.yahoo.com/ > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=3667&t=3651 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wireless for backup T1 link??? [7:3651]
Thought about buying dsl internet access at each office then building a secure tunnel between the two? Brian "Sonic" Whalen Success = Preparation + Opportunity On Tue, 8 May 2001, Circusnuts wrote: > Maybe between to buildings, but I would not think between two coastal > cities. If I recall, the wireless solution I saw when working with the > government cost out around $250,000 per month for 50 Meg link. Apples to > oranges I know, but even if it were to cost a 10th or 20th... the sum would > be outrageous for T1 or Frame. > > Phil > - Original Message - > From: Kim Seng > To: > Sent: Tuesday, May 08, 2001 2:06 PM > Subject: Wireless for backup T1 link??? [7:3651] > > > > Have anyone experience with Wireless technology for > > backup link solution? I have 2 cities: NY city and LA > > connected via T1 point to point and looking for a > > backup solution that does not cost too much. Is > > wireless is a good solution for this backup? > > > > Thanks! > > > > Kim. > > > > __ > > Do You Yahoo!? > > Yahoo! Auctions - buy the things you want at great prices > > http://auctions.yahoo.com/ > > FAQ, list archives, and subscription info: > http://www.groupstudy.com/list/cisco.html > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=3669&t=3651 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wireless for backup T1 link??? [7:3651]
Use VSAT networks (satellite networks) , contact me if you need this service regards, suaveguru --- Kim Seng wrote: > Have anyone experience with Wireless technology for > backup link solution? I have 2 cities: NY city and > LA > connected via T1 point to point and looking for a > backup solution that does not cost too much. Is > wireless is a good solution for this backup? > > Thanks! > > Kim. > > __ > Do You Yahoo!? > Yahoo! Auctions - buy the things you want at great > prices > http://auctions.yahoo.com/ > FAQ, list archives, and subscription info: > http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] __ Do You Yahoo!? Yahoo! Auctions - buy the things you want at great prices http://auctions.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=3763&t=3651 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
