Development of the FITELnet-G20 Metro Edge Routerby Tomoyuki Fukunaga *With the increasing use of broadband Internet, it is to be expected that fiber-tothe-home (FTTH) service will expand as the means of providing access. And ascommunications carriers are moving toward IP-based data networks that include voice telephony,requirements for higher performance, greater functionality and higher reliability will be placed on
metro edge routers. To respond to these requirements we have developed the FITELnet-G20
metro edge router, which realizes high functionality in the form of QoS, multicasting and virtualprivate networks (VPNs) based on multi-protocol label switching (MPLS), of which carriers are in
great need, by means of full-wire-rate relaying without degradation of performance.

ABSTRACT1.

INTRODUCTION

With the higher speeds of broadband access lines,
the expansion of Internet architecture using the VPN
services provided by communications carriers and theestablishment of regional information networks, the trafficon IP networks is expanding year by year. Moreover
carriers and service providers are also moving toward
voice-over IP (VoIP), real-time content distribution, andmultifunctional services such as IP-VPN and L2-VPN
using MPLS.
This presents the metro edge routers, whichconnect user access networks and core networks, withrequirements for higher performance in relaying data
without stress and higher functionality with respect tovarious services, together with higher service reliability.
At the end of 2001 the FITELnet-G12 was introduced
to target Ethernets, which are coming into wider use ina number of markets that exceed the scope of LANs

Photo 1*

Appearance of FITELnet-G20 metro edge router.

FITEL Network Lab.

--backbones, metropolitan area networks (MANs) andwide area networks (WANs). In this paper we reporton the development of the FITELnet-G20 metro edge
router (Photo 1), which represents an extension of thetechnology of the FITELnet-G12, offering significant
improvements in scalability, functionality and performance,plus the performance and high-grade functions onlyachievable with a backbone core router.

2.

FUNCTIONSIn order to allow carriers to operate network services inan economical yet effective manner, and to realize highquality IP communications in an enterprise environmentthat uses high-grade applications, the FITELnet-G20
metro edge router is provided with the functions describedbelow.
2.1 Large-Volume Routing Information
The FITELnet-G20 makes possible the handling of
sufficient routing information (VRF) and label information
to cope with Internet full routes and the IP-VPNs ofcommunications carriers. Table 1 shows the specifications
for the route information, etc. for the FITELnet-G20. The
FITELnet-G20 is capable of full-wire-rate relaying while
searching these large databases.
2.2 VLAN Multiplexing
The FITELnet-G20 supports 2000 802.1q-tag-VLANs
and 26 port-VLANs with respect to tag-VLAN and 26 port
VLANs on giga-Ethernet and fast Ethernet. For each
VLAN it is possible to set whether either IPv4 or IPv6
operates or not. And by using the VLAN aggregation
function for IPv4 or by setting individual subnets for IPv6,Furukawa Review, No. 24

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Development of the FITELnet-G20 Metro Edge Router

Table 1

Specifications of FITELnet-G20 metro edge router.

No. of VLANs

100 per FE, 1000 per GE (Total: 2026)

IPv4 logic IFs

2,000

L2 MAC learning tables

300,000

IPv4 routing information items

300,000

IPv6 routing information items

200,000

ARP entries

50,000IP-VPN Max. VRF

2,000

MPLS label paths

20,000MPLS pairs

128

Access list entries

1000 per FE, 10,000 per GE (Total: 20,000)

L2 area network

IP core network
L2 relayBAS

L3 relayBAS

FITELnet-G20

OLT/line aggregating device

FITELnet-G20

Figure 2

Tag-VLANL2 switch

10.0.0.1

10.0.0.2

10.0.0.3

10.0.0.4

Same subnet allocation

Figure 1

Network segmentation on same subnet using
VLAN aggregation.

it is possible to separate address maps into VLAN units 1).
In the address separation environment, the security ofeach separated segment is assured by parallel use of theARP filter function. In this way it is possible to realize, inan IP network system, a user accommodation that is bothsecure and scalable. See Figure 1.
The FITELnet-G20 also makes possible the free settingof broadcast domains. It is possible, for example, toaggregate different 802.1q VLAN tag-terminal interfaces
in the same broadcast domain. Similarly in relaying,
when, for example when a tag 100 interface and tag 200
interface are set to the same broadcast domain, layer 2
relaying is possible between terminals beyond both of theinterfaces. In this case transmission is accomplished bychanging the tag in accordance with the interface.
The FITELnet-G20 also makes it possible to set
broadcast domains for each protocol. This enables layer 3
relaying for L3 frames such as ARP, or IPv4 and IPv6, andlayer 2 relaying for others within the broadcast domain(Figure 2).
2.3 QoS/CoS Functions
When multiple users are aggregated by VLAN
multiplexing on a single Ethernet, it may happen thatthe maximum traffic of one of the users occupies

Protocol bridging function.

virtually all of the Ethernet bandwidth, interfering withthe communications of the other users. To avoid such asituation, QoS is needed to guarantee bandwidth to eachuser.
The FITELnet-G20 offers the following full range ofQoS/CoS functions:1) Supports PPQ developed by RIC as well as DiffServ;
2) Offers a fairness function for each VLAN. During
VLAN fairness operation, maximum rate control per
VLAN and bandwidth control with respect to VLAN
groups are enabled. In addition, other traffic such asVoIP can be handled by configuring priorities within
the VLAN.
3) Detailed policing is made possible by means ofaccess lists.
4) Policing of both input and output interfaces issupported for each VLAN. Shaping at output
interfaces is also supported. This makes possible
detailed bandwidth control to the user side.
The FITELnet-G20 thus realizes the above QoS
functions in a wire rate communications environment.
The architecture for the rapid realization of complex QoS
functions is as shown in Figure 3.
2.4 Multicasting
The use of multicasting makes it possible to realize largescale real-time content distribution or delivery, somethingthat was impossible on conventional, mainly unicast,contents delivery networks (CDNs). In addition theFITELnet-G20, by collaboration with a RADIUS server at
the service provider edge, has the function of relaying only
data addressed to authenticated users. In this way a CDN
can be so configured as to realize general-purpose user
authentication and accounting management, irrespectiveof the delivery server or user environment (Figure 4).
And with QoS corresponding to multicasting, video
traffic by multicasting are guaranteed even in situations
where various traffic is mixed, thereby enabling service
differentiation.

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Development of the FITELnet-G20 Metro Edge Router

Table 2

Switch fabricIngress
network processor

Egressnetwork processor

Output queue, priority
decision on dumping

MPLS functions of FITELnet-G20.

RFC2457bis
IP-VPN

No. of VRFs

Classification

Tag-VLAN collaboration
LDP

Policing
Signaling

Marking

2000

LDP expansion (port 711 compatible)

Marking

RSVP-TE

Policing

StaticOutput queue, priority
decision on dumping

Classification

Traffic engineering

OSPF-TE
IS-IS-TE

QoS/CoS

Output queue
Input port

L2-VPN (TLS)

Output port
End user

Figure 3

Contentdeliveryserver

Service provider network(4) Multicast stream

FITELnet
G20

Other carrier’s Label path
IP-VPN

L2-VPNFITELnet
G20

FITELnet-G20

L2-VPN(3) Route inquiry

Typical configuration for MPLS-VPN service network.

(2) IGMP membership report(2) IGMP membership report

Figure 4

Label path Other carrier’s
IP-VPNRADIUS
serverFigure 5

User’s PC

MPLS network
FITELnet
G20

FITELnet-G20

Provider edge
FITELnet-G20

Customer edge

End user

Forwarding flow.

(1) Delivery request

Typical configuration for content delivery system.

2.5 Multi-Protocol Label Switching (MPLS)Since the time of the FITELnet-G12, forerunner to theFITELnet-G20, we have participated in various MPLS
forums and interconnectivity tests, establishing a proventrack record in interconnectivity. With the FITELnet-G20
this activity has continued, providing a wide range ofMPLS functions (see Table 2).
2.5.1 VPNMPLS has received attention as the backbone protocol
for virtual private network services provided bycommunications carriers.
The FITELnet-G20 establishes a label switched path(LSP) for a maximum of 50,000 pairs, enabling theconfiguring of IP-VPNs using the RFC2547bis standard,and L2-VPNs that provide label switching by looking at theMAC Destination Address of the Ethernet frame. It also
supports connection to wide-area Ethernet services likemetropolitan area networks (MANs) and L2-VPNs.

2.5.2 MPLS-IX
MPLS-IX, which uses MPLS with IX, a technology forinterconnection between ISPs, has received attention.
Since it is not restricted with respect to data link media, it
allows use of wide-area link media such as POS, and isrecognized for enabling wide area dispersal of IX. R&Dand technology verification are being carried out primarily
by distix (next-generation IX research group) 2).
FITELnet-G20 supports the functions required toconfigure MPLS-IX, including C’sC, LDP on RSVP, andLDP on LDP, accommodating to various types of MPLS-IX(Figure 5).
2.5.3 MPLS QoS
The label path of ordinary MPLS is determined by the IP
Destination Address. Thus data destined for the same
IP network will pass over the same label path. For thisreason, even when a path through which data for a certain
IP network passes changes to a congestion state due toother traffic, the data must pass that path. To overcome
this problem the FITELnet-G20 is provided with an MPLSQoS function. When MPLS QoS is used the label path iscontrolled not only by the IP Destination Address, but by
a flow that can be designated by a transmitter address orother access list, thereby in effect enabling traffic control
to be carried out for the network as a whole (Figure 6).

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PC1
DHCPserver

FITELnet-G20

PC2

IP (v4/v6) core network

RADIUSserverPC1 label path
PC2 label path

RADIUSFITELnet-G20

MPLS network
FITELnet-G20

802.1x(EAP)

OLT/line aggregating device

ServerFigure 6

Typical configuration for MPLS-QoS.

Figure 8

2.6 IPv6
An IPv4/v6 dual stack is provided, thereby supportinga v4 tunnel and v6 tunnel as solutions for transferringfrom v4 to v6. It also makes it possible for v6 users to beconnected over a v4 network (v6 over v4), and conversely
for v4 users to be connected over a v6 network (v4 overv6). See Figure 7.
2.7 Access Authentication
The FITELnet-G20 performs user authentication using
IEEE802.1x and RADIUS and distributes addresses forauthenticated users only, thereby realizing secure plug &play at the edge router 3).
Specifically it expands the concept of 802.1x port
authentication at the edge router, performing all
authentications with respect to port, VLAN and MAC
address.
Automatic address setting for hosts that have been

IPv4 terminal

IPv4 hdr

data

IPv6 terminal

IPv6 hdr

authenticated is carried out for IPv4 by DHCP and for IPv6
by router advertisement. These mechanisms provide aplug & play function of assured security (Figure 8).

3.

PERFORMANCEIn relaying equipment functionality and performance arein a trade-off relationship, in which greater sophisticationof function brings a comparable drop in performance.
For example if the number of items of routing information
held is increased the number of routing searches withrespect to a certain address also increases, so that thesearch requires a longer time and relaying performancedecreases. Similarly if set to detailed policing, the numberof judgment criteria with respect to transferred data
increases, and performance again tends to decrease.
Enhancing hardware resources to increase speed

IPv6 hdr IPv4 hdr

IPv4network

Typical configuration for authentication
on network access.

data

IPv4 hdr

dataIPv6
network

dataIPv4 hdr IPv6 hdr

IPv6networkIPv4
networkdata

IPv6 hdr

IPv4
network

Figure 7

IPv4 terminal

data

IPv6 terminal

IPv6
networkv4 over V6 and v6 over v4.

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Large RAMTSE (NP)

Large RAM

Hybrid IC

TSE (NP)

High-speed CAM

Figure 9Hybrid method using CAM and tree search engine.

will obviously cost higher. The FITELnet-G20 uses a
programmable high-performance network processor andincorporates other techniques for increasing performance,
so that it can provide higher functionality, higherperformance and lower cost.
3.1

High-Speed Searching with a Hybrid (CAM+TSE)
MethodSince the FITELnet-G20 handles 300,000 entries ofrouting information, higher speed searching of this hugevolume of data for the required information is the key tohigher performance. Hardware-based search techniques
may be broadly divided into two types:
1) Content addressable memory (CAM), and2) Tree search engines (TSE).
CAM methods are capable of extremely fast searches,but cost increases in proportion to the number of data
items searched. TSE methods, on the other hand, use
inexpensive memory and therefore realize cost savings,
but the search time tends to increase rapidly with thenumber of search targets. The FITELnet-G20 adopts ahybrid system that combines the advantages of these twomethods (Figure 9).
The FITELnet-G20 achieves even higher efficiency bysharing the high-cost CAM among a number of network
processors. It incorporates logic for effecting this sharing
and, by developing custom logic that clears the CAM
access bandwidth bottleneck due to sharing, and achieves
asynchronous CAM access from multiple threads of thehigh-speed network processors, thereby realizing CAM
sharing.

3.2 Collaboration with QoS Functions
Another important work of the network processor's
search function is to support QoS functions. As in routing
searches, a variety of searches (access list searches)
occur with respect to QoS. Each time a frame isrelayed, the network processor searches the access list
corresponding to that frame and if it gets a match, carries
out QoS processing in accordance with the policing set up
in the access list.
In access list searches, the FITELnet-G20 uses aportion of the CAM search from the hybrid search referred
to above, making it possible to perform complex accesslist searches at high speed. This high-speed searchcapability makes possible the complex MPLS QoS
function with no degradation of performance.

4.

CONCLUSION

In this paper we have reported on the functions of theFITELnet-G20 metro edge router, and on the techniques
used to realize them. Making use of programmablenetwork processors and accumulated network solution
technologies, we believe we have developed a metroedge router that can meet the needs of customers. We
believe that in the future new requirements will be placedon metro edge routers with respect to functionality andperformance, as well as scalability, and we intend torespond with flexibility.

REFERENCES
1) D. McPherson and B. Dykes, “VLAN Aggregation for
Efficient IP Address Allocation,” Feb.2001, RFC3069
2) Nagami, Nakagawa et al., Design of Distributed IX
Architecture Using MPLS (in Japanese)
3) IEEE Std 802.1x-2001 Port-Based Network Access ControlFurukawa Review, No. 24200353