Regreso al estudio 2012 !!!

:-) La semana pasada volvi armar mi rack de equipos que tenia abandonado casi un año. Buenos recuerdos volvieron mientras lo hacia.

Faltan dos 2610 que done al colegio donde dicte clases de Networking, pienso comprarme unos 2620XM u otros mejores.

Hoy puse a funcionar Gracias a Dios el Terminal Server Equinox, la documentacion que habia puesto en este blog el año pasado me facilito las cosas, ya tengo acceso remoto a las consolas de los SW y RO desde la comodidad de mi cama :-)

PAgP Silent or Non-Silent Mode

Silent/Non-Silent Mode

When you deal with fiber connections, there is a possibility that, even if a receive (Rx) transceiver dies, the transmit (Tx) transceiver on the other end is still up. In a similar scenario, packets can get black holed.

It is important for the switch that transmits to remove this port from the EtherChannel bundle. In order to do so on the Catalyst 5500/5000, you set PAgP in non-silent mode. Non-silent mode means that, if the Rx does not receive traffic, the port is not put into the channel. However, use of non-silent mode is not enough because this detection happens only when the channel is formed.

In order to prevent the black holing of traffic when the channel is already formed, this occurs:

1. PAgP detects that the Rx port does not receive any traffic.
2. PAgP resets the Tx transceiver of the port that does not receive traffic. PAgP resets it for 1.6 seconds so that the switch on the other end also resets the port.
3. The faulty port does not join the channel anymore because no traffic is received on that port.

On the Catalyst 5500/5000, set non-silent mode on fiber strands and silent mode on copper strands. This is both the default and recommended setting because, on fiber connections on the Catalyst 5500/5000, the negotiation is usually not available, so there is no way to detect the problem at a physical layer.

Default PAgP Settings on the Catalyst 4500/4000 and 5500/5000

By default, PAgP is auto for a plug-and-play implementation. Disable PAgP manually from the ports where there is no need to have it.

By default, the silent mode is on. Non-silent is acceptable as well. However, because a port can be connected to a device that does not send traffic (for example, a sniffer), it is more general to have silent enabled.

Recommendations

• Use the non-silent keyword when you connect to a device that transmits bridge protocol data units (BPDUs) or other traffic. Use this keyword with the auto or desirable mode. PAgP non-silent adds an extra level of link state detection because it listens for BPDUs or other traffic in order to determine if the link functions properly. This adds a form of UniDirectional Link Detection (UDLD) capability that is not available when you use the default silent PAgP mode.
• Use the silent keyword when you connect to a silent partner (which is a device that does not generate BPDUs or other traffic). An example of a silent partner is a traffic generator that does not transmit packets. Use the silent keyword with auto or desirable mode. If you do not specify silent or non-silent, silent is assumed.
• The silent mode does not disable the PAgP ability to detect unidirectional links. However, when you configure a channel, non-silent prevents a unidirectional port from even joining the link.
• A PAgP configuration (the set port channel {desirable | auto} command) is safer than a non-PAgP configuration (the set port channel on command). A PAgP configuration provides protection for unidirectional links and also avoids misconfigurations that can arise when there are ports channeling on one side of the link and not on the other side.
• Refer to Understanding and Configuring the Unidirectional Link Detection Protocol Feature for more information on UDLD.

PAgP combinations

La siguiente tabla la consegui en este link que se los recomiendo: http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a00800949c2.shtml#pagptoconfig

Switch A Channel Mode	Switch B Channel Mode	Switch A Channel State	Switch B Channel State
on	on	Channel (non-PAgP)	Channel (non-PAgP)
on	off	Not channel (errdisable)	Not channel
on	auto	Not channel (errdisable)	Not channel
on	desirable	Not channel (errdisable)	Not channel
off	on	Not channel	Not channel (errdisable)
off	off	Not channel	Not channel
off	auto	Not channel	Not channel
off	desirable	Not channel	Not channel
auto	on	Not channel	Not channel (errdisable)
auto	off	Not channel	Not channel
auto	auto	Not channel	Not channel
auto	desirable	Channel (PAgP)	Channel (PAgP)
desirable	on	Not channel	Not channel (errdisable)
desirable	off	Not channel	Not channel
desirable	auto	Channel (PAgP)	Channel (PAgP)
desirable	desirable	Channel (PAgP)	Channel (PAgP)

TRUNK LIKS

802.1Q introduce el concepto de VLAN nativa sobre una troncal. Los frames pertenecientes a
esta VLAN no son encapsulados con cualquier información marcada. Si en una end-station esta  conectada a un un trunk-link 802.1q, la end-station puede recibir y comprender solamente los frames de la VLAN nativa. Esto proporciona una forma sencilla de ofrecer full-trunk-encapsulation a los dispostivos que lo pueden comprender, y al mismo tiempo las end-statiosn tienen acceso a  conectividad inherente sobre la troncal.

VLAN's

Las VLAN's Virtual LANS tienen varias clasificaciones:

STATIC: son creadas y los puertos asignadas manualmente
DYNAMIC: son administradas por medio de VMPS VLAN-Membership-Policy-Server

STANDARD: van de 1 a 1005, siendo 1, 1002 a 1005 VLAN reservadas
EXTENDED: van de 1 a 4094 pero solo pueden cofigurarse en SW's en TRANSPARENT MODE

END-TO-END: llamadas tambien campuswide VLANs, el concepto principal de esta definicion es que el trafico de la VLAN debe estar manejado por las capas: ACCESS y DISTRIBUTION siguiendo la regla de trafico 80/20
LOCAL: son usadas por empresas que manejan la regla de trafico 20/80

Felices Pascuas...!!!

Repasando

Hola, estuve un poco desconectado del estudio, por eso ahora estoy repasando el capitulo 2. Les dejo un mensaje que aprendi durante la desconexion.