Date post: | 21-Dec-2014 |
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Technology |
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CONFIDENTIAL
Multihoming using Juniper MX80
Howard Hart
A short pause for a commercial
Rated #1
$ Free Phone
Service
Break through
Voice Quality
Unique New
Voice Services
....
Platform for Future
Managed Services
Ooma Business
• Hosted VoIP services used by hundreds of
thousands of customers
• Carrying over a hundred million minutes of
call traffic per month
• Pushing millions of packets per second
• Standards based VoIP using Session
Initiation Protocol (SIP) signaling and Real
Time Protocol (RTP) media
Ooma Challenges
• RTP is unforgiving and so are customers
– One dropped packet and user hears a pop
• Can buffer out-of-order RTP packets up to
100 msecs.
– Just five 20 msec packets for most codecs
• More than one network switch
hasn’t been up to the challenge
at our scale
UNCLE
?
Why Juniper?
• We’ve got enough challenges--don’t need to add router limitations to the mix
• MX80 provides wirespeed packet-switching with zero buffering
– Average 40 msecs coast to coast
– Plus buffer bloat delays
– Plus local head-of-line blocking on NAT
• 50 million pps capacity on MX80 gives us lots of headroom
Why multihome?
• Carriers go down
• Hardware fails
• Maybe some of your destinations are
cheaper through an alternate carrier
• Your resume’s a little light and you’re not
up to speed yet on Web 2.1
Topology
• Control inbound flow via BGP
announcements and AS prepending
• Control outbound flow via VRRP
• Automate failover using Juniper interface
tracking feature
Network Diagram
172.16.1.0/30 2
1
2
Interwebs
ASN 1000
192.168.1.0/24
ASN 12345
10.1.1.0/30 2
1
xe-0/0/0
xe-0/0/1 xe-0/0/2
Joesgarage
ASN 2000
172.16.1.4/30 6
5
3
Interwebs
10.1.1.4/30 6
5
xe-0/0/0
xe-0/0/1 xe-0/0/2
Joesgarage
Router 1 Router 2
VRRP Configuration
Router1:
set interfaces xe-0/0/0 unit 0 family inet address 192.168.1.2/24 vrrp-group 0
edit interfaces xe-0/0/0 unit 0 family inet address 192.168.1.2/24 vrrp-group 0
set virtual-address 192.168.1.1;
set priority 100;
set track interface xe-0/0/1 priority-cost 10;
set track interface xe-0/0/2 priority-cost 5;
Router2:
set interfaces xe-0/0/0 unit 0 family inet address 192.168.1.3/24 vrrp-group 0
edit interfaces xe-0/0/0 unit 0 address 192.168.1.3/24 vrrp-group 0
set virtual-address 192.168.1.1;
set priority 120;
set track interface xe-0/0/1 priority-cost 25;
set track interface xe-0/0/2 priority-cost 10;
VRRP Configuration (cont)
• VRRP failover in 2 seconds or less – though configurable with advertise-interval setting
• VRRP tracks local interfaces--can’t be easily tied to BGP state
• Subtract priority-cost from priority when link goes down – Router2 xe-0/0/1 is the preferred outbound interface
at priority 120
– If Router2 xe-0/0/1 goes down, Router1 xe-0/0/1 takes over
• 120 – 25 = 95 < Router1 xe-0/0/1 priority 100
BGP Configuration
Router 1 [edit protocols bgp]
set local-as 12345;
set group interwebs type external;
set group interwebs export bgpnets;
set group interwebs neighbor 172.16.1.2 peer-as 1000;
set group joesgarage type external;
set group joesgarage import lowerpref;
set group joesgarage export [ prepend5X bgpnets ];
set group joesgarage neighbor 10.1.1.2 peer-as 2000;
[edit policy-options]
set policy-statement bgpnets term to-allow from protocol [ direct static ];
set policy-statement bgpnets term to-allow from route-filter 192.168.1.0/24 exact;
set policy-statement bgpnets term to-allow then accept;
set policy-statement lowerpref then local-preference 90;
set policy-statement prepend5X then as-path-prepend “12345 12345 12345 12345 12345”;
BGP Configuration (cont)
• Router with fewest prepends wins for inbound traffic
• Use local preference (default 100) to steer traffic out preferred outbound provider
• BGP failover after (typical) 30 second reconvergence
• Prepending doesn’t protect from flapping – Web users just hit reload. VoIP customers hit speed
dial to customer support
• Throw in BGP community usage to fine tune specific carriers through specific interfaces
Useful Commands
• Show vrrp Interface State Group VR state VR Mode Timer Type Address
xe-0/0/0.0 up 0 master Active D 3.453 lcl 192.168.1.2
• Show bgp summary
• Show route protocol bgp <network>
• Show bgp group
• Show nearest open bar