OSPF

LSA TypeAdvertising RouterRouting TableDBSummaryFilterComments
1 - Router (Intra Area)AllOsh ip ospf data routerLists neighbouring routers and the cost to each (flooded within an area)
2 - Pseudonode (Intra Area)DROsh ip ospf data networkGenerated by DR it lisst all routers on an adjacent segment (flooded within an area)
3 - Network Summary (Inter Area)ABRIAsh ip ospf data summaryGenerated by an ABR and advertised among areas
4 - ASBR Summary (Inter Area) ABRN/Ash ip ospf data asbr-summary Injected by an ABR into the backbone to advertise the presence of an ASBR within an area.
(not really used anywhere)
5 - External Link (External)ASBRDefault = E2
Can be E1
sh ip ospf data external
Generated by an ASBR and flooded throughout the AS to advertise a route external to OSPF
6 - MOSPFN/AN/AN/A Not supported with Cisco
7 - NSSA External Link(External)ASBR in NSSADefault = N2
Can be N1
sh ip ospf data nssa-externalGenerated by an ASBR in a not-so-stubby area; converted into a type 5 LSA by the ABR when leaving the area
LSA types 1 and 2 are found in all areas, and are never flooded outside of an area. Whether the other types of LSAs are advertised within an area depends on the area type
If a tie between OSPF routes, then O > O*IA > E1 > E2.
OSPF : Can’t establish neighbors on secondary IP’s, secondary networks are seen as stub-networks.

- OSPF External Type1 (E1) routes

  • Include the external cost as well as the internal cost to the ASBR.
  • Used to exit the AS as close as possible to the destination.
  • Mostly used if multiple exit points out an AS exist.

- OSPF External Type2 (E2) routes:

  • Include only the external cost of the route.
  • Used to exit the AS via closest ASBR.
  • Often used with only one OSPF exit point.

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VTP

The VTP password can be done in 3 places;

  • privilege mode
  • vlan database
  • global config mode

VTP can be configured under the VLAN database;

vlan database
  vtp domain CCIE
  exit
Mar 23, 2011 - Certification, Networking    No Comments

QoS – AutoQoS VoIP

Can be applied to either a router or switch

CLI;

  • router(config-if)# auto qos voip   # enable and configure  it on the interface
  • router(config-if) or (config-fr-dlci)# auto qos voip [trust] [fr-atm] # configures the AutoQoS feature (untrusted by default) on routers
  • console> (enable) set qos autoqos       #turn on global QoS settings in CatOS
  • console> (enable) set port qos <mod/port> autoqos trust [cos|dscp] #CatOS specific interface configuration
  • console> (enable) set port qos <mod/port> autoqos voip [ciscosoftphone|ciscoipphone]         #When phones are attached
  • switch(config-if)# auto qos voip trust         #uplink interface connected to a trusted switch or router
  • switch(config-if)# auto qos voip cisco-phone         #enables a trusted boundary which uses CDP to detect the IP phone Read more »

QoS – MQC

The modular QoS CLI (MQC).

  • MQC step 1 allows us to create various classifications (class map)
  • MQC step 2 allows us to create a policy (Policy Map)
  • MQC step 3 apply a policy to an interface (inbound or outbound) (Service Policy)

Class Maps;

categories of traffic

contains 3 major elements; case sensitive name, match commands & instruction on how to evaluate these match commands

Class maps can operate in 2 modes

  • Match all (this is the default match)
  • Match any

Configuring class maps;

  • router(config)# class-map [match-all | match-any] <class-map-name>
  • router(config-cmap)# match <condition>             # use at least one condition to match packets
  • router(config-cmap)# description <description>
  • router(config-cmap)# match not <condition>    # the not keyword inverts the condition
  • router(config-cmap)# match class-map <class-map-name>   # a class map can use another for classification
  • router(config-cmap)# match any            # can be used to match all packets

show class-map [class-map]

Configuring policy maps;

  • router(config)# policy-map <policy map name>
  • router(config-pmap)# class {class-name | class-default}    #enter the per class policy configuration mode
  • router(config-pmap)# class <class-map-name> condition # optionally you can define a new class map by entering the condition after the name  of the new class-map
  • router(config-pmap)# description <description>
  • router(config-pmap-c)#<PHB mechanism>    # Per-class service policies are configured with in the per-class policy-map configuration mode. MQC supports CBFWQ, Low-latency queueing, class-based policing, class-based shaping, class-based marking.
  • router(config-pmap-c)# service-policy <policy -map-name>   # policy maps usually applied to interfaces but nested policy maps can be applied directly inside other policy maps to influence seq of QoS actions.

show policy-map [policy-map]

show policy-map interface <int name> [input|output]

Configuring service-policy;

  • router(config-if)# service-policy {input | output} <policy-map-name>

QoS – AutoQoS Enterprise

AutoQoS Enterprise not just focused on VoIP but also video and data traffic (up to 10 classes of traffic – Cisco Best practice).

Typically for medium sized companies

CLI;

  • router(config-if) or (config-fr-dlci)# auto discovery qos [trust]   #configures the discovery phase by gathering stats via NBAR
  • router(config-if) or (config-fr-dlci)# auto qos     # this command will not work until stats have been gathered, it instructs the templates generated to be applied.
  • #show auto qos [interface <interface>]     # displays created configuration
  • #show auto discovery qos        #displays what AutoQoS has discovered

Before AutoQoS Enterprise recommends any policy it needs to monitor the traffic to understand network and traffic patterns

Before configuring (applying a sugested policy) you must remove any existing policies on the interface

CEF needs to be enabled on the router (needed for NBAR to run)

Correctly state the interaface bandwidths

QoS – InetServ

Uses RSVP to revers bandwidth

Service garantee is end-to-end

Can perform CAC

RSVP uses various mssage types to setup;

  • PATH Message (from the initiator)
  • RESV Messgage (back towards the sender)
  • TEARDOWN Messgae (from either sender or reciever)

There are 3 types of QoS services offered by RSVP,

  • Best-effort (FIFO, so not really QoS)
  • Guranteed rate
  • Controlled load (form of CAC)

RSVP works in both control plane and data plane. In the control plane the job of RSVP is CAC (permit or deny reservation request). In the data plane function give priority to traffic (WRED, WFQ) with scheduling and policing. RSVP has very high priority on the data plane.

  • router(config-if)# ip rsvp bandwidth [interface-kbps] [single flow kbps]           #Enables RSVP
  • router(config-if)# ip rsvp resource-provider none      #Disables Reserving Interface resources
  • router(config-if)# ip rsvp data-packet classification none      #Disables Packet Classification

IntServ and DiffServ can intergrate together.

QoS – Implementing/notes

Methods to implement QoS;

  • CLI
  • MQC
  • AutoQoS VoIP (voice QoS)
  • AutoQoS Enterprise (voice, video and data QoS)
  • QPM

MQC (Modular QoS CLI) proccess

  1. Classify traffic
  2. Whats going to happen to the classes of traffic
  3. Assign to interface

AutoQoS VoIP CLI - auto qos voip [trust]

AutoQoS Enterprise CLI – auto discovery qos [trust] & quto qos

IntServ (intergrated Services) used RSVP to allocate an amount of bandwidth. While app has bandwidth reserved no other app can use it. All hops need to be configured to allow IntServ to work.

DiffServ – Differaniates between traffic . Can give differant levels of priority by marking them differantly. Its highly scalable and granular with many levels possible however no absolute service garantee and can have complex mechnisms.

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