Multicast中有关RP的配置问题（I）
发信人: ietobe(ietobe)
整理人: ietobe(2001-09-09 23:24:39), 站内信件
This purpose of this paper is to outline the possible ways to configure
an RP for a Protocol Independent Multicast Sparse Mode network. It will
include basic configurations and explanations of each option.
The Configuration options are as follows:
1. Static RP—sparse-mode
2. Auto-RP—1 RP—sparse-dense
3. Auto-RP—2 RPs—sparse-dense
4. BSR—1 RP—sparse-mode
5. BSR—2 RPs—sparse-mode
6. Anycast—static—sparse-mode
7. Anycast—Auto-RP—sparse-dense
8. Anycast—BSR
9. Static—Auto-RP—sparse-mode
10. Anycast—Auto-RP—sparse-mode
The network used in these configurations is shown in Figure 1.
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Note All configurations include only the relevant multicast commands.
It is required that unicast routing be configured and stable before
adding these configurations.
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Figure 1:
Network Diagram
75a
interface Loopback0
ip address 20.0.0.2 255.255.255.255
interface Loopback1
ip address 20.0.0.1 255.255.255.255
72a
interface Loopback0
ip address 20.0.0.3 255.255.255.255
interface Loopback1
ip address 20.0.0.1 255.255.255.255
1. Static RP—sparse-mode
This is the SIMPLEST way to configure Sparse Mode IP Multicast. It is
easy to configure and troubleshoot in a SMALL network, but can be laborious
in a large complex network. The disadvantages include requiring the
network administrator to configure all leaf routers with the RP's information
and HAVING TO REPEAT THIS TASK if the RP is ever changed. As there is
only one RP PER GROUP, we have a single point of failure for all groups.
Each group can have a separate RP, but this increases the likelihood
of misconfiguration and does not add to redundancy only load balancing.
The Routers are manually configured with the address of the RP and
the interfaces are configured in sparse mode.
ip pim rp-address
ip pim sparse-mode
Strengths and Weakness of Static RP—sparse-mode
Convergence: Excellent Redundancy: Poor Ease of use: Poor in all but
the simplest networks Scoping: Excellent Safety: Excellent Load balancing:
Poor
Configurations for Static RP—sparse-mode
36a
ip multicast-routing
interface Ethernet0/1
ip address 20.0.7.6 255.255.255.0
ip pim sparse-mode
interface FastEthernet2/0
ip address 20.0.6.6 255.255.255.0
ip pim sparse-mode
ip pim rp-address 20.0.0.2
36b
ip multicast-routing
interface Ethernet0/1
ip address 20.0.7.7 255.255.255.0
ip pim sparse-mode
interface Ethernet1/0
ip address 20.0.10.7 255.255.255.0
ip pim sparse-mode
interface FastEthernet2/0
ip address 20.0.8.7 255.255.255.0
ip pim sparse-mode
ip pim rp-address 20.0.0.2
36c
ip multicast-routing
interface Serial0/0
ip address 20.0.9.10 255.255.255.0
ip pim sparse-mode
interface Ethernet0/1
ip address 20.0.10.10 255.255.255.0
ip pim sparse-mode
interface FastEthernet1/0
ip address 20.0.3.10 255.255.255.0
ip pim sparse-mode
ip pim rp-address 20.0.0.2
36d
ip multicast-routing
interface Serial0/0
ip address 20.0.9.11 255.255.255.0
ip pim sparse-mode
interface Ethernet0/1
ip address 20.0.5.11 255.255.255.0
ip pim sparse-mode
ip pim rp-address 20.0.0.2
72a
ip multicast-routing
interface Loopback0
ip address 20.0.0.3 255.255.255.255
ip pim sparse-mode
interface FastEthernet0/0
ip address 20.0.1.3 255.255.255.0
ip pim sparse-mode
interface Ethernet3/1
ip address 20.0.3.3 255.255.255.0
ip pim sparse-mode
interface Ethernet3/2
description test interface
ip address 20.0.2.3 255.255.255.0
ip pim sparse-mode
ip pim rp-address 20.0.0.2
75a
ip multicast-routing distributed
interface Loopback0
ip address 20.0.0.2 255.255.255.255
ip pim sparse-mode
interface FastEthernet0/0/0
ip address 20.0.1.2 255.255.255.0
ip pim sparse-mode
ip route-cache distributed
interface FastEthernet0/1/0
ip address 20.0.6.2 255.255.255.0
ip pim sparse-mode
ip route-cache distributed
2. Auto-RP—Single RP—sparse-dense
Auto-RP utilizes the "sparse-dense" mode. This allows a Group
to be treated in Sparse Mode if an RP is known or defaults to Dense
Mode if it is not. RP information is conveyed to the routers by the
auto RP mechanism that uses 2 well-known groups 224.0.1.39 and 224.0.1.40.
The advantage of this is that any change to the RP designation will
need to be configured only on the Routers that are RPs and not upon
the leaf routers as in the static configuration. In this scenario we
still have a single point of failure and no load balancing. The range
of the RP is defined by the Time To Live (TTL) we allow the advertisements
to use. In this case I have a scope of 32. If the RP were to fail, then
all groups will revert to IP PIM Dense Mode.
Here we do not configure an RP. We configure the interface to work
in sparse and or dense mode. The routers we wish to be RP's we configure
to "send-rp-announce" and those we wish to be mapping agent
we configure to "send-rp-discovery." In this set of configurations,
75a is configured to be both the RP and the Mapping agent.
ip pim sparse-dense-mode
ip pim send-rp-announce
ip pim send-rp-discovery
Strength and Weaknesses of Auto-RP—Single RP—sparse-dense
Convergence:
Very Good
Redundancy:
Poor
Ease of use:
Excellent
Scoping:
Excellent
Safety:
Poor
Load balancing:
Poor
Configurations for Auto-RP—Single RP—sparse-dense
36a
ip multicast-routing
interface Ethernet0/1
ip address 20.0.7.6 255.255.255.0
ip pim sparse-dense-mode
interface FastEthernet2/0
ip address 20.0.6.6 255.255.255.0
ip pim sparse-dense-mode
36b
ip multicast-routing
interface Ethernet0/1
ip address 20.0.7.7 255.255.255.0
ip pim sparse-dense-mode
interface Ethernet1/0
ip address 20.0.10.7 255.255.255.0
ip pim sparse-dense-mode
interface FastEthernet2/0
ip address 20.0.8.7 255.255.255.0
ip pim sparse-dense-mode
36c
ip multicast-routing
interface Serial0/0
ip address 20.0.9.10 255.255.255.0
ip pim sparse-dense-mode
interface Ethernet0/1
ip address 20.0.10.10 255.255.255.0
ip pim sparse-dense-mode
interface FastEthernet1/0
ip address 20.0.3.10 255.255.255.0
ip pim sparse-dense-mode
36d
ip multicast-routing
interface Serial0/0
ip address 20.0.9.11 255.255.255.0
ip pim sparse-dense-mode
interface Ethernet0/1
ip address 20.0.5.11 255.255.255.0
ip pim sparse-dense-mode
72a
ip multicast-routing
interface Loopback0
ip address 20.0.0.3 255.255.255.255
ip pim sparse-dense-mode
interface FastEthernet0/0
ip address 20.0.1.3 255.255.255.0
ip pim sparse-dense-mode
interface Ethernet3/1
ip address 20.0.3.3 255.255.255.0
ip pim sparse-dense-mode
interface Ethernet3/2
description test interface
ip address 20.0.2.3 255.255.255.0
ip pim sparse-dense-mode
75a
ip multicast-routing distributed
interface Loopback0
ip address 20.0.0.2 255.255.255.255
ip pim sparse-mode
interface FastEthernet0/0/0
ip address 20.0.1.2 255.255.255.0
ip pim sparse-mode
ip route-cache distributed
interface FastEthernet0/1/0
ip address 20.0.6.2 255.255.255.0
ip pim sparse-mode
ip route-cache distributed
ip pim send-rp-announce Loopback0 scope 32
ip pim send-rp-discovery Loopback0 scope 32
3. Auto-RP—Multiple RPs—sparse-dense
This is similar to scenario 2, except we have added an additional Candidate
RP and an additional Mapping Agent (MA) in this case on 72a.
Having multiple candidates for the role of RP/MA greatly enhances the
redundancy of the PIM SM network. This redundancy reduces the risk of
groups reverting to Dense Mode and so flooding the network. We still
have only a single active RP (either per group or as in this configuration
for all groups) at any one time.
The commands for this are as per scenario 2.
ip pim sparse-dense-mode
ip pim send-rp-announce
ip pim send-rp-discovery
Strength and Weaknesses of Auto-RP—Multiple RPs—sparse-dense
Convergence:
Very Good
Redundancy:
Excellent
Ease of use:
Excellent
Scoping:
Excellent
Safety:
Very Good
Load balancing:
Poor
Configurations for Auto-RP—Multiple RPs—sparse-dense
36a
ip multicast-routing
interface Ethernet0/1
ip address 20.0.7.6 255.255.255.0
ip pim sparse-dense-mode
interface FastEthernet2/0
ip address 20.0.6.6 255.255.255.0
ip pim sparse-dense-mode
36b
ip multicast-routing
interface Ethernet0/1
ip address 20.0.7.7 255.255.255.0
ip pim sparse-dense-mode
interface Ethernet1/0
ip address 20.0.10.7 255.255.255.0
ip pim sparse-dense-mode
interface FastEthernet2/0
ip address 20.0.8.7 255.255.255.0
ip pim sparse-dense-mode
36c
ip multicast-routing
interface Serial0/0
ip address 20.0.9.10 255.255.255.0
ip pim sparse-dense-mode
interface Ethernet0/1
ip address 20.0.10.10 255.255.255.0
ip pim sparse-dense-mode
interface FastEthernet1/0
ip address 20.0.3.10 255.255.255.0
ip pim sparse-dense-mode
36d
ip multicast-routing
interface Serial0/0
ip address 20.0.9.11 255.255.255.0
ip pim sparse-dense-mode
interface Ethernet0/1
ip address 20.0.5.11 255.255.255.0
ip pim sparse-dense-mode
72a
ip multicast-routing
interface Loopback0
ip address 20.0.0.3 255.255.255.255
ip pim sparse-dense-mode
interface FastEthernet0/0
ip address 20.0.1.3 255.255.255.0
ip pim sparse-dense-mode
interface Ethernet3/1
ip address 20.0.3.3 255.255.255.0
ip pim sparse-dense-mode
interface Ethernet3/2
description test interface
ip address 20.0.2.3 255.255.255.0
ip pim sparse-dense-mode
ip pim send-rp-announce Loopback0 scope 32 group-list 10
ip pim send-rp-discovery Loopback0 scope 32
access-list 10 permit 224.0.0.0 15.255.255.255
75a
ip multicast-routing distributed
interface Loopback0
ip address 20.0.0.2 255.255.255.255
ip pim sparse-mode
interface FastEthernet0/0/0
ip address 20.0.1.2 255.255.255.0
ip pim sparse-mode
ip route-cache distributed
interface FastEthernet0/1/0
ip address 20.0.6.2 255.255.255.0
ip pim sparse-mode
ip route-cache distributed
ip pim send-rp-announce Loopback0 scope 32 group-list 10
ip pim send-rp-discovery Loopback0 scope 32
access-list 10 permit 224.0.0.0 15.255.255.255
36b#sh ip pim rp
Group: 224.128.1.1, RP: 20.0.0.3, v2, v1, uptime 00:03:01, expires 00:02:50
The RP has now changed to 20.0.0.3
36b#sh ip pim rp mappi
PIM Group-to-RP Mappings
Group(s) 224.0.0.0/4
RP 20.0.0.3 (?), v2v1
Info source: 20.0.0.2 (?), via Auto-RP
Uptime: 00:22:08, expires: 00:02:40
36b#
All groups are now using 20.0.0.3 as the RP. This is because the mapping
agents prefer the highest IP address as the RP.
4. BSR—1 RP—sparse-mode
BSR is specified in PIM version 2. BSR performs in a similar manner
to Auto-RP in that it has candidates for the RP function and routers
who relay the information concerning who is the RP for a group. BSR
does not use the Sparse-Dense paradigm. BSR sends all information hop
by hop within a PIM protocol packet to the reserved link local IPmc
group 224.0.0.13 (all PIM v2 routers). A single BSR performs very much
as a single RP does, except that it does not run the risk of reverting
to Dense Mode, and it does not offer the ability to scope within a domain.
For this configuration it is required to configure a router to send
Bootstrap messages as a candidate to do so, and to configure the routers
that wish to be an RP candidate to be RP.
ip pim bsr-candidate
ip pim rp-candidate
Please note the following DDTSs which relate to BSR functionality.
CSCdp95116
CSCdr67362
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Note The full text of the Release Notes is at the end of this paper.
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Strength and Weaknesses of BSR—1 RP—Sparse Mode
Convergence:
Very Good
Redundancy:
Poor
Ease of use:
Excellent
Scoping:
Poor
Safety:
Excellent
Load balancing:
Poor
Configurations for BSR—1 RP—Sparse Mode
36a
ip multicast-routing
interface Ethernet0/1
ip address 20.0.7.6 255.255.255.0
ip pim sparse-mode
interface FastEthernet2/0
ip address 20.0.6.6 255.255.255.0
ip pim sparse-mode
36b
ip multicast-routing
interface Ethernet0/1
ip address 20.0.7.7 255.255.255.0
ip pim sparse-mode
interface Ethernet1/0
ip address 20.0.10.7 255.255.255.0
ip pim sparse-mode
interface FastEthernet2/0
ip address 20.0.8.7 255.255.255.0
ip pim sparse-mode
36c
ip multicast-routing
interface Serial0/0
ip address 20.0.9.10 255.255.255.0
ip pim sparse-mode
interface Ethernet0/1
ip address 20.0.10.10 255.255.255.0
ip pim sparse-mode
36d
ip multicast-routing
interface Serial0/0
ip address 20.0.9.11 255.255.255.0
ip pim sparse-mode
interface Ethernet0/1
ip address 20.0.5.11 255.255.255.0
ip pim sparse-mode
72a
ip multicast-routing
interface Loopback0
ip address 20.0.0.3 255.255.255.255
ip pim sparse-mode
interface FastEthernet0/0
ip address 20.0.1.3 255.255.255.0
ip pim sparse-mode
interface Ethernet3/1
ip address 20.0.3.3 255.255.255.0
ip pim sparse-mode
interface Ethernet3/2
ip address 20.0.2.3 255.255.255.0
ip pim sparse-mode
ip pim bsr-candidate Loopback0 1
ip pim rp-candidate Loopback0
75a
ip multicast-routing distributed
interface Loopback0
ip address 20.0.0.2 255.255.255.255
ip pim sparse-dense-mode
interface FastEthernet0/0/0
ip address 20.0.1.2 255.255.255.0
ip pim sparse-mode
interface FastEthernet0/1/0
ip address 20.0.6.2 255.255.255.0
ip pim sparse-dense-mode
The command "show ip pim bsr" is useful in determining who
is the BSR and when the next update should arrive.
72a#sh ip pim bsr
PIMv2 Bootstrap information
This system is the Bootstrap Router (BSR)
BSR address: 20.0.0.3 (?)
Uptime: 00:04:23, BSR Priority: 0, Hash mask length: 1
Next bootstrap message in 00:00:37
Next Cand_RP_advertisement in 00:00:19
RP: 20.0.0.3(Loopback0)
Show ip pim rp mapping
72a#sh ip pim rp m
PIM Group-to-RP Mappings
This system is a candidate RP (v2)
This system is the Bootstrap Router (v2)
Group(s) 224.0.0.0/4
RP 20.0.0.3 (?), v2
Info source: 20.0.0.3 (?), via bootstrap
Uptime: 08:41:02, expires: 00:02:27
All groups are now using 20.0.0.3 as the RP learned via bootstrap and
the source of that bootstrap is also 20.0.0.3.
5. BSR—Multiple RPs—sparse-mode
This is similar to scenario 4, except we have added an additional BSR-candidate
and an additional RP-candidate in this case on 75a.
Having multiple candidates for the role of BSR/RP greatly enhances
the resiliency of the PIM SM network. We still have a single RP (either
per group or as in this configuration for all groups) at any one time
and still have no load balancing or scoping within a domain.
The same commands are used as per scenario 4.
ip pim bsr-candidate
ip pim rp-candidate
Strength and Weaknesses of BSR—Multiple-RPs—Sparse Mode
Convergence:
Very Good
Redundancy:
Excellent
Ease of use:
Excellent
Scoping:
Poor
Safety:
Excellent
Load balancing:
Poor
Configurations for BSR—Multiple-RPs—Sparse Mode
36a
ip multicast-routing
interface Ethernet0/1
ip address 20.0.7.6 255.255.255.0
ip pim sparse-mode
interface FastEthernet2/0
ip address 20.0.6.6 255.255.255.0
ip pim sparse-mode
36b
ip multicast-routing
interface Ethernet0/1
ip address 20.0.7.7 255.255.255.0
ip pim sparse-mode
interface Ethernet1/0
ip address 20.0.10.7 255.255.255.0
ip pim sparse-mode
interface FastEthernet2/0
ip address 20.0.8.7 255.255.255.0
ip pim sparse-mode
36c
ip multicast-routing
interface Serial0/0
ip address 20.0.9.10 255.255.255.0
ip pim sparse-mode
interface Ethernet0/1
ip address 20.0.10.10 255.255.255.0
ip pim sparse-mode
36d
ip multicast-routing
interface Serial0/0
ip address 20.0.9.11 255.255.255.0
ip pim sparse-mode
interface Ethernet0/1
ip address 20.0.5.11 255.255.255.0
ip pim sparse-mode
72a
ip multicast-routing
interface Loopback0
ip address 20.0.0.3 255.255.255.255
ip pim sparse-mode
interface FastEthernet0/0
ip address 20.0.1.3 255.255.255.0
ip pim sparse-mode
interface Ethernet3/1
ip address 20.0.3.3 255.255.255.0
ip pim sparse-mode
interface Ethernet3/2
ip address 20.0.2.3 255.255.255.0
ip pim sparse-mode
ip pim bsr-candidate Loopback0 1
ip pim rp-candidate Loopback0
75a
ip multicast-routing distributed
interface Loopback0
ip address 20.0.0.2 255.255.255.255
ip pim sparse-dense-mode
interface FastEthernet0/0/0
ip address 20.0.1.2 255.255.255.0
ip pim sparse-mode
interface FastEthernet0/1/0
ip address 20.0.6.2 255.255.255.0
ip pim sparse-dense-mode
ip pim bsr-candidate Loopback0 1
ip pim rp-candidate Loopback0
Here we see that there are 2 candidates to be BSR 20.0.0.2 and 20.0.0.3.
This concurs with the configuration information above. 20.0.0.3 is the
BSR, because it has the higher IP address.
75a#sh ip pim bsr
PIMv2 Bootstrap information
BSR address: 20.0.0.3 (?)
Uptime: 00:23:32, BSR Priority: 0, Hash mask length: 1
Expires: 00:01:57
This system is a candidate BSR
Candidate BSR address: 20.0.0.2, priority: 0, hash mask length: 1
Next Cand_RP_advertisement in 00:00:18
RP: 20.0.0.2(Loopback0)
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