TCP UDP small servers

This is used for diagnostics.
enabled by
# service tcp-small-servers
# service udp-small-servers

TCPIP NAGLE Algorithms

when a file is send over a network, its chopped as packets .
Now think we use TCPIP for transmission , as per tcp mechanism it requires ack for every packets send.
It's imp that sender wont flood receiver and receiver won't flood sender .
But as per above mechanism of tcp chances for flooding.

NAGLE algorithms is used for congestion control
--
when a sender sends packet , it will wait for ack to send following.It's bandwidth saving feature for keystroke based applications ( telnet )
Default disabled on Cisco routers
To enable it on router
# service nagle

Delayed ack algorithm is also used for congestion control
--
This is to control ack messages . When a packet receives , receiver should send ack.
But as per algorithms it waits 200ms or 2 ack to see if any more packets are coming , so tht it can send as single ack.

itiot's blog

i was, bit lazy after i start this blog, now ack to study for my ccie.
will blog everything what i study,.
Now going for dinner and sleep.see you guys tmrw morng. sweet dreams nation

itiot's blog

i was, bit lazy after i start this blog, now ack to study for my ccie.
will blog everything what i study,.
Now going for dinner and sleep.sPublish Postee you guys tmrw morng. sweet dreams nation

itiot's blog

i was, bit lazy after i start this blog, now ack to study for my ccie.
will blog everything what i study,.
Now going for dinner and sleep.see you guys tmrw morng. sweet dreams nation

Querier, PIM-Desginated router , PIM forwarder

1 )the router with lowset IP address becomes IGMP v2 querier

( igmpv2 router sees same query on wire ( normally happens on Multi access networks , it compares and lowset wins Loser cease sending query and listens all time , if querier dead it will take over responsibilty for sending query )

2 ) the router with highest IP becomes PIM desginated router.Very imp in IGMP v1

In IGMP v1 PIM Desgnated router responsible for 2 things

a ) for sending pim register , pim join/prune

b ) for sending query messages

in IGMP v2 its decoupled

querier only sends query , pim DR forwards muticast

3 ) PIM forwarder : if same muticast packet comes on mutiaccess networks only one router will forward.

A ) first checks AD to source ( prefer lowset AD )

if both uses same protocol like ospf AD will be same

B ) checks Metric towrds source address. ( lowset preferred )

we can check both this via # show ip route

C)Next highest IP is preferred.

Bottom Tip : if both router running IGMPv2 , there is no importance for PIM -DR

uses straightthrough and cross over cables

The following use cross-over
switch <-> Switch (dce to dce)
switch<-> Hub
PC <-> PC (dte to dte)
PC <-> Router (dte to dte)
Router<->Router (via ethernet)

Straight-through

Switch<->PC
Switch<->Router


roll over is for console access switches , routers etc
This wont transfer data,