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An Overview

GROS ( G ROS IS A R OUTING O PERATING S YSTEM ) Phase II Batch : 6 Guide :Sabitha . S Hemant Pillai Dean John Abraham Krishnakumar.R. An Overview. Review of previous stage. Fast Ethernet card reception and transmission. Transfer of packets from one network to another.

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An Overview

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  1. GROS(GROS ISA ROUTING OPERATING SYSTEM)Phase II Batch : 6Guide :Sabitha . SHemant PillaiDean John AbrahamKrishnakumar.R

  2. An Overview • Review of previous stage. • Fast Ethernet card reception and transmission. • Transfer of packets from one network to another. • Equalizing the priority of cards. • Bug yet to be solved

  3. Review of previous stage • Booting. • Protected mode switching. • Reception and transmission of packets using PCI and ISA cards.

  4. Preliminaries • Speed of network cards Ordinary – 10Mbps Fast - 100Mbps Gigabit Ethernets – 1000Mbps • We use Fast Ethernet cards , 100Mbps • Hubs are of 10Mbps • So Uses Auto-negotiation

  5. Auto-Negotiation • Checks the ability of the partner. • Selects the common, maximum possible speed. • Done by the transceiver on the card. • In our case it is REALTEK’s 8139 chipset .

  6. Fast Ethernet cards • GROS function pci_bios gets us the base address of the card. • Situation demands two cards • Had to search Bus no 0 and 1 to find the address of both n/w cards • Hardware address can be got as in case of Ordinary cards (Read from PROM). • Done when initializing the card. • Transmission different

  7. Environment • Two networks • Can be heterogeneous networks with different OS’es running over IP. • A single machine with GROS, connected to two networks • The machine has two Fast Ethernet cards.

  8. The Plan network2 network1 check Case 1 : Packet from networ1 to network2 Case 2 : Packet from network 2 to network 1 System with GROS

  9. The Network card class ne • ne , Object used for network card management. • Presently it has only one method, init. • Declared In file ne.h. • Next slides, code is being explained . . . . represents few lines of code

  10. The code for ne class ne { public: unsigned int *rx_ring; void init(int notFirInit, int ioAd); }

  11. Highlights of ne • rx_ring - is the reception ring. • void ne::init(int notFirInit, int ioAd){ .......... if (!notFirInit) { /* Get hw address*/ /* Print it */ . . . . . . . }

  12. /* Bring chip to low power mode */ outb(0xC0, ioAd + CFG9346); outb(0x03, ioAd + CONFIG1); outb('H‘, ioAd + HLTCLK); /* Reset the chip */ outb(CMDRESET, ioAd + CHIPCMD); for (i = 1000 ; i > 0 ; i-- ) if ((inb(ioAd + CHIPCMD) & CMDRESET) == 0) break; . . . Fixup up the Max DMA . . . . . . Burst and duplex mode . . . outl((unsigned long)rx_ring, ioAd + RXBUF);

  13. . . Put the card to promiscous mode . . . . Enable the transmission . . . . . Enable interrupts . . . } • Using this class we declare : ne *n=(ne *) 0x5000; • Receive ring is initialized in the fn. ‘newmain’ as n->rx_ring=(unsigned int*)0x8000 • n->init(0, ioAd1) • n->init(0, ioAd2) (ioAd1 and ioAd2 got by function pci_bios )

  14. Interrupts • enable_irq()function enables the irq’s of keyboard and the two n/w cards. • Two function are registered : net1() as ISR of n/w card 1 net2()as ISR of n/w card 2 • Both functions call common function : net(addr1,addr2) net1 calls with ioAd1 and ioAd2 net2 with ioAd2 and ioAd1 as parameters

  15. Reception • Both the card receives to n->rx_ring one at a time. • After a single reception : 1 1 2 n->rx_ring rest of pckt status size next Size = header + pckt length

  16. High lights of Transmission • Put the address of packet to be transmitted to Transmit address register outl((unsigned int)(n->rx_ring+4), ,ioAd2+TXADDR0); • Tell the network card to transmit it outl(0xffffdfff & (myflag| ((unsigned int)hdr.h.count-4)) ,ioAd2+TXSTATUS0);

  17. The difference • Usual drivers use upto 4 xmit buffers • When transmit success, interrupt raised • Buffer marked as free • Here only one buffer used. • Wait until a single packet is transmitted while(!(inl(ioAd2+TXSTATUS0)&0x00008000)) { times++; if (times == 100) break; }

  18. The Bug • Traffic of one side greater then always the card of that side gets serviced(if it has low irq no.) • The trouble is with 8259 Interrupt controller • After an interrupt is serviced, its priority is made lowest . Hence all equal /* The code below equilizes the */ /* priority of all IRQ's D7=R=1 */ /* and D5=S=1 */ outb(0xa0,0x20); outb(0xa0,0xa0);

  19. Checking • Transmitted packets from machine in one n/w to a machine in other n/w • In the other n/w we checked using TCPDUMP • PING, TELNET and other tools does work • Tried changing the ip address when the packet was within GROS. Succeded

  20. Bug yet to be solved • GROS crashes when no of packets reach 2400 range • First Observed when : - LINUX NFS client m/c on one n/w - Server on another n/w - Ran X windows - Desktop was being transmitted crashed. • Verified packet nos by using the broadcast option of PING and TCPDUMP. • Changed stack location without success.

  21. Summary • Fast Ethernet card Functionality • Getting packet from one n/w to another • IRQ priority problem • Checking • The remaining Bug

  22. Thank You

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