IP over networks
Heikki Almay
Kari Melkko
Risto Mononen
IP seminar 28.9.1998
ipbb.PPT / 28.9.1998 / Risto Mononen page: 1
IP in the backbone
•
“IP over anything” rule guarantees the
connectivity
•
Link-layer specific encapsulation and
possibly connection setup needed
•
•
Common link-layers: LAPF, AAL5, PPP
•
Routers have several IP interfaces with
possibly different physical media
PDH, SDH or WDM transmission path in the
bottom
ipbb.PPT / 28.9.1998 / Risto Mononen page: 2
Eg. Cisco 12000 Series
•
•
Quotes from http://www.cisco.com/warp/public/733/12000/gsrfs_ds.htm:
•
Supports a combination of IP over SONET/SDH and ATM interfaces, including other
high-speed media:
The Gigabit Switch Router (GSR) delivers scalable IP forwarding and services
performance in a carrier-class platform, enabling high-speed IP backbones to scale
to OC-3 (155 Mbps), OC-12 (622 Mbps), and OC-48 (2.4 Gbps) facilities.
•
•
•
•
Four-port OC-3/STM-1 IP over SONET/SDH
One-port OC-12/STM-4 IP over SONET/SDH
One-port OC-12/STM-4 ATM
Future line cards, including:
•
•
•
•
Four-port OC-3/STM-1 ATM
Four-port OC-12/STM-4 IP over SONET/SDH
One-port OC-48/STM-16 IP over SONET/SDH
Gigabit Ethernet
ipbb.PPT / 28.9.1998 / Risto Mononen page: 3
Frame Relay
•
•
•
Variable size frames over PCM links
LAPF / HDLC framing
"Streamlined X.25 / LAPB":
•
•
•
•
outband signalling
layer 2 multiplexing
end-to-end flow and error control above LAPF
hop-by-hop FCS checking to drop corrupted frames
Application
Application
TCP/IP
TCP/IP
LAPF - - - - - - - - - - LAPF - - - - - - - - - - - - LAPF
PHY
PHY
PHY
End node
Switching node
End node
ipbb.PPT / 28.9.1998 / Risto Mononen page: 4
Multiprotocol over FR
•
Routing mode
•
•
need layer 3 NLPID
IP NLPID is 0xCC
save 48 bits over bridging
•
Bridging mode
•
•
•
•
encapsulate whole MAC frame
NLPID 0x80 + SNAP define (LAN)
protocol
FR level fragmenting
Complicated ARP
•
•
Usually DLCI has only local significance
Frame Relay network provides a
method for obtaining the correct DLCIs
ipbb.PPT / 28.9.1998 / Risto Mononen page: 5
•
Encapsulated IP packet:
•
•
•
•
•
•
•
flag 0x7E
Q.922 address (DLCI)
Control 0x03
NLPID 0xCC
IP Datagram
FCS
flag 0x7E
IP over ATM
•
“IP over ATM: A Framework Document" [RFC1932]
•
LLC/SNAP encapsulation is default
CLIP and LANE
•
TULIP strips IP header
need end-to-end ATM
•
TUNIC strips layer 4 header
replace TCP port based multiplexing with VC multiplexing
•
"Multiprotocol Encapsulation over ATM Adaptation Layer 5" [RFC1483]
•
•
•
MPLS work lead to new draft 1998
Working technology in single LIS (IP subnet)
Routing between LISes ongoing work
ipbb.PPT / 28.9.1998 / Risto Mononen page: 6
IP over SONET/SDH and WDM
•
•
ANSI and ITU-T flavors of synchronous links
"PPP over SONET/SDH" [RFC1619]
•
•
•
•
octet synchronous HDLC encapsulation
add scrambling 1998
scales up to OC-48/STM-16/2.5 Gb/s
WDM will provide huge bandwidth > OC-48
•
Lucent's Simplified Data Link (SDL) delineation proposal
variable length frames
header CRC
payload CRC
hunt for SONET H4 byte (?) and/or correct header CRC
add QoS and multiplexing to get “ATM lite”
ipbb.PPT / 28.9.1998 / Risto Mononen page: 7
IP switching
•
Industry suggestions
•
data driven
Ipsilon Flow Management Protocol (IFMP), Cell Switch Router (CSR)
snoop packets to find a flow
•
control (topology) driven
Tag Switching, Aggregate Route-Based IP Switching (ARIS), IP Navigator
routing updates and RSVP messages trigger VC setup
•
•
•
•
ATM Forum: MPOA/NHRP
IETF: RSVP, MPLS
Traditional Internet: connectionless datagram forwarding
(IP) Switching is always connection oriented and needs signalling: RSVP, LDP, SS7,
PNNI, …
•
Internet wants all the switching goodies with new names
ipbb.PPT / 28.9.1998 / Risto Mononen page: 8
DiffServ
•
•
•
•
•
•
•
Last pure stateless attempt?
Take IP header TOS bits in use
Priority queuing enhances QoS
Still best-effort inside each “class”
CAC or pricing to protect backbone?
Interoperate with RSVP in enterprise net and ATM in backbone
Van Jakobson's research http://www-nrg.ee.lbl.gov/
•
Research projects with their own web pages include:
CBQ (Class-Based Queueing, including link-sharing);
ECN (Explicit Congestion Notification);
RED gateways (Random Early Detection Gateways);
SRM (Scalable Reliable Multicast);
the VINT project, based on the UCB/LBNL Network Simulator ns ( ns-1, ns-2)
Adaptive Web Caching ;
ipbb.PPT / 28.9.1998 / Risto Mononen page: 9