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Contents Simply…
– Who we are – Where we were – Where we are – Where we’re going
…in the hope it’s mutually beneficial.
STFC - One of seven publicly funded Research
Councils with broad overall remit of supporting UK scientific research
- Activities range from involvement in the Large Hadron Collider to running super computers
- 1700 staff + 100s more in partner orgs - Mix of staff, partner organisations and
tenants - 4,500 telephone extensions - “Big data”… Janet @ 40 Gbps - This is the Harwell Oxford Campus
The Dark Ages • Ericsson MD110 adopted late 1990s • Digital Time Division Multiplexing PABX:
– digital, – traditional analogue and – ISDN extensions
• Distributed cabinets containing various slot-in “line cards” (e.g. a card supporting 16 digital extensions).
• Cabinets connected to 1-2 Group Switches acting as “brains” of system.
fibres
......and so on from 1 to 11……
Fibre Line
Driver
Group Switch
0
Fibre Line
Driver
Group Switch
1
Cabinet 1
Analogue (e.g. fax)
ISDN (e.g. VC) Digital
Fibre Line
Driver
Cabinet 11
Analogue (e.g. fax)
ISDN (e.g. VC) Digital
Fibre Line
Driver
PSTN/ISDN Trunks… BT, Voda
etc.
PSTN/ISDN Trunks
Harwell Site: Previously
The Enlightenment • Ericsson -> Aastra -> Mitel developed MX-ONE platform: IP telephony
(SIP) software PBX running under Linux on commodity servers.
• MX-ONE provides time limited backwards compatibility for old cabinets • Cabinets still talk TDM to telephone extensions • Cabinets are IP enabled and talk SIP to the servers which manage
them. • Legacy line cards can be accommodated in a new style chassis, but
– expensive… – benefits of IP telephony and Unified Communications not realised
• So majority of users will migrate to SIP clients (physical handsets or softphones) which register to one of the servers.
• Legacy line cards will only be retained where essential, e.g. analogue lift phones, PSTN/ISDN trunk lines
• STFC used MX-ONE as it gives a vital stepping stone between TDM and full SIP
Primary Tele IP Router
Server managing Cabinet
1
Standby Tele IP Router
Cabinet 1
Digi, analogue or ISDN
Ethernet Switch
IP
TDM Server
managing SIP clients PoE
Switch
SIP Handsets
IP
IP
Voice LAN
PSTN/ISDN Trunks… BT, Voda
etc. Data LAN
Firewalls & Border Routers
Two of several servers
Voice VPNs to other
STFC sites
Potential SIP trunks
Janet
Harwell Site: Now
So in Future • 11 old cabinets retired • Legacy line cards housed in 2-3
smaller, modern chassis, for: – analogue lift phones, faxes etc. – PSTN/ISDN trunk lines (if retained)
• Majority of users move to SIP clients
• So, do most things in software with the flexibility that brings.
Network Resilience Primary
Telephony IP Router
Standby Telephony IP Router
Ethernet Switch
PoE Switch
PoE Switch
Cabinet 1
OR VRRP heartbea
t
MLAG: Multi-chassis Link AGgregation
ESRP Extreme Standby Router Protocol (proprietary)
Combines L2 and L3 redundancy
Switch sees
standard LAG
VRRP Virtual Router Redundancy Protocol Two routers share gateway IP and MAC
address
Inter Switch Communicatio
n
Healthcheck +
User traffic blocked to avoid loops
Drivers – Why? 1. Obsolescence of MD110 Cabinets in 2016-17
2. Create a single cross-site system for easier system and workload management (promote cross-site working)
3. Migrate to standards based (SIP) system for better interoperability and potential cost savings (e.g. “cheap” softphones)
4. Reduce costs: – Route inter-site calls over Janet for free – Potentially replace existing PSTN/ISDN trunks with SIP equivalents – Remote and mobile workers (particularly abroad) can use SIP clients on laptops or
smartphones registered to a STFC SIP gateway over Wi-Fi – Similarly, on-site GSM costs can be reduced by using smartphone SIP clients – BYOD: support use of personal mobiles for company business, reducing number of STFC
issued mobiles – smartphone battery life still an issue
5. Free up network engineer effort: login/off SIP handsets = less work for office moves
6. Explore Unified Comms, e.g. “presence” features
How? (1) 1. Separation 2. Resilience 3. Simplicity
• New “voice” network largely physically separate to existing “data” network – Consolidation (cost & time savings) vs. resilience – Recent data network outage highlighted benefit of separation
• Deployment scenarios: buildings assessed on case by case basis – Ideally separate data and PoE voice switches, but… – Rack space, power and backhaul copper/fibre can be limited, so… – Shared switches used where necessary
• In most cases, PCs will not be piggybacked on SIP handset’s network connection – Separation of voice and data – Upfront port cost vs. long term management cost (changing PC VLANs for office moves)
• Separate physical uplinks to firewalls and border routers with separate inter-site
voice and data VPNs
How? (2) • Network resilience wherever possible:
– master and standby voice network routers – resilient cable/fibre routes – failover ISC DHCP for assigning handsets IP addresses – primary/secondary Apache servers for deploying handset configuration files – UPSs for servers and network kit, but not edge switches or handsets
• No QoS… yet – Is it really needed on a voice only network? I guess we’ll find out :-) – Enabling it on our 40 and 80 Gbps core may have unintended consequences on our science
data – Understandably QoS unsupported over Janet
• ≤ 200 handsets per VLAN: small Layer 2 broadcast domain
• No server virtualisation… yet
Next • Apart from the small matter of upgrading 4500 extensions to SIP… • To achieve cost savings on handsets we need a cheap SIP software client to replace
them with…
• And to allow softphones to be used outside STFC without a VPN connection we need
a SIP gateway. • Recommendations?
Conclusion • Upgrade driven by:
– Existing equipment going EoL – Cost savings – Produce single, simpler system for technical and management
efficiencies – Explore end user benefits: Unified Comms
• Approach focused on: – Separation from existing data traffic – Resilience – Simplicity
• Much more to do
