Transcript CBCR201s10

Policy Propagation
Through BGP
© 2001, Cisco Systems, Inc.
Objectives
Upon completion of this chapter, you will be able to perform
the following tasks:
• Describe the basics of the Differentiated Services QoS
model
• Identify the issues of deploying DiffServ QoS model in
large-scale networks
• Configure and monitor QoS Policy Propagation via BGP
(QPPB)
• Describe the basics of Web Caching
• Identify the issues of deploying differentiated Web
Caching in large-scale networks
• Configure and monitor Web Caching Communication
Protocol (WCCP) Policy Redirection
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-2
Quality of Service
• Accelerating the deployment of network services, by
enabling predictable response for application traffic
and service requirements
• Best-effort IP delivery is not good enough for all
applications and services. Some services or
applications need:
• Guaranteed bandwidth
• Low and predictable delay
• Limited bandwidth
• Requires BGP for propagation of classes of services
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-3
Web Caching
• Used to improve throughput and
response times of frequently visited
web pages
• Requires BGP for advanced web
caching designs with multiple clusters
of web cache devices
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-4
Large-Scale IP Quality of
Service Overview
© 2001, Cisco Systems, Inc.
www.cisco.com
Policy Propagation Through BGP-5
Objectives
Upon completion of this section, you will be
able to perform the following tasks:
• Describe components of the Differentiated
Services (DiffServ) IP QoS model
• Describe the role of IP Precedence in DiffServ
model
• Describe the role of QoS group in Cisco’s QoS
implementation
• List the QoS components deployed between the
Service Provider and a customer
• Identify the challenges of deploying large-scale
QoS solutions
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-6
QoS Conceptual Models
• Two conceptual models developed
within IETF
• Integrated Services (IntServ)
• Differentiated Services (DiffServ)
• IntServ model does not scale
• New IP QoS mechanisms are available
in IOS to support the DiffServ model in
large environments
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-7
DiffServ Overview
• The main goal of DiffServ is to provide a
scalable IP QoS framework
• Defined by IETF’s RFC2475; An architecture
for DiffServ
• Complex traffic classification, marking, and
conditioning is performed at network edge
resulting in a per-packet Differentiated
Services Code Point (DSCP)
• Core only performs ‘simple’ operations based
on DSCP
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-8
Predefined DiffServ Service
Classes
Assured Forwarding
• RFC 2597
• Guarantees bandwidth to a class
• Four standard classes
Expedited Forwarding
• RFC 2598
• Guarantees the lowest possible delay
• One standard class
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-9
QoS Building Blocks within
Cisco IOS
Input
Input
Interface
EDGE: Marking is only performed at
network edge. Based on initial
classification a router can mark IP
packets with DSCP, IP precedence or
QoS group
Meter
Classify
Mark
EDGE: DiffServ model uses
complex classification on
network edges (i.e. access
lists)
CORE: Classification in
the core is based on
DSCP, IP precedence or
QoS group
Police
CORE: Queuing, scheduling
and dropping is influenced
by the simple classification
Forward
Output
Meter
Classify
Mark
Police
Queue
Output
Interface
• Edge classification is the most difficult task in
large environments
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-10
Marking of IP Packets
• IP precedence – high-order three bits in
the Type of Service field in the IP header
• Diffserv Code Point (DSCP) – high order
six bits in DS Field (RFC 2474, former
ToS field)
• QoS group – internal tagging of packets
in routers (requires reclassification on
every hop)
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-11
Class Markers
IP packets in router’s memory are stored in fixed-length “buffers”
Buffer
header
Frame
header
IP
header
IP packet
IP precedence or DSCP
QoS group (information is lost once the
packet leaves the router)
• IP precedence – 3 bits (8 classes)
• DSCP – 6 bits (64 classes)
• QoS group – 100 classes
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-12
QoS Functions
• Guaranteeing quality of service for:
• Applications (usually identified by TCP or
UDP port numbers)
• Services (usually identified by IP addresses
or IP networks)
• Service providers, as the name says,
provide services and can also guarantee
a certain level of quality to these
services
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-13
Example – Classifying
Outgoing Traffic
ISP2
EDGE:
classification is
simple – based on
source interface
EDGE (and CORE):
queuing and
scheduling based on
the marking (IP
precedence or DSCP)
Service
Provider
Customer
• Customer wants guaranteed bandwidth
to and from the Internet (ISP2)
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-14
Example – Classifying
Incoming Traffic
ISP2
EDGE: classification is
impossible in large
networks; using
access list does not
scale
Service
Provider
Customer
• Customer wants guaranteed bandwidth
to and from the Internet (ISP2)
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-15
IP QoS Edge Mechanisms
• Admission control and policing
• Inbound Committed Access Rate (CAR) filters:
per interface, IP ACL, or MAC address
• Packet classification and marking
• CAR filters or BGP-based CEF marking
• Global marking (IP precedence or DSCP field)
• Local marking (QoS group within the router)
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-16
IP QoS Core Mechanisms
Queuing
• Weighted Fair Queuing (WFQ) influenced by IP
precedence
• Class-based WFQ (very fast custom queuing
based on IP precedence or QoS group)
Congestion management
• Weighted Random Early Detection (WRED)
influenced by IP precedence
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-17
Summary
After completing this section, you should be able to
perform the following tasks:
• Describe components of Differentiated Services (DiffServ)
IP QoS model
• Describe the role of IP Precedence in DiffServ model
• Describe the role of QoS group in Cisco’s QoS
implementation
• List the QoS components deployed between the Service
Provider and a customer
• Identify the challenges of deploying large-scale QoS
solutions
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-18
Review Questions
• Name the two predefined DiffServ service
classes
• Name some QoS mechanisms available in the
IOS
• Which QoS markers are available in the IOS?
• How can we mark IP packets with the help of
BGP?
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-19
BGP Driven QoS Marking
© 2001, Cisco Systems, Inc.
www.cisco.com
Policy Propagation Through BGP-20
Objectives
Upon completion of this section, you will be able to
perform the following tasks:
• Describe the Cisco Express Forwarding (CEF) switching
mechanism
• Describe the QoS packet classification and marking with
CEF
• Describe the role of BGP in CEF-based QoS marking
• Configure QoS Policy Propagation with BGP (QPPB)
• Monitor and troubleshoot QPPB
• Deploy QPPB in large-scale BGP-based networks
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-21
QPPB Requirements
QoS Policy Propagation through BGP
requires the following:
• Cisco Express Forwarding (CEF switching)
• BGP
• Cisco 7200, 7500, or 12000
• Cisco IOS release 11.1CC, 12.0, or later
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-22
Review: Standard IP Switching
Address
10.0.0.0
...
BGP Table
IP Routing
Table
Protocol
BGP
conn.
Switching
Cache
Address
10.0.0.0
...
IP address
1.2.3.4
ARP Cache
...
© 2001, Cisco Systems, Inc.
Prefix
/8
...
Address
10.0.0.0
1.2.3.0
Prefix
/8
...
AS-Path
42 13
...
Prefix
/8
/24
Next hop
1.2.3.4
...
Next-hop
1.2.3.4
---
Communities
37:12
...
Other attr.
...
Outgoing interface
--Ethernet 0
L2 header
MAC header
...
MAC address
0c.00.11.22.33.44
...
Policy Propagation Through BGP-23
Review: CEF Switching
Address
10.0.0.0
...
BGP Table
IP Routing
Table
Protocol
BGP
OSPF
conn.
Address
10.0.0.0
...
FIB Table
(CEF
Cache)
Adjacency
Table
IP address
1.5.4.1
...
© 2001, Cisco Systems, Inc.
Prefix
/8
...
Address
10.0.0.0
1.2.3.0
1.5.4.0
Prefix
/8
...
AS-Path
42 13
...
Prefix
/8
/24
/24
Next hop
1.2.3.4
...
Next-hop
1.2.3.4
1.5.4.1
---
Communities
37:12
...
Other attr.
...
Outgoing interface
--Ethernet 0
Ethernet 0
Adjacency pointer
1.5.4.1
...
Layer 2 header
MAC header
...
IP address
1.5.4.1
...
ARP cache
MAC address
0c.00.11.22.33.44
...
Policy Propagation Through BGP-24
CEF Switching with QoS
Packet Marking
BGP Table
Address
10.0.0.0
...
Prefix
/8
...
AS-Path
42 13
...
Next hop
1.2.3.4
...
Communities
37:12
...
Other attr.
...
BGP table map
IP Routing
Table
FIB Table
(CEF
Cache)
Adjacency
Table
Protocol
BGP
OSPF
conn.
Address
10.0.0.0
...
IP address
1.5.4.1
...
© 2001, Cisco Systems, Inc.
Address
10.0.0.0
1.2.3.0
1.5.4.0
Prefix
/8
...
Prefix
/8
/24
/24
Next-hop
1.2.3.4
1.5.4.1
---
Adjacency pointer
1.5.4.1
...
Layer 2 header
MAC header
...
Outgoing interface Precedence QoS group
--3
7
Ethernet 0
----Ethernet 0
-----
Precedence QoS group
7
3
...
...
ARP cache
IP address
MAC address
1.5.4.1
0c.00.11.22.33.44
...
...
Policy Propagation Through BGP-25
QoS Packet Marking with CEF
• Mark the routes in the BGP table
• Use BGP communities, AS paths, IP prefixes,
or any other BGP attributes
• Set IP precedence or QoS group in IP
routing table and FIB table
• Enable CEF packet marking on interface
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-26
Set IP Precedence or QoS Group
in the IP Routing Table and FIB
Router(config-router)#
table-map route-map-name
• Specifies the route map used to set additional
routing table attributes
Router(config)#
route-map name permit seq
set ip precedence precedence
set ip qos-group group
• Specifies IP precedence and QoS group values in
the routing table/FIB table entry
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-27
Enable Per-Interface Packet
Marking
Router(config-if)#
bgp-policy source ip-prec-map
• Applied to packets received through this interface
• Uses FIB to map packet source IP address to IP
precedence
• Rewrites IP precedence in the packet
Router#
bgp-policy source ip-qos-map
• Applied to packets received through this interface
• Uses FIB to map packet source IP address to QoS
group
• QoS group attached to the incoming packet
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-28
Enable Per-Interface Packet
Marking (cont.)
Router(config-if)#
bgp-policy destination ip-prec-map
• Applied to packets received through this interface
• Uses FIB to map packet destination IP address to IP
precedence
• Rewrites IP precedence in the packet
Router#
bgp-policy destination ip-qos-map
• Applied to packets received through this interface
• Uses FIB to map packet destination IP address to
QoS group
• QoS group attached to the incoming packet
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-29
Monitoring and
Troubleshooting QPPB
router#
show ip cef [prefix] [detail]
• Detailed CEF output shows the IP precedence value
Router#show ip cef 10.1.1.0 detail
10.1.1.0/24, version 12, cached adjacency to Serial0/0.1
0 packets, 0 bytes, Precedence flash (3)
via 10.3.0.2, 0 dependencies, recursive
next hop 10.3.0.2, Serial0/0.1 via 10.3.0.0/30
valid cached adjacency
Router#
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-30
Monitoring and
Troubleshooting QPPB (cont.)
router#
show ip interface [interface]
• Shows whether QPPB is enabled on an interface
Router#show ip interface
Serial0 is up, line protocol is up
Internet address is 10.3.0.2/30
Broadcast address is 255.255.255.255
...
Policy routing is disabled
Network address translation is disabled
WCCP Redirect outbound is disabled
WCCP Redirect inbound is disabled
WCCP Redirect exclude is disabled
BGP Policy Mapping is enabled (output ip-prec-map)
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-31
IP QoS Case Study
WAN Core
NAP Router
AS 24
NAP Router
POP Router
AS 12
Customer
(AS 73)
• Customer in AS 73 is a Premium customer
• All packets to and from AS 73 shall be sent
with precedence flash
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-32
Step #1
Distribute QoS Functions
WAN Core
NAP Router
NAP Router
AS 24
POP Router
AS 12
Customer
(AS 73)
Packets for AS73
marked with
precedence flash
Packets from serial
interface marked with
precedence flash
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-33
Step #2
Select QoS Mechanisms
WAN Core
NAP Router
POP Router
NAP Router
AS 24
AS 12
Customer
(AS 73)
CEF-based marking
Packets for AS73
marked with
precedence flash
Inbound CAR filter on interface
Packets from serial
interface marked with
precedence flash
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-34
Step #3 - Design Individual QoS
Mechanisms (CEF Marking)
Mark BGP routes from AS 73
with special community (12:17)
Configure community propagation
WAN Core
NAP Router
AS 24
NAP Router
POP Router
Customer
AS Set
12 FIB table(AS
73) on
based
BGP community
Configure CEF packet marking
for packets coming from adjacent AS
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-35
Mark Routes Coming from
AS73
WAN Core
NAP Router
AS 24
NAP Router
POP Router
AS 12
Customer
(AS 73)
router bgp 12
neighbor 1.2.3.4 remote-as 73
neighbor 1.2.3.4 route-map Premium in
!
route-map Premium permit 10
set community 12:17 additive
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-36
Configure Community
Propagation
WAN Core
NAP Router
NAP Router
AS 24
POP Router
AS 12
Customer
(AS 73)
router bgp 12
neighbor 2.3.4.5 remote-as 12
neighbor 2.3.4.5 send-community
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-37
Set FIB Table Based on BGP
Community
WAN Core
NAP Router
AS 24
© 2001, Cisco Systems, Inc.
NAP Router
POP Router
Customer
router bgp 12
AS 12
(AS 73)
table-map PremiumCheck
!
route-map PremiumCheck permit 10
match community 17
set ip precedence flash
!
route-map PremiumCheck permit 20
set ip precedence 0
!
ip community-list 17 permit 12:17
Policy Propagation Through BGP-38
Configure CEF Packet Marking
WAN Core
NAP Router
AS 24
NAP Router
POP Router
AS 12
Customer
(AS 73)
ip cef switch
!
interface hssi 0/0
bgp-policy destination ip-prec-map
ip route-cache cef
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-39
IP QoS and BGP Interaction
Review
• IP QoS features work independently of
BGP routing
• BGP is used only to propagate policies
for source or destination IP prefixes
through the network
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-40
Summary
After completing this section, you should be able to
perform the following tasks:
• Describe the Cisco Express Forwarding (CEF) switching
mechanism
• Describe the QoS packet classification and marking with
CEF
• Describe the role of BGP in CEF-based QoS marking
• Configure QoS Policy Propagation with BGP (QPPB)
• Monitor and troubleshoot QPPB
• Deploy QPPB in large-scale BGP-based networks
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-41
Review Questions
• What is a FIB table?
• How is BGP information translated into QoS
information in the FIB table?
• Describe the configuration steps for QPPB
• How many CEF lookups are performed for
each packet when QPPB is enabled?
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-42
Overview of Web Caching in
Large Networks
© 2001, Cisco Systems, Inc.
www.cisco.com
Policy Propagation Through BGP-43
Objectives
Upon completion of this section, you will be able to
perform the following tasks:
• Describe Web Caching components
• Describe the need for differentiated Web Caching behavior
• Identify the challenges of deploying differentiated Web
Caching behavior in large-scale networks
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-44
What is Web Caching?
• Web Caching is a technology used
primarily to intercepts HTTP requests
and serve them locally
• A web cache stores the information for
further requests for the same content
• Web Cache Communication Protocol
(WCCP) is a protocol used between a
router and a web cache
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-45
Web Caching Example
Redirect
http://acme.com
http://acme.com
Web
Server
www.acme.com
W
W
W
W
W
W
Web Cache
• Access to non-cached web page
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-46
Web Caching Example (cont.)
Redirect
Web
Server
W
W
The web cache device
only needs to validate
the web page
W
W
W
W
www.acme.com
Web Cache
• Access to cached web page
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-47
Why Web Caching?
ISP2
Not enough
bandwidth to
accomodate all
requests
Poor response times
because of congestion
and distance
Service
Provider
• Among a large number of HTTP requests, many target a small
number of most visited web pages
• Using a web cache can improve throughput and response times
• Estimate: 70% is web traffic and 50% of it is duplicate
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-48
Web Cache Design Options
• What to cache:
• which sources or destinations should be serviced by a
caching device;
• which applications should be serviced by a caching device
- WCCP version 2 supports port numbers other than 80
• Where to cache (at ingress, egress or both)
• Do we need to provide differentiated quality of
service for web traffic originating from customers
using different classes of service
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-49
Where to cache
ISP2
WW
W
WW
WW
W
WW
A service provider
may deploy a small
number of caching
devices on egress
points (close to
NAPs)
Service
Provider
A service provider
may deploy a large
number of caching
devices on ingress
points (POPs)
Customers
may use their
own caching
devices or
proxies
WW
W
WW
WW
W
WW
WW
W
WW
WW
W
WW
WW
W
WW
WW
W
WW
A service provider may
deploy caching in front of
its web server farm to
offload static content to
caching devices
Customer
• Caching should be implemented as close to the source (customer or
web server farm) as possible
• Caching devices may be located further away form the source (i.e. due
to cost involved with a large number of caching devices)
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-50
Differentiated Web Caching
• WCCP design options:
• Caching for all users
• Caching for some users (requires an access list)
• Grouping users into caching clusters (requires
multiple access lists)
• The first option is simple to configure
• The other two require access lists to identify
users. It is difficult to maintain accurate
access lists and is, therefore, not scalable
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-51
Summary
After completing this section, you should be able to
perform the following tasks:
• Describe Web Caching components
• Explain the need for differentiated Web Caching behavior
• Identify the challenges of deploying differentiated Web
Caching behavior in large-scale networks
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-52
Review Questions
• What is the purpose of web caching?
• How can web caching affect other QoS
features implemented in a network?
• What is WCCP?
• What are the problems of setting up standard
web caching?
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-53
WCCP Policy Redirection
© 2001, Cisco Systems, Inc.
www.cisco.com
Policy Propagation Through BGP-54
Objectives
Upon completion of this section, you will be able to
perform the following tasks:
• Describe the differentiated Web Caching mechanism
controlled by the BGP table
• Configure WCCP Policy Redirection
• Monitor and troubleshoot WCCP Policy Redirection
• Deploy WCCP Policy Redirection in large-scale BGP-based
networks
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-55
WCCP Policy Redirection
• BGP provides a scalable solution for
classifying packets and Web Cache users
• There may be multiple classes of networks
assigned to different web caching clusters
• Web cache clusters may have different
services enabled
• Web cache clusters may have different QoS
guarantees
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-56
Customer Driven WCCP Policy
Redirection
WW
W
WW
10/8 12:10
10/8 12:10
WAN Core
NAP Router
NAP Router
AS 24
BGP community 12:10
is translated into
internal WCCP tag 1
POP Router
AS 12
Customer
(AS 73)
Customers network
carries BGP
community 12:10
• A decision whether to use a web cache can be left to a
customer
• A customer can use BGP communities to choose the caching
option
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-57
Provider Driven WCCP Policy
Redirection
WW
W
WW
10/8 12:10
10/8
WAN Core
NAP Router
NAP Router
AS 24
BGP community 12:10
is translated into
internal WCCP tag 1
POP Router
AS 12
Customer
(AS 73)
A service provider assigns
a customer to a class
according to an SLA
• A decision whether to use a web cache for a specific
customer is determined by the ISP according to the SLA
• The service provider sets the appropriate BGP community
attribute
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-58
Configuring WCCP Policy
Propagation
Router(config)#
route-map name permit seq
match ...
set ip wccp policy-tag
• Set the policy tag within a route map
Router(config-router)#
table-map name
• Apply a route map to updates going from the BGP
table into the routing table
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-59
Configuring WCCP Policy
Propagation (cont.)
Router(config)#
ip wccp version 2
• WCCP policy redirection works if WCCP version 2
is used
Router(config)#
ip wccp web-cache policy {source | destination} policy-tag
or
ip wccp service-tag policy {source | destination} policy-tag
• Enables web caching for packets with source or
destination matched in the FIB table if the packets
have corresponding policy tags
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-60
Configuring WCCP Policy
Propagation (cont.)
Router(config-if)#
ip wccp web-cache redirect {in | out}
or
ip wccp service-tag redirect {in | out}
• Enables web caching on an interface
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-61
Monitoring WCCP Policy
Redirection
router#
show ip cef [prefix] [detail]
• Detailed CEF output shows WCCP tags
Router#show ip cef 10.1.1.0 detail
10.1.1.0/24, version 35, cached adjacency to Serial0/0.1
0 packets, 0 bytes, wccp tag 1
via 10.3.0.2, 0 dependencies, recursive
next hop 10.3.0.2, Serial0/0.1 via 10.3.0.0/30
valid cached adjacency
Router#
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-62
Monitoring WCCP Policy
Redirection (cont.)
router#
show ip interface [interface]
• Shows whether WCCP is enabled on an interface
Router#show ip interface
Serial0 is up, line protocol is up
Internet address is 10.3.0.2/30
Broadcast address is 255.255.255.255
...
Policy routing is disabled
Network address translation is disabled
WCCP Redirect outbound is enabled
WCCP Redirect inbound is disabled
WCCP Redirect exclude is disabled
…
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-63
WCCP Policy Redirection
Case Study
• A service provider has three types of users:
• Dial-up users
• Best-effort users
• Premium users
• Each group is assigned to a separate cluster
of web cache devices
• A Premium customer is allowed to disable
web caching
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-64
Case Study - Design
Service
BGP Community
Dial-up Users
387:1x0x
Best Effort Users
387:1x1x
Premium Users
387:1x2x
No Caching
387:1x3x
• The service provider uses four digits in BGP communities
• The third digit is used for web caching options
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-65
Case Study – Network Layout
WCCP Policy
Redirection based
on BGP
communities
ISP2
AS 387
W
W
W
W
W
W
W
W
W
W
W
W
Dial-up pools are
inserted into BGP
and marked with
387:1000
© 2001, Cisco Systems, Inc.
W
W
W
W
Premium
customer is
marked with
387:1020 if not
already marked
with 387:1030
W
W
Premium
Customer
PSTN /
Best-effort
ISDN
customer is
marked with
387:1010
Besteffort
Customer
Policy Propagation Through BGP-66
Case Study – Dial-up Users
ip local pool DIALUP 192.168.10.1 192.168.10.254
ip route 192.168.10.0 255.255.255.0 null 0
!
router bgp 387
network 192.168.10.0 route-map SetCommunity
!
route-map SetCommunity permit 10
set community 387:1000
AS 387
!
ISP2
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
Premium
Customer
PSTN /
ISDN
© 2001, Cisco Systems, Inc.
Besteffort
Customer
Policy Propagation Through BGP-67
Case Study – Best-effort Users
ip route 200.200.200.0 255.255.255.0 serial 0 tag 1010
!
router bgp 387
redistribute static route-map BestEffort
!
route-map BestEffort permit 10
match tag 1010
set community 387:1010
AS 387
set origin igp
!
ISP2
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
Premium
Customer
PSTN /
ISDN
© 2001, Cisco Systems, Inc.
Besteffort
Customer
Policy Propagation Through BGP-68
Case Study – Premium Users
! Static Premium Customer
ip route 150.1.1.0 255.255.255.0 serial 0 tag 1020
!
ISP2
router bgp 387
redistribute static route-map Premium
neighbor 192.168.1.2 remote-as 65001
neighbor 192.168.1.2 description BGP Premium
neighbor 192.168.1.2 route-map Premium in
AS 387
!
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
route-map StaticPremium permit 10
match tag 1020
set community 387:1020
set origin igp
!
route-map BGPPremium permit 10
match community 120
!
route-map BGPPremium permit 20
set community 387:1020
!
ip community-list 120 permit _387:..3._
Premium
Customer
PSTN /
ISDN
© 2001, Cisco Systems, Inc.
Besteffort
Customer
Policy Propagation Through BGP-69
Case Study – Policy
Redirection
ISP2
W
W
W
W
W
W
© 2001, Cisco Systems, Inc.
W
W
W
W
W
W
router bgp 387
table-map WCCP_PP
!
route-map WCCP_PP permit 10
match community 100
set ip wccp 1
!
route-map WCCP_PP permit 20
match community 101
AS 387
set ip wccp 2
!
route-map WCCP_PP permit 30
match community 102
set ip wccp 3
!
route-map WCCP_PP permit 1000
!
ip community-list
100 permit _387:..0._
PSTN /
ip community-list 101 permit _387:..1._
ISDN
ip community-list
102 permit _387:..2._
W
W
W
W
W
W
ip cef
!
ip wccp version 2
ip wccp 1 policy source 1
ip wccp 2 policy source 2
ip wccp 3 policy source 3
!
interface hssi1/0
ip wccp 1 redirect out
ip wccp 2 redirect out
ip wccp 3 redirect out
!
Premium
Customer
Besteffort
Customer
Policy Propagation Through BGP-70
Summary
After completing this section, you should be able to
perform the following tasks:
• Describe the differentiated Web Caching mechanism
controlled by the BGP table
• Configure WCCP Policy Redirection
• Monitor and troubleshoot WCCP Policy Redirection
• Deploy WCCP Policy Redirection in large-scale BGP-based
networks
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-71
Review Questions
• What is the purpose of using BGP for WCCP
policy propagation?
• What is a WCCP tag?
• What is the relation between BGP attributes
and WCCP tags?
• List the configuration steps to enable WCCP
based on BGP attributes.
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-72
Summary
After completing this chapter, you should be able to
perform the following tasks:
• Describe the basics of the Differentiated Services QoS
model
• Identify the issues of deploying DiffServ QoS model in
large-scale networks
• Configure and monitor QoS Policy Propagation via BGP
(QPPB)
• Describe the basics of Web Caching
• Identify the issues of deploying differentiated Web Caching
in large-scale networks
• Configure and monitor Web Caching Communication
Protocol (WCCP) Policy Redirection
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-73
© 2001, Cisco Systems, Inc.
Policy Propagation Through BGP-74