Series 500 Frame Relay/Leased Line Bridge/Router Reference Manual LR1530A-R3, LR1530A-EU-R3, LR1531A-R2, LR1535A-R2 5500100-10 equivalent to 5500087-10 © Copyright 2002 by Black Box Corporation.
1 Introduction Ethernet Remote Bridge/Router The Ethernet remote bridge/router provides IP and IPX routing combined with a protocol transparent bridge. This bridge/router combination is often the best solution to linking remotely located LANs where most of the traffic is IP or IPX with smaller amounts of traffic from other protocols such as NetBIOS or DEC LAT. The Ethernet bridge/router supports the widely implemented Routing Information Protocol, otherwise known as RIP.
Introduction ARP—Address Resolution Protocol A protocol called ARP (Address Resolution Protocol) is used to determine the MAC address of a particular IP address. The MAC (Medium Access Control) address is unique predefined number for each device on the LAN. The manufacturer of the device assigns MAC addresses. The IP address for each device is assigned by the network administrator according to the network structure.
Introduction • Local router will look in its ARP cache to find the MAC address of the destination router as determined by the IP address in the routing table. • Local router will rebuild the complete frame with a new MAC header indicating the MAC address of the destination router. The local router does not alter the destination IP address, so the destination IP address will still be the IP address of the destination station.
Introduction Time to live The time to live section is used to prevent a frame from traversing the network forever. This field contains a number (maximum 255) that is set when the frame is originally generated. Each time the frame is passed through the bridge/router, the bridge/router will decrement the time to live by two. When the time to live reaches zero, the frame is discarded. Header Checksum The header checksum is used to verify the data in the IP header.
Introduction Time Stamps The time stamp option is used to record the time at which the IP frame passed through each router on its way to the destination station. ICMP Messages Internet Control Message Protocol (ICMP) messages are used to perform station and router protocol participation. ICMP messages are passed between routers, or between routers and stations. There are several different messages, as discussed below.
Introduction RIP—Routing Information Protocol The most important function of the IP protocol is routing. IP routers constantly exchange information keeping their routing tables up to date. A method of communication is required to ensure compatibility between all IP routers in the network. RIP is the portion of the IP protocol that is used for router communication. Route Tables Each router will maintain a table of network addresses and the appropriate action to take with an IP frame it receives.
Introduction IPX Routing and The Ethernet Remote Bridge/Router The Ethernet bridge/router may be used to route between IPX networks. Novell Netware uses a suite of protocols for LAN communications. The Novell protocols include IPX, SPX, RIP, SAP, plus others, and operate at layers 3 and above. These protocols, their relationship with each other, and the general operation of a Novell network are discussed in this section.
Introduction Network Addresses The Network Number addresses the network. All stations on the same “network” will have the same Network Number. Note that a network could be a single segment, or multiple segments joined by either bridges or repeaters. In IPX internetworks, routers must be used to join different networks together. Node Addresses The Node Number identifies the individual stations in a Network. In IPX devices, this address is assigned automatically and is identical to the MAC address.
Introduction The checksum is a hold-over field from the XNS model used by Novell. In the original XNS header, the checksum was used; however, Novell decided that the MAC trailer CRC was enough protection and the IPX header checksum need not be used. Therefore the IPX checksum is permanently set to FFFF. The length field indicates the total length of the IPX packet. Note that the data portion can be any length up to 546 bytes, so the length field is needed in the header.
Introduction When a Client or Server notices that a Server from its known Server list has missed a broadcast (it should get one about every 30 seconds), it starts up a counter, and when the Server has missed 3 broadcast intervals (about 180 seconds) that Service is removed from the known Server list. In this way Servers that crash or go off-line for any reason are aged out of the network. SAP Requests Sometimes Clients will need to find out if a specific Server is available.
Introduction RIP/X Broadcasts A RIP broadcast is sent out by IPX routers every 30 seconds or so. Each broadcast may contain information on up to 15 different routes (to 15 different networks). If a router knows of more than 15 networks it will send out two (or more) broadcasts. Note that to spread the network overhead a router will stagger the generation of RIP/X and SAP broadcasts.
Introduction Bridging and the Ethernet Remote Bridge/Router The bridge portion of the Ethernet remote bridge/router is an Ethernet Media Access Control (MAC) level bridge providing an efficient means of interconnecting IEEE 802.3 Local Area Networks supporting a choice of standard Ethernet (10Base5), Thin Ethernet (10Base2) and Twisted Pair (10BaseT) interfaces.
Introduction The bridge/router captures each frame and looks at the source address contained within the Ethernet frame. Since the bridge/router knows which LAN segment the frame was received from, it can determine that this station must be located on this segment. As a result, it has just learned the location of the station. This process will continue for the period defined by the Forwarding Delay option, and in this fashion the first stage of the LAN address table is built.
Introduction Aging Timer During the bridging process, the filter table is built giving the location (bridge port or LAN segment) of known Ethernet addresses. The table would become quite large, eventually reducing performance, if stations were added, removed, or moved without the old information being purged periodically. Performance is affected since the larger the table, the more time it will take to process an incoming frame.
Introduction Ethernet Bridge/Router Feature Definitions Telnet A Telnet LAN station or another Ethernet bridge/router has the ability to connect to the Operator Interface of any Ethernet bridge/router supporting the Telnet feature. With the Telnet feature, all Ethernet bridge/routers on a network may be managed from a single point. Once a connection is established, all of the menus of the other bridge/router are now available on the bridge/router that initiated the connection.
Introduction 7 6 5 4 Compression Ratio 3 2 1 0 Pre-compressed Binary Spreadsheet C Source ASCII Post Script Database Graphic File Type Figure 1 - 5 Typical Compression Ratios by File Type Data compression will give a 56/64 Kbps link an effective throughput range from 112/128 Kbps when transferring binary files, to 364/384 Kbps when transferring graphic files.
Introduction Operating Software Upgrades The Ethernet Bridge/Router includes flash memory, that allows new system code to be downloaded using the Trivial File Transfer Protocol (TFTP). This allows software updates to be performed quickly and painlessly from a host server (with TFTP capabilities) on the network. The Bridge/Router also allows the downloading of software updates by using a direct management port connection and the ZMODEM transfer protocol.
2 Link Interface Reference Pinout Information The router is manufactured with four different WAN link modules: V.35, LXT411 CSU/DSU, Universal WAN or T1/E1. The type installed may be determined from the label on the WAN link output connector. V.35 Module: The V.35 link interface is provided as a DB25 connector on the back of the bridge/router, so an interface converter is needed to convert to the standard V.35 connectors.
Link Interfaces Reference Changing the link speed within the menu system of the router changes the clock output speed that is generated on the DTE Terminal Timing pins on the link interfaces. Console Connector The console connector on the router is a DCE interface on a RJ45 pinout. The supplied DB9 to RJ45 converter should be used to connect to the DB9 connector of a DTE terminal. This connection will then provide access to the built-in menu system.
Link Interfaces Reference The LXT411 CSU/DSU link connection is set to operate at 64 Kbps by default. The link may be set to 56 Kbps via the software menus if required. When two CSU/DSU link routers are to be connected via a leased line in a back to back set-up, the unit must be set to 56 Kbps link speed and a null-modem crossover cable used for the connection.
Link Interfaces Reference V.35 Link Pinouts The connector shown here and pinouts described here correspond to the connector labeled “V.35” on the back of the router. 1 13 25 14 DB25 Female DTE DB25 Contact Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 M.
Link Interfaces Reference V.35 Null-Modem Cable Configuration Figure 2 - 5 V.35 Null-Modem Cable The connecting cable must be a shielded cable. Circuits which are paired (contain an (A) and (B) reference) should be connected to twisted pairs within the connecting cable. This cable is needed when it is necessary to connect two units back-to-back and a set of modems is not available.
Link Interfaces Reference V.24 & RS232C Link Pinouts The pinouts described here correspond to the RS232/ V.24 mode for a Universal WAN router. DB25 Female DTE Contact Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 CCITT Circuit Number 101 103 104 105 Circuit AA BA BB CA 107 102 109 CC AB CF 114 DB 115 141 DD 108.
Link Interfaces Reference V.11 & X.21 Link Pinouts The pinouts described here correspond to the V.11/X.21 mode for a Universal WAN router. Note: A DB25 to DB15 pin converter will be required to connect to V.11/X.21 service. Contact Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 X.
Link Interfaces Reference RS442 & RS530 Link Pinouts The pinouts described here correspond to RS530 mode for a Universal WAN router.
Link Interfaces Reference RS232 Null-Modem Cable Configuration Figure 2 - 9 RS232 Null-Modem Cable The connecting cable must be a shielded cable. This cable is needed when it is necessary to connect two units back-to-back and a set of modems is not available. Note that this cable specifies DB25 connectors on each end to allow direct connection to the link interface connector on each unit. The link speed must be defined for each of the two units.
Link Interfaces Reference RS530 Null-Modem Cable Configuration DB25 MALE DB25 MALE 1 Shield 2 Transmitted Data (A) 14 Transmitted Data (B) 3 3 2 Transmitted Data (B) 14 DCE Ready (A) Request To Send (A) 6 DCE Ready (B) 22 Clear To Send (A) Clear To Send (A) 5 Clear To Send (B) 13 13 Clear To Send (B) 6 Received Data (A) Transmitted Data (A) Received Data (A) 19 Request To Send (B) 5 1 Received Data (B) 16 16 Received Data (B) 4 Shield DCE Ready (A) Request To Send (A) 22 DCE Read
Link Interfaces Reference V.11/X.21 Null-Modem Cable Configuration Figure 2 - 11 V.11/X.21 Null-Modem Cable The connecting cable must be a shielded cable. Circuits which are paired (contain an (A) and (B) reference) should be connected to twisted pairs within the connecting cable. This cable is needed when it is necessary to connect two units back-to-back and a set of modems is not available.
Link Interfaces Reference WAN Link Control-Signal Operation CTS flow control is not supported. 1) When a call is made to the bridge/router, RI will be asserted by the modem. The bridge/router responds by driving DTR and RTS high to signal to the partner’s modem that it is ready to establish communications. The bridge/router then waits (for the duration of the CD Wait Time, default 60 seconds) for the partner’s modem to respond with incoming CD and DSR signals driven high.
3 Event Logs The Ethernet bridge/router generates event logs for various functions performed by the bridge/router. All of the event logs are stored in the internal event log file, which is accessible through the Network Events menu. Certain event logs are classified as alarms because they are deemed to be of higher urgency. Alarm logs are indicated by an asterisk (“*”) at the start of the alarm text and are printed on the ALARM line on the menu system as well as being stored in the event log.
Event Logs DHCP: pool deleted due to mismatch with new IP address Generated when the address of this device is changed , rendering the block of addresses assigned to the DHCP pool invalid. DHCP: Requested address unavailable Generated when the address requested by a client is unavailable DHCP services – declined. Address declined by client, mark it as unavailable.
Event Logs IPX: X, unknown SAP packet type received Generated when the device receives an invalid SAP packet. IPX: X, demand RIP failed Generated when this device reaches the end of the attempts to negotiate demand RIP for the IPXCP connection. After demand RIP has failed, the normal RIP and SAP updates will occur. LCP X authenticating peer with CHAP Generated when this device is using CHAP to authenticate the peer (remote) device.
Event Logs Link X CSU/DSU: Connected Generated when the CSU/DSU link module has established a connection to the remote partner CSU/DSU. Link X CSU/DSU: Initialized Generated when the CSU/DSU link module has completed initialization and has established communications with the router. Link X CSU/DSU: Line ERROR Generated when the CSU/DSU link module is in an unknown error state. Link X CSU/DSU: Loopback Ended Generated after the CSU/DSU link module completes a loopback test.
Event Logs LMI discarding STATUS on link X – Enquiries not started Generated when the bridge/router discards a Status message received from the frame relay network on a link that the bridge/router has not yet started the Local Management Interface. No NCP's open, tearing link down Generated when a PPP link does not have a Network Control Protocol operating. This may be due to BCP, IPCP, and IPXCP being disabled, or the NCP connection was not negotiated to completion.
Event Logs Starting IPCP negotiation with Generated when the Internet Protocol Control Protocol negotiation has been initiated with the remote site device associated with the stated remote site profile. Starting IPXCP negotiation with Generated when the Internet Packet Exchange Control Protocol negotiation has been initiated with the remote site device associated with the stated remote site profile.
Event Logs Alarm logs: * Auto-learning of LMI type on link X unsuccessful Generated when the LMI type on a link is not successfully auto-learned. * Bad internal block checksum detected Generated when power up diagnostics finds a fault in the internal block of the EEPROM. * Closing remote site X (call limit) Generated when the specified number of calls has been exceeded. * Closing remote site X (frame relay closing) Generated due to the frame relay protocol being disabled on the bridge/router.
Event Logs * Closing remote site X (resumption failure) Generated due to failure to resume a suspended connection. * Closing remote site X (scheduled down) Generated due to time-of-day schedule deactivation of the connection. * Closing remote site X (suspension timeout) Generated due to reaching maximum time that the connection may be suspended. * Closing remote site X (usage limit) Generated due to reaching usage limit for this 24 hour period. * Config.
Event Logs * Download aborted – Incomplete file Generated when a TFTP download is aborted before the file transfer is complete * Download aborted – Invalid FCS Generated when there is a checksum failure after a file download. * Download aborted – Incompatable boot code Generated when the operating code file downloaded is incopatible with the boot code in this device. The updated boot code software must be loaded before the operating code can be updated.
Event Logs * FTP server added to firewall The IP address of the FTP server added to the table of services available through the firewall. * FTP server removed from firewall The IP address of the FTP server removed from the table of services available through the firewall. * IP protocol parameters initialized Generated when IP protocol communications to a remote site configured for frame relay are negotiated successfully.
Event Logs * Link X, DLCI Y attached to remote site Generated for frame relay applications when a connection has been made for the DLCI associated with the remote site alias. * Link X down Generated when a WAN link goes down. * Link X down to Generated when a WAN link connection to the specified remote site goes down. * Link X – LMI Error Threshold exceeded Generated when the defined error threshold has been exceeded on the specified link.
Event Logs * NAT table full Generated when no more ports are available for Network Address Translation. * No available remote site for learned DLCI Generated when, during Frame Relay Auto-learning, the remote site table is filled, no space is available to create another entry. The user must manually edit the table to remove some remote site profiles before another entry can be made.
Event Logs * Remote Site still closing Generated when a connection is attempted to a remote site whose link is still in the process of being disconnected. * Remote site suspended Generated when the connection to the specified remote site has been suspended. * Remote site terminated Generated when the connection to the specified remote site has been terminated for connection management.
Event Logs * (T1/E1) Yellow Alarm Off Yellow Carrier Failure Alarm is being turned off – alarm cleared when Yellow Alarm indicator signal from far end stops. * Telnet server removed from firewall The IP address of the Telnet server removed from the table of services available through the firewall. * Telnet server added to firewall The IP address of the Telnet server added to the table of services available through the firewall. * TFTP: Abort.
Event Logs * Unable to route!! UDP failure Generated when the device tried to open an already open UDP channel, causing IP routing to fail. * Unknown call type on remote site The attempted call is not a Frame Relay or PPP leased line call. Possible cause is a remote site profile being deleted while a connection attempt is being made. * WWW (HTTP) server removed from firewall The IP address of the WWW (HTTP) server removed from the table of services available through the firewall.
Event Logs PPP security logs: CHAP authentication failure so terminate link. Generated when the CHAP authentication sent by this router in response to a request from a remote site is rejected. CHAP failed for Generated when the remote site router failed a CHAP authentication request from this router. The remote site name is displayed if known.
4 Programmable Filtering Programmable filtering gives the network manager the ability to control under what conditions Ethernet frames are forwarded across bridge or bridge/router ports. There are many reasons why this might need to be accomplished, some of which are security, protocol discrimination, bandwidth conservation, and general restrictions. To reach a specific filtering goal, there is usually more than one possible filter expression that may be used.
Programmable Filtering Security—“Filter if Destination” Filter if Destination is a function that allows you to filter an Ethernet frame based on the destination of its address. If the destination address equals the address that the Filter if Destination function has been applied to, the frame is filtered.
Programmable Filtering Security—“Filter if Source” Filter if Source is a function that allows you to filter an Ethernet frame if the source address of the frame equals the address that the Filter if Source function has been applied to. Example: Assume that a Personal Computer is located on segment 1 on the local bridge/router. This station is a community station that various departments may use for general processing.
Programmable Filtering 8 The bridge/router will prompt you for the LAN that the station is located on; enter the name of the partner bridge/router LAN (LAN345678, for example). Note that the Status of the address is marked as [present], the location is updated to LAN345678 and the Permanent entry is [enabled]. 9 Enter a 3 to [enable] the “Filter if Source” parameter. The edit screen will be updated to show the new information.
Programmable Filtering 4 From the MAC ADDRESS FILTERS MENU, make sure that the Filter Operation is currently set to “negative”. This will cause the MAC Address Filters specified to be used for forwarding frames with the specified MAC addresses. 5 From the MAC ADDRESS FILTERS MENU, enter a 1. This will place you at the first EDIT MAC ADDRESS FILTER MENU screen. At the prompt enter the MAC address for which you want to specify the filter.
Programmable Filtering 2 From the CONFIGURATION MENU, enter an 8. This will place you at the FILTER SET-UP MENU, where access to the individual filtering menus is obtained. 3 From the FILTER SET-UP MENU, enter a 1. This will place you at the MAC ADDRESS FILTERS MENU, where access to the MAC Address filters is obtained. 4 From the MAC ADDRESS FILTERS MENU, make sure that the Filter Operation is currently set to “negative”.
Programmable Filtering Pattern Filter Operators The following operators are used in creating Pattern filters and will be discussed further in the following pages. For additional information refer to the octet locations diagrams at the back of this manual. Each octet location may contain a HEX value. - offset Used in pattern filters to determine the starting position to start the pattern checking.
Programmable Filtering Bridge Pattern Filtering Protocol Discrimination Protocol discrimination may be required to prevent or limit the protocols that may traverse a bridged Local Area Network. In Local Area Networks there may be many different Network and Transport layer protocols that coexist on the same physical media. TCP/IP, DECNET, and XNS are just a few of the common protocols in use today.
Programmable Filtering IP, and no more This example performs just the opposite function to the above example. Only IP packets will be allowed to be passed across the bridged network. For this function there must be a method to prevent all but IP packets from being filtered. For this the NOT (“~”) logical operator is used. The NOT operator specifies that the expression has to be FALSE before the frame is filtered.
Programmable Filtering Local Area Transport (LAT) The Local Area Transport (LAT) protocol is used exclusively by DEC for terminal access between DEC hosts and terminal servers located on an Ethernet network. This example is similar to the Internet Protocol example described previously. The protocol type field value that is used for LAT frames is equal to 6004.
Programmable Filtering DEC DEC uses protocol types 6000 to 600F, and although some are undefined, a simple filter mask can be created to filter all DEC traffic. Filter all DEC The mask to filter all DEC traffic would be: 12-600X The X is a variable representing the last four bits (a nibble) of the type. This will effectively filter all Ethernet frames that contain a protocol type of 6000 through to 600F. All 16 possible combinations are covered.
Programmable Filtering General Restrictions Bridge Filter Masks may be created to generally restrict access for various purposes. Some of these purposes may be to filter specific combinations of information. This section will generally depict masks that may be created to control traffic across the bridged LAN network. Internet Addresses Within the Internet Protocol, there exist two address fields that are designated the Source and Destination Internet Addresses.
Programmable Filtering Mask Combinations Mask combinations may be required to ensure that a frame is sufficiently qualified before the decision to filter is made. The qualification a frame must go through before a filter decision is made depends on the reason for the filter. Nonetheless, a few examples below have been provided that should aid in the creation of a mask that may require that extra little bit of qualification.
Programmable Filtering IP Router Pattern Filtering Pattern filtering may be used on any portion of the IP frame. IP pattern filtering behaves the same as bridge pattern filtering, except the start of the IP frame is offset 0, because the IP router function of the bridge/router handles only the IP frame itself. IP pattern filtering may use any combination of filtering operators as described in the bridge pattern filters.
5 Frame Formats This appendix provides octet locations for the various portions of three of the common Ethernet frames. When creating pattern filters these diagrams will assist in the correct definition of the patterns. The offset numbers are indicated by the numbers above the frame representations. Note the differences in the TCP/IP and Novell frames when bridging and when routing.
Frame Formats ETHERNET TYPE CODES Type Code Description 0800 DOD IP 0801 X.75 Internet 0804 Chaosnet 0805 X.
Frame Formats Octet Locations on an IPX Routed Novell Netware Frame Octet Locations on a Bridged XNS Frame 5500100-10 63
