Cabletron Systems 9A128-01 manuale d’uso

9A128-01 ™ Management Module Guide f or Micr osoft ® Windo ws ™ Title Page Cabletr on Systems[...]

i Notice Cabletron Systems r eserves the right to make changes in specifications and other information contained in this document without prior notice. The reader should in all cases consult Cabletr on Systems to determine whether any such changes have been made. The hardwar e, firmware, or software described in this manual is subject to change w[...]

ii AppleT alk, Apple, Macintosh, and T okenT alk are register ed trademarks; and Apple Remote Access and EtherT alk are trademarks of Apple Computer , Inc. SmartBoost is a trademark of American Power Conversion ST is a register ed trademark and C++ is a trademark of A T&T Banyan and VINES are r egistered trademarks of Banyan Systems, Inc. cisco[...]

iii ANNEX, ANNEX-II, ANNEX-IIe, ANNEX-3, ANNEX-802.5, MICRO-ANNEX-XL, and MICRO- ANNEX-ELS are trademarks of Xylogics, Inc. MAXserver and Xyplex are trademarks of Xyplex, Inc. Restricted Rights Notice (Applicable to licenses to the United States Government only .) 1. Use, duplication, or disclosure by the Government is subject to r estrictions as s[...]

iv[...]

v Contents Chapter 1 Intr oduction Using This Guide .......................................................................................................... 1-1 Related Reading ............................................................................................................ 1-2 Software Conventions .....................................[...]

Contents vi Configuring Connections ............................................................................................. 3-4 Adding a New Connection ................................................................................... 3-4 Deleting a Connection .................................................................................[...]

1-1 Chapter 1 Intr oduction How to use this guide; getting help; softw are conv entions; related reading; fir mware v ersions W elcome to the Cabletron Systems MMAC-Plus™ Remote Management for the 9A128-01™ User ’s Guide . W e have designed this document to serve as a simple refer ence guide for using MMAC-Plus Remote Management for the 9A12[...]

Introduction 1-2 Related Reading Installing and Using SPECTRUM Element Manager Guide , Using MMAC+ Remote Management, User ’s Guide and SPECTRUM Element Manager T ools Guide . Chapter 1, Introduction , provides a list of r elated documentation, describes certain software conventions, and shows you how to contact Cabletr on Systems’ Global Call [...]

Software Con ventions 1-3 Introduction Software Con ventions The SPECTRUM Element Manager user interface contains a number of elements which are common to most windows and which operate the same r egardless of which window they appear in. A brief description of some of the most common elements appears below; note that the information provided her e[...]

Introduction 1-4 Getting Help Location Displays the user-defined location of the device. The location is enter ed through the System Group window; see the Generic SNMP User ’ s Guide for details. MA C Address Displays the manufacturer -set MAC address of the channel through which SPECTRUM Element Manager is communicating with the device. MAC add[...]

Getting Help 1-5 Introduction From the Help menu accessed fr om the Module V iew window menu bar , you can access on-line Help specific to the Module V iew window , as well as bring up the Chassis Manager window for refer ence. Refer to Chapter 2 for information on the Module V iew and Chassis Manager windows. Getting Help fr om the Cabletron Syst[...]

Introduction 1-6 Fir mw are V ersions Suppor ted Firmware V ersions Supported SPECTRUM Element Manager support for the 9A128-01 module has been tested against firmware versions up to 2.10.13. If you have an earlier version of firmwar e and experience problems, contact Cabletr on Systems Global Call Center for upgrade information. NO TE As a gener[...]

2-1 Chapter 2 The 9A128-01 Module Vie w Inf or mation display ed in the Module View windo w; the Chassis Manager window; hub management functions The 9A128-01 Module V iew window is the main scr een that immediately informs you of the current configuration of your 9A128-01 via a graphical display of the two bridge ports and the FDDI A and B ports [...]

The 9A128-01 Module View 2-2 Viewing Module Inf ormation Vie wing Module Information The 9A128-01 Module V iew window ( Figur e 2-2 ) provides a graphic repr esentation of the 9A128-01, including a color-coded port display which immediately informs you of the current configuration and status of each port. Figure 2-2. 9A128-01 Module V iew W indow [...]

Viewing Module Inf ormation 2-3 The 9A128-01 Module View IP The Module V iew window title displays the device’s IP (Internet Protocol) Address; this will be the IP address you have used to create the 9A128-01 module in the Chassis Setup window , or the IP addr ess used to create the device icon. IP addresses ar e assigned via Local Management, an[...]

The 9A128-01 Module View 2-4 Viewing Module Inf ormation Time The current time, in a 24-hour hh:mm:ss format, set in the 9A128-01’s internal clock. Date The current date, in an mm/dd/yy format, set in the 9A128-01’s internal clock. Menu Structure By clicking on various areas of the 9A128-01 Module V iew display , you can access menus which prov[...]

Viewing Module Inf ormation 2-5 The 9A128-01 Module View Figure 2-3. 9A128-01 Module V iew Menu Structur e The Device Men u From the Device Menu at the Module V iew window menu bar , you can access the following selections: • Device T ype... , which displays a window containing a description of the device being modeled: 9A128-01, A TM/FDDI Bridge[...]

The 9A128-01 Module View 2-6 Viewing Module Inf ormation • A TM Connections , which launches the window that allows you to view and configure Permanent V irtual Circuits (PVCs) for the 9A128-01’s front panel A TM interfaces. For more information about configuring PVCs, see Chapter 3, A TM Configuration . • Power Supply ... which launches t[...]

Viewing Module Inf ormation 2-7 The 9A128-01 Module View • Connect will display the each FDDI port’s connection status. • LER Estimate will display the cumulative long term average of the bit error rate for each FDDI port, which repr esents the quality of the physical link. For more information on the bridge and FDDI port display options avai[...]

The 9A128-01 Module View 2-8 Viewing Module Inf ormation • Module T ype... , which brings up a window containing a description of the 9A128-01 board; see V iewing Hardware T ypes , page 2-13 . • Performance Graph... , which visually displays performance between all bridging ports on the 9A128-01; see Chapter 5, Bridging . • Spanning T ree... [...]

Viewing Module Inf ormation 2-9 The 9A128-01 Module View Initially , each FDDI port on the 9A128-01 will by default display its current connection status (defined below); to change this status display , select the Connect or LER Estimate option on the Port Status menu, as described in the following section. Note that the status display of the brid[...]

The 9A128-01 Module View 2-10 Viewing Module Inf ormation Bridge P or t State If you choose the Bridge Port State mode, a bridge port is considered: • FWD (Forwarding) if the port is on-line and forwar ding packets across the 9A128-01 from one network segment to another . • DIS (Disabled) if bridging at the port has been disabled by management;[...]

Viewing Module Inf ormation 2-11 The 9A128-01 Module View FDDI port status view options are: Connection State The Connection State port display form indicates the port’s connection status: • CON (connecting): the port is trying to establish a link, but has not yet been successful. Ports which are not connected and which have not been disabled b[...]

The 9A128-01 Module View 2-12 Viewing Module Inf ormation FDDI P or t Status Color Codes FDDI port status color codes always reflect the port’s connection status, even when the LER Estimate port display form has been selected. Under that color coding scheme: • CON (Connecting) = yellow • ACT (Active) = green • SBY (Standby) = r ed • DIS [...]

Viewing Module Inf ormation 2-13 The 9A128-01 Module View Figure 2-5. Chassis Manager W indow Viewing Har dware T ypes In addition to the graphical displays described above, menu options provide specific information about the physical characteristics of ports in the 9A128-01, as well as information about the 9A128-01 module itself. Device T ype Ch[...]

The 9A128-01 Module View 2-14 Viewing Module Inf ormation Figure 2-7. Module T ype W indow Viewing I/F Summary Inf ormation The I/F Summary option available from the Device menu lets you view statistics (displayed both graphically and numerically) for the traffic pr ocessed by each network interface on your device. The window also provides access [...]

Viewing Module Inf ormation 2-15 The 9A128-01 Module View UpTime The UpT ime field lists the amount of time, in a days, hh:mm:ss format, that the device has been running since the last start-up. Index The index value assigned to each interface on the device. T ype The type of the interface, distinguished by the physical/link protocol(s) r unning i[...]

The 9A128-01 Module View 2-16 Viewing Module Inf ormation Raw Counts The total count of network traffic r eceived or transmitted on the indicated interface since device counters were last r eset. Raw counts are provided for the following parameters. In Octets Octets received on the interface, including framing characters. In Packets Packets (both [...]

Viewing Module Inf ormation 2-17 The 9A128-01 Module View management backplane; 100 Mbps for FDDI; or 155 Mbps for A TM). Load is further defined by the following parameters. In Octets The number of bytes received by this interface, expr essed as a percentage of the theor etical maximum load. Out Octets The number of bytes transmitted by this inte[...]

The 9A128-01 Module View 2-18 Viewing Module Inf ormation Three informational fields appear in the upper portion of the window: Description Displays the interface description for the currently selected port: Ctr on SMB 1, Ctron SMB 10, FDDI, or A TM. Address Displays the MAC (physical) address of the selected port. T ype Displays the interface typ[...]

Viewing Module Inf ormation 2-19 The 9A128-01 Module View P ackets Received (Receiv ed only) Displays the number of packets received by the selected interface. T ransmit Queue Siz e (T ransmit only) Displays the number of packets currently queued for transmission fr om this interface. The amount of device memory devoted to buffer space, and the tra[...]

The 9A128-01 Module View 2-20 Managing the Hub 2. Drag to Find Sour ce Address... . The f ollowing window will appear . Figure 2-10. Find Source Address W indow 3. In the te xt field in the middle of the windo w , enter a valid MA C address in He x f or mat and then click . If the address is found in the 802.1d Bridge Filtering Database, the port [...]

Managing the Hub 2-21 The 9A128-01 Module View Figure 2-1 1. New T ime W indow 3. Enter the new time in a 24-hour hh:mm:ss f ormat, either by highlighting the field you wish to change and using the up and do wn arrow buttons , or by simply entering the new v alue in the appropr iate field. 4. Click on to sav e your changes , or on to cancel. T o [...]

The 9A128-01 Module View 2-22 Managing the Hub networks connected to the bridge. When you enable a port, the port moves from the Disabled state through the Learning and Listening states to the Forwar ding state; bridge port state color codes will change accordingly . T o enable or disable a bridge port: 1. Click on the appropriate Bridge P or t to [...]

3-1 Chapter 3 A TM Configuration Viewing connection data; configuring P ermanent Vir tual Circuits (PVCs); adding and deleting connection entries The A TM interfaces provided by the 9A128-01 module provides the connectivity that allows you to merge A TM network segments with traditional LAN technologies via the FDDI FNB backplane. Current version[...]

A TM Configuration 3-2 Accessing the A TM Connections Window Figure 3-1. The Current A TM Connections W indow The Current A TM Connections window provides the following information about the device’s A TM connections: Connection Data The Connection Data fields provide the following information about each A TM interface available on the device: [...]

Accessing the A TM Connections Window 3-3 A TM Configuration Settings The Settings portion of the window contains a list box which displays information about each of the currently configur ed PVCs, as well as the fields used to configure new connections: I/F The device interface on which the PVC was configured. VPI Displays the V irtual Path I[...]

A TM Configuration 3-4 Configuring Connections Selecting the Add button either adds a new connection or modifies an existing one, using the parameters entered in the fields below the list box. A confirmation window will appear for both additions and modifications. Selecting the Delete button deletes the selected connection; a confirmation wi[...]

Configuring Connections 3-5 A TM Configuration 4. In the Encapsulation T ype field, clic k on the down arrow located to the right of the field, and drag do wn to select the desired encapsulation type. Current v ersions of 9A128-01 fir mware use 802.3 VC-based multiple xing f or br idging protocols (designated VC MUX 802.3 Bridged); future vers[...]

A TM Configuration 3-6 Configuring Connections[...]

4-1 Chapter 4 FDDI Mana g ement Configuration; connection policy; station list; and perf or mance The FDDI menu lets you access windows to view FDDI configuration, connection policy , station list, and performance with respect to the single Station Management (SMT) entity which provides each device’s connectivity to the FDDI FNB backplane. SMT [...]

FDDI Management 4-2 Configuration • Station List — W ith this window you can see the configuration of the ring on which the SMT entity resides, including number of nodes, node addr esses (both Canonical and MAC), node class, and current ring topology . • Performance — This window lets you view the number of frames transmitted and received[...]

Configuration 4-3 FDDI Management MA C State This field indicates the current state of the selected module’s MAC component. (The RMT component of SMT monitors MAC operation and takes actions necessary to aid in achieving an operational ring.) Possible states are: Not A vailable There is no MAC on the FDDI ring associated with the SMT entity , o[...]

FDDI Management 4-4 Configuration to remove fr om the ring and conduct a self-test. If the ring does not recover , each subsequent upstream station will be forced to r emove from the ring and conduct self-tests until the problem has been corr ected. While the test is being conducted, ring management re-enters the isolated state. SMT V ersion Displ[...]

Configuration 4-5 FDDI Management Concentrator M P or ts This field displays the number of Master (M) ports on the device that are associated with the selected SMT entity . A Master port is a port that provides a connection for Single Attachment Station (SAS) devices to the FDDI network. The 9A128-01 does not support M ports, so this field will [...]

FDDI Management 4-6 Connection P olicy Connection P olicy The SMT Connection Policy determines which types of connections are allowed among the four FDDI port types: A, B, M (Master), and S (Slave). FDDI protocol forbids Master—>Master connections; all other connection types are legal, although some are consider ed to be undesirable. The Conne[...]

Connection P olicy 4-7 FDDI Management Each device has its own connection policy; however , when two devices attempt to connect, their combined established connection policies dictate the connections that will be allowed. In an attempted connection between two nodes, the most lenient policy will determine whether the connection (as long as it is le[...]

FDDI Management 4-8 Station List Station List The Station List illustrates the configuration of the ring associated with the currently selected SMT entity , including number of nodes on the ring, node addresses (both Canonical and MAC), node class, and ring topology . Figure 4-4. The Station List W indow The Station List provides the following inf[...]

Station List 4-9 FDDI Management Stations P anel The Stations Panel displays a list of the stations on the ring to which the selected SMT is connected, in ring sequence from the MAC, along with each station’s node class and current topology . Note that the information displayed in the Station List is static once the window is opened; for updated [...]

FDDI Management 4-10 P erf or mance P erf ormance The Performance window , Figure 4-5 , pr ovides graphical and numeric performance statistics for the selected SMT entity , including: • T ransmit Frames • Receive Frames • Frame Errors • Lost Frames • Ring Ops Figure 4-5. Performance W indow Statistics are displayed in thr ee ways: • By [...]

P erf or mance 4-11 FDDI Management A vailable statistics are: T ransmit Frames The number of frames transmitted by the MAC associated with the SMT during the chosen interval. Receive Frames The number of frames received by the MAC associated with the SMT during the chosen interval. Frame Error s The number of error frames detected by the MAC assoc[...]

FDDI Management 4-12 P erf or mance[...]

5-1 Chapter 5 Bridging Bridge management ov er view; the Bridge Status window; enab ling and disabling bridging; Br idge P erf or mance Graphs; bridge detail breakdown; the Bridge Spanning T ree window; changing bridge Spanning T ree parameters; the Filtering Database window; configuring the filtering database W ith SPECTRUM Element Manager ’s [...]

Bridging 5-2 The Bridge Status Windo w The Bridge Status Window The Bridge Status window provides you with basic information about the curr ent status of bridging across your 9A128-01. Color -coding of each port display allows you to quickly ascertain the status of each interface. The Bridge Status window also lets you access further windows to con[...]

The Bridge Status Windo w 5-3 Bridging Up Time At the top of the Bridge Status window , you can see the time period (in a days, hh:mm:ss format) that has elapsed since the selected module was last reset or initialized. Bridge State on Interface Indicates the state of bridging over the port interface. Note that this state (and its corresponding colo[...]

Bridging 5-4 Configuring Duplex Modes • A Module T ype window that contains a description of the 9A128-01 module, see V iewing Hardware T ypes in Chapter 2 for more information. • A Bridge Performance Graph that displays statistics for traffic acr oss the entire bridge (see Bridge Statistics , page 5-6 ). A Performance Graph window is also av[...]

Enabling and Disab ling Bridging 5-5 Bridging Figure 5-2. The Duplex Modes W indow The main portion of the Duplex Modes window consists of a list of the interfaces available on the 9A128-01 module and their current Full Duplex state: ON indicates that Full Duplex mode has been enabled for the selected interface; OFF indicates that it has not; N/A i[...]

Bridging 5-6 Bridge Statistics T o enable or disable bridging at all ports from the Bridge Status window: 1. Click on to displa y the br idge menu. 2. Drag do wn to Enable Bridge to restar t br idging across all interf aces, or Disable Bridge to halt bridging across all interfaces . Y ou can also disable bridging across all ports or for an individu[...]

Bridge Statistics 5-7 Bridging 2. Drag do wn to Perf ormance Graph... , and release. The Bridge P erf or mance Graph windo w , Figure 5-3 , will appear . (The individual por t Bridge P erf or mance Graph windows are similar , e xcept that they displa y a gr aph applicable to the selected interf ace.) Figure 5-3. Bridge Performance Graph T o access [...]

Bridging 5-8 Bridge Statistics Filtered (Magenta) Filtered The total number of frames filtered by the bridge, at the device or port level. Nothing The Filtered scale is not curr ently measuring the number of packets filtered by the bridge. T otal Errors (Red) T otal Errors The total number of errors experienced by all bridging interfaces on the s[...]

Bridge Statistics 5-9 Bridging Figure 5-4. The Bridge Detail Breakdown W indow The following information is available for the network segments connected to each of the bridge ports on the 9A128-01. The information is expressed both numerically and in pie charts. Each port’s network segment has a corresponding color for its statistics or pie chart[...]

Bridging 5-10 Bridge Statistics Figure 5-5. The Bridge Port Detail Breakdown W indow The following information is available for each bridge interface on the 9A128-01; the information is expressed both numerically and in pie charts: Forwarded to The number of frames forwarded by the selected bridge interface to each other interface on the bridge. Fo[...]

Bridge Statistics 5-11 Bridging Figure 5-6. Interface Statistics W indow Three informational fields appear in the upper portion of the window: Description Displays the interface description for the currently selected port. Address Displays the MAC (physical) address of the selected port. T ype Displays the interface type of the selected port. The [...]

Bridging 5-12 Using Source Addressing Discarded Displays the number of packets which were discar ded even though they contained no errors that would pr event transmission. Good packets are typically discarded to fr ee up buffer space when the network becomes very busy; if this is occurring routinely , it usually means that network traffic is overw[...]

Using Source Addressing 5-13 Bridging Figure 5-7. The Port Source Addr esses W indow The Port Source Addresses window displays the MAC addr esses of all devices that have transmitted packets that have been forwarded thr ough the selected bridging interface during the last cycle of the Filtering Database’s defined ageing timer (learned addresses [...]

Bridging 5-14 Bridge Spanning T ree 2. T ype in the new Ageing Time (allo wab le range is 10 to 1,000,000 seconds; the def ault is 300 seconds). 3. Click to accept the new Ageing Time , or click to e xit the window without making changes . Bridge Spanning T ree The Bridge Spanning T ree window allows you to display and modify the selected module’[...]

Bridge Spanning T ree 5-15 Bridging Figure 5-9. Bridge Spanning T ree W indow Configuring the Bridge Spanning T ree Window The Bridge Spanning T ree window displays ST A parameters and allows you to alter parameters for the selected bridge as a whole, and for each individual bridging interface. The currently selected bridging interface is highligh[...]

Bridging 5-16 Bridge Spanning T ree Root Bridge Displays the MAC address of the bridge that is curr ently functioning as the Root Bridge. Root Cost Indicates the cost of the data path from this bridge to the Root Bridge. Each port on each bridge adds a “cost” to a particular path that a frame must travel. For example, if each port in a particul[...]

Bridge Spanning T ree 5-17 Bridging Hello Time This parameter indicates, in seconds, the length of time the Root Bridge (or bridge attempting to become the Root) waits before r esending Configuration BPDUs. The range for this field is 1 to 10 seconds, with a default value of 2 seconds. The Root Bridge sets the Hello T ime. Max Age This parameter [...]

Bridging 5-18 Bridge Spanning T ree P ath Cost Displays the cost that this port will contribute to the calculation of the overall Root path cost in a Configuration BPDU transmitted by this bridge port. Y ou can lower a port’s Path Cost to make the port more competitive in the selection of the Designated Port – for example, you may want to assi[...]

Bridge Spanning T ree 5-19 Bridging Changing Bridge Priority T o change the part of the bridge address that contains the identifier used in the Spanning T ree Algorithm for priority comparisons: 1. Highlight the Bridge Priority f ield. 2. Enter the new identifier , in he xadecimal f or mat; the allowed r ange is 0-FFFF he xadecimal. 3. Click on S[...]

Bridging 5-20 Bridge Spanning T ree Changing Max Age Time If the selected module is the Root Bridge or attempting to become the Root, and you want to change the maximum time that bridge protocol information will be kept before it is discar ded: 1. Highlight the Max Age field, and type in a new v alue. 2. Click on Set . The IEEE 802.1d specificati[...]

Filtering Database 5-21 Bridging Changing P ath Cost T o change the Path Cost: 1. If necessar y , select the desired por t b y clic king the mouse to highlight the por t in the low er r ight quadrant of the window . The low er left quadrant of the window will no w allow you to edit par ameters for the selected por t. 2. Highlight the P ath Cost fi[...]

Bridging 5-22 Filtering Database • Permanent entries are addr esses that you add to the Static Database (via the Filtering Database window) that are stor ed in the selected module’s battery-backed RAM. Since they remain in the module on shutdown or r estart, they are consider ed “Permanent.” • Static entries are addr esses that you add to[...]

Filtering Database 5-23 Bridging Figure 5-10. The Filtering Database W indow A scrollable Addr ess Entry panel allows you to: • V iew the address entries in the Filtering Database. • Alter an entry’s type (e.g., from Learned to Permanent, Dynamic, or Static). • V iew and configure the bridging action taking place on the packets entering ea[...]

Bridging 5-24 Filtering Database The following fields are listed in the top portion of the Filtering Database window: List The List checkboxes indicate whether the associated entry type (Permanent, Static, Dynamic, or Learned) will be displayed in the scrollable table of addr ess entries. A check next to the entry type indicates that it will be di[...]

Filtering Database 5-25 Bridging Receive P or t Indicates the number of the port on which a frame must be received in or der for the entry’s Port Filtering information to apply . An asterisk ( * ) indicates that the receive port is pr omiscuous, and applies to all ports of the bridge (assuming no conflicting entry applies). Y ou can change the r[...]

Bridging 5-26 Filtering Database Altering the Ageing Time T o alter the Ageing T ime for Dynamic and Learned entries: 1. Highlight the Ageing Time field with the cursor . 2. T ype in the new Ageing Time (allo wable r ange is 10 to 1,000,000 seconds). Changing the T ype of Entry Y ou can change any entry type from its curr ent type (Learned, Self, [...]

Filtering Database 5-27 Bridging 2. In the Filter Address field, type in the address (He x f or mat) for which y ou desire bridging. Be sure to add “-” as a separ ator between each byte in the address. 3. In the Receive P or t field, type in the por t at which the address must be detected f or br idging to take place . If you enter a v alue o[...]

Bridging 5-28 Filtering Database[...]

Inde x-1 Index A Absolute 4-10 ACT (active) 2-11 Address Mode 4-8 Ageing T ime (bridging) 5-22, 5-24 A TM 3-1 B BLK (Blocking) 2-10 Blocking 5-3, 5-5 Board Menus 2-7 Boot Prom, r evision 2-3 bridge port state 5-3 Bridge Priority 5-15 Bridge Protocol Data Units (BPDUs) 5-14 bridging interface status 5-2 BRK 2-10 Broken 5-3 buffer space 2-18, 5-12 C [...]

Inde x Inde x-2 H Hello T ime 5-17 Help button 1-4 Help Menu 2-7 Hold T ime 5-17 I I/F Summary interface performance statistics 2-15 I/F Summary window 2-14 Interface Group window 2-17 interface type (bridging) 5-3 IP addr ess 1-3, 2-3 Isolated 4-3 L L. Sta 2-15 Learned Database 5-21 Learned entries 5-22 Learning 5-3, 5-5 LER Estimate 2-11 LER Esti[...]

Inde x-3 Inde x Spanning T ree Algorithm 5-14 Static Database 5-21 Static entries 5-22 Station List 4-8 Switched V irtual Circuits (SVCs) 3-1 T technical support 1-5 T -Neg. 4-4 T opology 4-9 T opology Change 5-18 T race 4-3 T ransmit Frames 4-11 T ransmit Queue Size 2-19, 5-12 transparent bridges 5-21 T -Req. 4-4 twisted ring 4-6 U Unicast 2-18, 5[...]

Inde x Inde x-4[...]